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[MUSIC PLAYING]

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COLTON OGDEN: All right.

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Welcome back to GD50.

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This is Lecture 8.

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Today we're going to be
diving into the world of Unity

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for the first time,
which I'm excited about.

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Going to be a whirlwind tour, but
I'll try to cover as much as possible.

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Transitioning away from 2D and away
from Lua and LOVE 2D into 3D and C#

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in the context of Unity.

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Today we'll be talking
about Helicopter Game 3D.

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So Helicopter Game is a 2D game
that was really famous in the 2000s.

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It was a web game.

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I was sponsored on a bunch of websites.

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Addictinggames.com
still has it on there,

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and a few other websites have it.

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It was a flash game.

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But I remember playing it a lot.

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It was the old precursor
to Flappy Bird, which

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was mentioned on the Wikipedia page.

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There's a reference to it there.

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And this is what the
game play looked like.

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It was very similar to Flappy
Bird-- a little bit different

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in that, instead of trying to
avoid pipes, you're in a cave,

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and you're trying to avoid the
ceiling and the ground of the level.

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And there were these little obstacles
that would spawn in the middle,

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as well.

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So you'd have to navigate that.

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But it was the same exact mechanic--
the sort of like, click to go up.

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And then, when you didn't
click, your helicopter

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would just sink down via gravity.

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Today we'll be talking about a bunch
of brand new topics, things like Unity,

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first and foremost-- the ecosystem
with which we'll be doing

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a lot of the things we'll be doing.

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C# is the primary
language we'll be using.

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So we're going to take a step away
from dynamic languages and move towards

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statically-typed languages--

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languages like C#, and
Java, and the like.

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Blender is a program we'll
look at briefly today,

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just because, in the
context of 3D development,

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you're going to want to have a tool
that will let you create models.

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And so the 3D software that I like
to advocate for the most, especially

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for folks that are just starting
out, is Blender, because it's free,

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and open source, and it
has much the same feature

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set as any commercial software,
like 3D Studio Max, and Cinema 4D,

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and the like.

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We'll talk about what components
are-- entities and components, how

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they relate in this model that Unity
has adopted for all of its programming.

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Components are little pieces
of behavior that you can then

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combine to form a whole, that will then
drive the behavior of whatever object

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in your scene you want,
rather than having

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to customize its behavior via a long
chain of inheritance and instantiation.

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Colliders and triggers
are important in 3D--

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and 2D.

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But today we'll be
talking about colliders

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and triggers-- things
like the helicopter

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colliding with coins, and buildings,
and other planes that are flying.

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Each of those has to have a collider.

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And certain things have to be
considered triggers in order to trigger

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certain behavior with other entities.

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Prefabs and spawning-- prefabs
is a huge concept in Unity.

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So prefabs are basically
prefabricated objects

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that you can customize as you want
to-- lay them out in the editor,

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rather than having to
necessarily code all the details.

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And then you can instantiate
them in the actual scene,

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via code programmatically, in a way
that fits the model you're striving for.

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Texture scrolling is something
we'll look at briefly, because it's

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the way that we accomplish the infinite
scrolling aesthetic or behavior.

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And we'll look at how we can
do that in a different way

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than we've done before,
using u-v coordinates,

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and specifically looking
at materials, and modifying

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certain attributes of those materials.

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And lastly, to tie everything
together as we've done before,

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we'll look at audio-- things like
audio listeners and audio sources--

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what the difference is
between them, and how

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to add them easily to our game project.

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But first, a demo-- if
there would be anybody

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willing to come up and take a look
and play the 3D helicopter game that I

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put together, that would be awesome.

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Anybody?

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Steven?

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Awesome.

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Thank you so much.

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Let me go ahead and actually get it--

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so I've pre-built it.

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So let me go ahead and.

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So the nice thing about Unity is,
it exports to multiple platforms.

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And right out of the
gate, you can get just a--

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I didn't put an icon for it.

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But you can create just a
native application very easily.

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And so whenever you're
ready, go ahead and hit Play,

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and Up and Down will
move your helicopter.

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So this is the 3D helicopter game.

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And I don't think we have sound
live, but there should be audio.

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Oh, I might have actually-- here we go.

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[MUSIC PLAYING]

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There we go.

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That was my bad.

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So there is music playing.

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There's sound effects.

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So notice that we have a 3D model.

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This is what's called a 2.5D game.

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So even though everything is in 3D--

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the models and so forth--

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the actual axes upon which
we're bound are just two.

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We're just bound to, I
believe, the x and the y.

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Could be the z and the x.

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I don't recall offhand.

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But we're bound to just
simply two axes of movement.

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But all the models, as
we can see by the camera,

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are in 3D, including our helicopter.

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So we have a few things going on.

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We have skyscrapers
that are scrolling by.

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We have coins that are also going by
at the same speed as the skyscrapers.

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We have a background that
is infinitely scrolling.

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We have, of course, our helicopter
which has a rotating set of blades.

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And when we collide with a coin,
notice that we get a little--

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it might be hard to see in house,
but we have a little particle

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effect that plays.

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There's airplanes that
are flying up top,

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so we're instantiating those,
as well, to fly past us

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to provide another layer of obstacle.

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And if we collide with an airplane,
notice that we get de-spawned,

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and then we trigger another particle
effect to imitate an explosion.

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And then, notice we also have
a couple of other elements.

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We have a GUI.

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We have two GUI elements-- a
coin total at the top right,

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and then a game over here in
the middle of the screen, which

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only shows up once we have died.

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And the explosive behavior-- if you
want to collide with a building,

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you'll see that.

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It also triggers when you
collide with a building.

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So there's two things looking for these
explosions-- the airplanes up top,

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and the buildings below.

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Those are our two obstacles.

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But when they collide with the coins,
we should increment our coin total,

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and then display a
different particle effect.

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And then this goes on ad infinitum.

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You can press Space to restart.

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So we have keyboard input
that's based on what

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we press, different things happen.

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And so that's effectively the
demo that I've put together today.

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So thanks, Steven.

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I appreciate you coming up to demo it.

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So that's the 3D helicopter game.

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It's got most of the same mechanics
as the web version from before--

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I would say, maybe even more features
just to illustrate a few new concepts.

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But that's effectively what
we're going with today.

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We're just a pretty simple, Flappy
Bird esque differently-themed game,

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based on the same principles.

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Fly forever, avoid obstacles.

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And in this case, even
get little collectibles.

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And so notice that there are
also effectively two states

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in our game, which are just the playing
state, and then the game over state.

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The two are almost effectively the same.

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The only real difference is that one
doesn't have the helicopter present,

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and displays a different GUI
element in the middle of the screen.

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If you haven't downloaded Unity
already, there's two links here.

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So the top link is just
the catchall download link.

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And then the second
link is the beta link.

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So we're actually using
the beta in this course,

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because Unity has started
transitioning away

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from a numerical system
for their releases,

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and is now going yearly
with their releases.

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So the last long-term release
candidate was 2017's version.

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But now that we're almost
halfway through 2018,

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the newest beta is the 2018 version.

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It has a bunch of new features.

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So go ahead and check that out.

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And everything's been well
tested, and runs very well--

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very smoothly on Windows and Mac--

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with the new beta.

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So what is Unity?

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The difference between what we've done
so far and what we're doing today is,

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now we're actually using a
full-fledged game engine--

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this system.

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It's got a built in editor
and all this awesome, cool

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functionality that we really
didn't get with Love2D before.

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What we were doing before
was using a framework,

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and just implementing
everything purely in code.

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And as we'll see today, everything
that you want to do that's customizable

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effectively is--

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or can be-- done via code.

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But there are a lot of more
efficient and more user-friendly

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ways to accomplish the same
thing, which we'll take a look at.

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So Unity has a tremendous
market share right now.

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I forget.

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I think in 2016 it had like 43% of
all games released were done in Unity.

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I don't know what the
current numbers are.

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I couldn't find them.

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But there are other engines
that are also very well used--

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Unreal being among them.

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And Unreal actually may
have more market share now,

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because of games like
Fortnite, and because it's

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been improved a lot over the last couple
of years, and really marketed well.

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But Godot, CryEngine-- there
are a lot of game engines

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that are similar to
this that provide you

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this all-encompassing way of
dealing with your game scene

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and with all your game data.

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But Unity is a very easy engine
to start getting used to,

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and cranking things out,
and being productive with,

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without the tremendous
learning curve that some

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of the other engines
like Unreal might have.

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Unreal does have a more
user-friendly way of doing things.

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But if you want to get down into
the nitty gritty with Unreal,

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you're coding in semi-arcane C++.

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So for folks who aren't used to it and
aren't used to 3D game development,

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it can be kind of a
large board to get onto.

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The nice thing about
Unity, aside from the fact

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that it's fairly easy to get
started with, is that it's free.

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And you can use it completely
with all of its features

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until you start making over $100,000 in
gross revenue releasing Unity products.

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And then there are other tiers.

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The next tier above that is
if you start making $200,000,

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and you get new features
with these other tiers.

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But if you want to just
start up a new company,

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and use Unity, and take
something to market--

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completely free to do so.

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And once you get over $100,000,
that's a good problem to have.

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It's not necessarily
too much to ask to start

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paying Unity to use it
as a means of getting

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onto the market in the first place.

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And especially in mobile and VR,
Unity's sort of like the forefront.

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It's got even higher percentage.

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It's like 60-something or
70% market share on mobile.

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And then VR-- from the beginning,
it's marketed itself very strongly

00:10:05.774 --> 00:10:06.690
towards the use of VR.

00:10:06.690 --> 00:10:10.260
And we'll actually use
VR in the next lecture.

00:10:10.260 --> 00:10:14.850
And the way in which we will accomplish
all of the programmatic aspect

00:10:14.850 --> 00:10:17.160
of this-- getting things
actually implemented in code--

00:10:17.160 --> 00:10:20.400
is via C#, which is very different
than what we've used so far,

00:10:20.400 --> 00:10:23.010
which we've used Lua, which is
a dynamic scripting language,

00:10:23.010 --> 00:10:25.980
very much like JavaScript.

00:10:25.980 --> 00:10:30.270
So C# is very similar to Java, in
which things actually have types.

00:10:30.270 --> 00:10:34.674
And so here's a couple of screenshots
of what the Unity editor looks like.

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So the nice thing about the
Unity editor, actually--

00:10:36.840 --> 00:10:38.670
which we can see right
off the gate here--

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is that it's very customizable.

00:10:40.380 --> 00:10:43.050
So on the top, that's the default view.

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You have a bottom panel that
shows you all your resources,

00:10:46.340 --> 00:10:49.530
all your assets, things like
scripts, and shaders, and models,

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and textures, and sounds.

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You have a nice file browser there
on the left-hand side, which allows

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you to easily navigate your project.

00:10:55.350 --> 00:10:58.612
You don't have to go looking through
your Windows or Mac computer, using

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your finder, or whatnot,
or your File Explorer,

00:11:00.570 --> 00:11:02.278
and actually look
through all your files.

00:11:02.278 --> 00:11:05.310
You get a nice view there,
so that you stay integrated

00:11:05.310 --> 00:11:08.419
within the Unity ecosystem right there.

00:11:08.419 --> 00:11:11.460
On the right-hand side, you can see
all the behavior for whatever objects

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you might have in your scene.

00:11:12.690 --> 00:11:14.310
You get a nice big scene view.

00:11:14.310 --> 00:11:17.500
So rather than having to
run your game live, and look

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at the behavior that
way, you can actually

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see in advance what your
scene looks like, and analyze

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your game objects that
way, and their appearances,

00:11:25.220 --> 00:11:27.080
and whatever you want to do with them.

00:11:27.080 --> 00:11:29.000
And lay them out
perfectly, rather than have

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to programmatically figure things out.

00:11:31.607 --> 00:11:33.440
And on the left-hand
side there, you can see

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a full list of all the game objects.

00:11:35.052 --> 00:11:36.760
And then on the bottom
right screen shot,

00:11:36.760 --> 00:11:39.550
you can see that the editor
is heavily customizable.

00:11:39.550 --> 00:11:41.300
So you can lay things
out however you want

00:11:41.300 --> 00:11:43.310
to to fit your style of development.

00:11:43.310 --> 00:11:47.737
I often like to have a panel on
top, which shows me my scene view,

00:11:47.737 --> 00:11:50.570
but then have a panel right below
that, that shows me the game view.

00:11:50.570 --> 00:11:54.470
So if I'm actually running a
game and seeing it happen live,

00:11:54.470 --> 00:11:58.310
I can also see it in the scene,
and rotate around in this god mode

00:11:58.310 --> 00:12:00.380
that you can get in a lot of games.

00:12:00.380 --> 00:12:03.700
And actually analyze
and see things that way,

00:12:03.700 --> 00:12:05.800
and analyze their
behavior frame by frame,

00:12:05.800 --> 00:12:08.930
even if I want to, in a way
that's not possible with however

00:12:08.930 --> 00:12:13.010
I might have coded the camera
in the actual game itself.

00:12:13.010 --> 00:12:14.810
So C#.

00:12:14.810 --> 00:12:17.334
So has anybody in here
used a static language,

00:12:17.334 --> 00:12:19.250
or is familiar with
statically-typed languages

00:12:19.250 --> 00:12:21.360
versus dynamically-typed languages?

00:12:21.360 --> 00:12:23.270
[INAUDIBLE], Steven.

00:12:23.270 --> 00:12:27.610
So what languages have you guys
used, just out of curiosity?

00:12:27.610 --> 00:12:28.110
Steven.

00:12:28.110 --> 00:12:29.320
STEVEN: Java, C, C++.

00:12:29.320 --> 00:12:30.445
COLTON OGDEN: Java, C, C++.

00:12:30.445 --> 00:12:31.165
Donny?

00:12:31.165 --> 00:12:31.690
DONNY: [INAUDIBLE]

00:12:31.690 --> 00:12:32.320
COLTON OGDEN: C and C++.

00:12:32.320 --> 00:12:32.820
OK.

00:12:32.820 --> 00:12:35.940
So to you guys, this
will be pretty similar.

00:12:35.940 --> 00:12:38.516
So C# is very similar to Java.

00:12:38.516 --> 00:12:40.140
Almost looks identical at first glance.

00:12:40.140 --> 00:12:42.830
There are some features
that are different.

00:12:42.830 --> 00:12:49.100
But it was Microsoft's
initiative to compete with Java.

00:12:49.100 --> 00:12:51.200
It's a Microsoft language,
first and foremost.

00:12:51.200 --> 00:12:55.805
But there are ways to run
C# code on other platforms,

00:12:55.805 --> 00:12:57.680
primarily with the use
of what's called Mono.

00:12:57.680 --> 00:13:01.760
So Mono is an open source implementation
of what's called the CLR--

00:13:01.760 --> 00:13:03.740
the common language runtime--

00:13:03.740 --> 00:13:09.980
which is how Microsoft allows several
of its languages, like F#, and C#,

00:13:09.980 --> 00:13:12.320
and Visual C++, Visual Basic.

00:13:12.320 --> 00:13:15.080
They all compile to this
intermediary format,

00:13:15.080 --> 00:13:17.450
like how Java compiles to bytecode.

00:13:17.450 --> 00:13:21.520
And you can run any of
those languages' code--

00:13:21.520 --> 00:13:24.880
their version of the
bytecode-- with the CLR.

00:13:24.880 --> 00:13:27.440
Mono-- what Mono is,
and what Unity relies on

00:13:27.440 --> 00:13:30.830
to allow its use across
multiple operating systems,

00:13:30.830 --> 00:13:33.950
is a CLR that's not
just Windows specific.

00:13:33.950 --> 00:13:37.380
It actually runs on Mac and
on Linux machines, as well.

00:13:37.380 --> 00:13:43.580
And you'll actually see evidence of
its existence via the nomenclature used

00:13:43.580 --> 00:13:45.229
for Mono behavior.

00:13:45.229 --> 00:13:47.270
So within Unity, there's
this thing called a Mono

00:13:47.270 --> 00:13:49.230
behavior, which we'll take a look at.

00:13:49.230 --> 00:13:53.360
From the beginning, actually, Unity
was developed for Mac platforms

00:13:53.360 --> 00:13:54.920
exclusively.

00:13:54.920 --> 00:14:00.020
But in 2012 or 2011 they ended up making
it usable across all major desktop

00:14:00.020 --> 00:14:02.150
operating systems.

00:14:02.150 --> 00:14:04.760
But C#-- suffice to
say, very similar Java.

00:14:04.760 --> 00:14:05.850
We'll look at its syntax.

00:14:05.850 --> 00:14:09.770
But it's different from Lua in
that, with Lua, you could just say,

00:14:09.770 --> 00:14:14.150
oh, x equals 10, or object
equals-- and then create

00:14:14.150 --> 00:14:16.220
a table with whatever you want.

00:14:16.220 --> 00:14:20.015
C# is a lot less flexible in this sense,
in that you have to actually tell it

00:14:20.015 --> 00:14:23.460
in advance what each data type
is that you're trying to make.

00:14:23.460 --> 00:14:26.720
So you can't just create
a table or a integer.

00:14:26.720 --> 00:14:31.820
You actually have to say, int
my_int, or x equals, and then 10,

00:14:31.820 --> 00:14:33.020
and then semi-colon.

00:14:33.020 --> 00:14:37.430
So there's also more
syntax to be conscious of.

00:14:37.430 --> 00:14:41.150
And so really quickly, I can show
you just what some C# looks like.

00:14:41.150 --> 00:14:43.590
We'll take a look at
this again going forward.

00:14:43.590 --> 00:14:46.620
But as you can see here, we have public.

00:14:46.620 --> 00:14:49.160
So that's another thing about C#.

00:14:49.160 --> 00:14:51.740
In Java, if you're
familiar with Java, they're

00:14:51.740 --> 00:14:54.270
object-oriented programming languages.

00:14:54.270 --> 00:14:59.000
And as such, there are objects
that are public and private,

00:14:59.000 --> 00:15:04.130
and you have access specifiers for
different variables and classes

00:15:04.130 --> 00:15:06.590
that will tell other variables
and classes whether or not

00:15:06.590 --> 00:15:08.270
they can communicate effectively.

00:15:08.270 --> 00:15:12.230
So public class just means effectively
anybody can see this class.

00:15:12.230 --> 00:15:15.590
Other classes can see this.

00:15:15.590 --> 00:15:17.880
But then you have--

00:15:17.880 --> 00:15:21.204
see if I have one of these
that has a private variable.

00:15:21.204 --> 00:15:22.370
I know there's at least one.

00:15:22.370 --> 00:15:23.120
Here we go.

00:15:23.120 --> 00:15:25.220
So private, Text, text
here, for example.

00:15:25.220 --> 00:15:27.980
So first of all, notice that
these are variable declarations

00:15:27.980 --> 00:15:29.960
like we've seen before.

00:15:29.960 --> 00:15:32.450
We're saying, this is a
variable that I'm going to use.

00:15:32.450 --> 00:15:34.940
In this case, public
GameObject helicopter.

00:15:34.940 --> 00:15:36.470
So I'm just defining it.

00:15:36.470 --> 00:15:37.880
Or I'm declaring it.

00:15:37.880 --> 00:15:38.920
I'm not defining it.

00:15:38.920 --> 00:15:40.220
It doesn't equal anything yet.

00:15:40.220 --> 00:15:43.730
But I'm saying, this is
going to exist, right?

00:15:43.730 --> 00:15:50.510
You can say equals something, and
then define it on the same line.

00:15:50.510 --> 00:15:55.730
But in this case, we are just declaring
in advance what different variables

00:15:55.730 --> 00:15:57.742
we're going to need later on.

00:15:57.742 --> 00:15:58.700
Like for example, here.

00:15:58.700 --> 00:16:00.134
We see, in our start method.

00:16:00.134 --> 00:16:03.050
And we'll go over what all these
methods are and how they're relevant.

00:16:03.050 --> 00:16:05.690
But we can see here, text equals--

00:16:05.690 --> 00:16:08.880
and then we're calling some
function called GetComponent.

00:16:08.880 --> 00:16:10.760
And then we have some
funky syntax here--

00:16:10.760 --> 00:16:12.800
less than, Text, greater than--

00:16:12.800 --> 00:16:15.500
and then function call syntax--

00:16:15.500 --> 00:16:16.740
two parentheses.

00:16:16.740 --> 00:16:19.880
So we can see that
there's a lot more syntax.

00:16:19.880 --> 00:16:22.070
But all of the same
principles still hold true.

00:16:22.070 --> 00:16:25.330
It's still much the same way
to think about programming.

00:16:25.330 --> 00:16:28.250
It's just, there's a little
bit more to stay conscious of.

00:16:28.250 --> 00:16:32.490
And we trade off this
dynamism for more performance.

00:16:32.490 --> 00:16:35.870
So that's ultimately what it comes down
to-- static versus dynamic languages,

00:16:35.870 --> 00:16:39.930
you're trading flexibility
for performance, in this case.

00:16:39.930 --> 00:16:42.320
Though C# obviously is
a lot faster than Lua.

00:16:42.320 --> 00:16:44.250
We can do a lot more with it.

00:16:44.250 --> 00:16:47.280
And actually, Unity isn't
itself programmed in C#.

00:16:47.280 --> 00:16:50.390
Unity itself is programmed in C++.

00:16:50.390 --> 00:16:58.320
But it allows us to program any
behavior that we want to with C#.

00:16:58.320 --> 00:16:58.820
All right.

00:16:58.820 --> 00:17:04.760
So that's a look at C# so we can see
also what I was alluding to up here.

00:17:04.760 --> 00:17:08.400
We have our private, public,
and we do things with them.

00:17:08.400 --> 00:17:12.290
And then, depending on what
we've declared public or private,

00:17:12.290 --> 00:17:14.089
these things also
transfer into the editor.

00:17:14.089 --> 00:17:16.649
We'll see how all of
that comes together soon.

00:17:16.649 --> 00:17:19.190
But suffice to say, that's a
look at C#-- what it looks like.

00:17:19.190 --> 00:17:21.356
And we'll use it, and we'll
get comfortable with it.

00:17:21.356 --> 00:17:25.940
But it's a little bit different
than what we've done thus far.

00:17:25.940 --> 00:17:29.450
Away from programming, we'll a
very brief look at what Blender is.

00:17:29.450 --> 00:17:31.820
So I have it installed here.

00:17:31.820 --> 00:17:33.800
And this isn't required for the course.

00:17:33.800 --> 00:17:36.410
I will provide you with all
the models and all the assets

00:17:36.410 --> 00:17:39.320
that you need to get working.

00:17:39.320 --> 00:17:40.730
But this is what Blender is.

00:17:40.730 --> 00:17:46.790
So Blender almost looks, at first
glance, very similar to Unity.

00:17:46.790 --> 00:17:50.300
The big difference is, this
is meant to create new assets.

00:17:50.300 --> 00:17:53.540
And technically, Blender does
have a built-in game engine,

00:17:53.540 --> 00:17:55.850
but it's not used for
that purpose very much.

00:17:55.850 --> 00:18:00.257
But the sole purpose that we
would be using it in this course

00:18:00.257 --> 00:18:01.840
would be just to create new 3D models.

00:18:01.840 --> 00:18:06.500
So as you can see here, I can click on
these vertices, and move them around.

00:18:06.500 --> 00:18:12.050
And I'm not a guru by any stretch of the
imagination when it comes to Blender.

00:18:12.050 --> 00:18:15.230
But the helicopter, and
jet, and skyscrapers,

00:18:15.230 --> 00:18:18.200
and those kind of simple models,
I made all of those in Blender.

00:18:18.200 --> 00:18:21.229
And those are bundled
with the project, if you

00:18:21.229 --> 00:18:23.270
want to take a look at
how those are implemented.

00:18:23.270 --> 00:18:25.750
And you can download Blender at the--

00:18:25.750 --> 00:18:27.500
I forget what the exact
link is, actually.

00:18:27.500 --> 00:18:28.740
Let's take a look.

00:18:28.740 --> 00:18:30.610
Blender dot org.

00:18:33.780 --> 00:18:36.120
And then, if we just go
down here, download Blender,

00:18:36.120 --> 00:18:39.720
2.79 looks like the most recent version.

00:18:39.720 --> 00:18:42.000
Blender 2.8-- I guess
it's in development.

00:18:42.000 --> 00:18:45.220
But there's nothing concrete
about that on the front page.

00:18:45.220 --> 00:18:45.720
But yeah.

00:18:45.720 --> 00:18:48.660
If you want to model 3D
assets, and you're curious,

00:18:48.660 --> 00:18:51.240
and you want a free piece
of really awesome software,

00:18:51.240 --> 00:18:53.040
can't recommend Blender enough.

00:18:53.040 --> 00:18:57.300
But like I said, I'm going to spend
too much time on it, because it's not

00:18:57.300 --> 00:18:59.640
something that will actually
be required in the course

00:18:59.640 --> 00:19:02.000
to implement 3D models,
to create 3D models,

00:19:02.000 --> 00:19:07.040
since I'll be providing all of that to
you in the project in the GitHub repo.

00:19:07.040 --> 00:19:10.450
And so here is a screenshot
of basically what we just saw.

00:19:10.450 --> 00:19:13.740
So the fundamental part of Unity.

00:19:13.740 --> 00:19:17.550
So first of all, let's take
a look at the Unity editor.

00:19:17.550 --> 00:19:20.820
So we can see here much of
what we saw in the screenshots.

00:19:20.820 --> 00:19:24.030
But here, I am live
looking at my scene, right?

00:19:24.030 --> 00:19:25.380
I have a helicopter.

00:19:25.380 --> 00:19:27.780
I have this background back here.

00:19:27.780 --> 00:19:28.650
I have a camera--

00:19:28.650 --> 00:19:30.060
that's right here.

00:19:30.060 --> 00:19:32.180
You can see that it's a camera, because
it's got the little camera icon.

00:19:32.180 --> 00:19:34.500
But it's effectively just
an invisible game object.

00:19:34.500 --> 00:19:38.670
It's not actually going to be
rendered to the screen ever.

00:19:38.670 --> 00:19:42.204
And notice that there are no
skyscrapers, no coins, no jets,

00:19:42.204 --> 00:19:43.120
or anything like that.

00:19:43.120 --> 00:19:45.090
Those are all instantiated dynamically.

00:19:45.090 --> 00:19:47.135
But this is the beginning of our scene.

00:19:47.135 --> 00:19:48.510
And it's all laid out in advance.

00:19:48.510 --> 00:19:50.426
And we can see here with
this camera preview--

00:19:50.426 --> 00:19:53.190
which is kind of hard to see
because it's really small--

00:19:53.190 --> 00:19:56.550
but here's a larger view
of what it looks like.

00:19:56.550 --> 00:19:59.192
And then we've got a GUI element
here, we've got coins here.

00:19:59.192 --> 00:20:00.150
We have our helicopter.

00:20:00.150 --> 00:20:04.950
But all of this is a marked
difference from what we've gotten

00:20:04.950 --> 00:20:07.700
used to, which is, program
everything, and sort of load it,

00:20:07.700 --> 00:20:09.660
and, oh, did I put this
in the right position?

00:20:09.660 --> 00:20:09.780
No.

00:20:09.780 --> 00:20:10.280
I didn't.

00:20:10.280 --> 00:20:10.920
So I got to.

00:20:10.920 --> 00:20:13.720
If I wanted to come
over here and just move

00:20:13.720 --> 00:20:15.840
the helicopter a little bit which--

00:20:15.840 --> 00:20:16.540
like that.

00:20:16.540 --> 00:20:17.040
Whoops.

00:20:17.040 --> 00:20:17.873
I just triggered it.

00:20:17.873 --> 00:20:20.670
If you click on
something, by the way, it

00:20:20.670 --> 00:20:23.532
will play any particle systems
that are associated with it.

00:20:23.532 --> 00:20:25.740
So you can actually get a
preview for those, as well.

00:20:25.740 --> 00:20:27.840
But I can easily just move
it here, to the right,

00:20:27.840 --> 00:20:30.600
or to the left, before
the game actually starts.

00:20:30.600 --> 00:20:33.760
And if I click on the
camera, we can see it there.

00:20:33.760 --> 00:20:37.780
It's a little bit shifted to the left,
as opposed to what it was before.

00:20:37.780 --> 00:20:41.560
But if I just press Command-Z couple
of times, take it back to normal.

00:20:41.560 --> 00:20:44.500
So game object is an important concept.

00:20:44.500 --> 00:20:49.500
So a game object is basically
everything in Unity.

00:20:49.500 --> 00:20:51.840
So the camera is a game object.

00:20:51.840 --> 00:20:54.090
The helicopter, which is
right here, is a game object.

00:20:54.090 --> 00:20:57.180
Everything, by the way, that you
want to see in your scene in Unity

00:20:57.180 --> 00:20:59.760
is on this left-hand
hierarchy right here.

00:20:59.760 --> 00:21:02.760
So helicopter, the game object.

00:21:02.760 --> 00:21:05.220
There's got to be a light
source in a 3D scene in order

00:21:05.220 --> 00:21:06.720
for you to actually see things.

00:21:06.720 --> 00:21:09.330
So directional light--
that's a game object.

00:21:09.330 --> 00:21:12.360
Background skyscraper spawner--
we don't see it anywhere.

00:21:12.360 --> 00:21:13.650
But that's also a game object.

00:21:13.650 --> 00:21:15.960
It's just an invisible one.

00:21:15.960 --> 00:21:17.010
A coin spawner.

00:21:17.010 --> 00:21:20.550
There's something called a canvas,
which if we double-click that,

00:21:20.550 --> 00:21:26.670
we can see we have this obscenely
large GUI here that, paradoxically,

00:21:26.670 --> 00:21:29.850
isn't on top of our scene.

00:21:29.850 --> 00:21:33.210
Unity does a very interesting
thing with all of its GUI elements,

00:21:33.210 --> 00:21:40.080
in that it basically maps
the canvas to one pixel

00:21:40.080 --> 00:21:44.460
being equal to one Unity unit, which
is usually equivalent to a meter.

00:21:44.460 --> 00:21:48.720
And it draws this in a
different draw call than it

00:21:48.720 --> 00:21:52.710
draws all of the actual 3D stuff--

00:21:52.710 --> 00:21:55.710
all the stuff that's down here,
basically-- in World Space.

00:21:55.710 --> 00:21:59.760
So when you create a canvas
and you see it's gigantic,

00:21:59.760 --> 00:22:01.330
that's just Unity's way of doing GUI.

00:22:01.330 --> 00:22:03.180
It's strange.

00:22:03.180 --> 00:22:05.490
But apparently they do it
for performance reasons,

00:22:05.490 --> 00:22:08.700
because they don't have to calculate
like fractional points of where

00:22:08.700 --> 00:22:13.530
the UI is supposed to be in World
Space, which can get really small.

00:22:13.530 --> 00:22:18.100
But the canvas is a game object.

00:22:18.100 --> 00:22:21.309
Notice that helicopter has children.

00:22:21.309 --> 00:22:24.350
It's got blades, a body, and then a
blades collider, which actually could

00:22:24.350 --> 00:22:26.390
have been part of the blades object.

00:22:26.390 --> 00:22:30.420
Canvas itself has two children--
coin text and game over.

00:22:30.420 --> 00:22:34.590
And those are the text on the top
right, and "game over" in the center.

00:22:34.590 --> 00:22:38.430
So those are just two
text objects, which

00:22:38.430 --> 00:22:43.200
are labels, that we can just populate
with whatever text data we want.

00:22:43.200 --> 00:22:45.210
The event system is an object.

00:22:45.210 --> 00:22:49.110
That just gets added to your scene
automatically when you add a canvas.

00:22:49.110 --> 00:22:52.590
Airplane spawner, explosion
particles, and explosion sound.

00:22:52.590 --> 00:22:54.780
So we have all these different objects.

00:22:54.780 --> 00:22:58.359
They're all part of our scene,
and they all do different things.

00:22:58.359 --> 00:23:00.150
But at the core, they're
just game objects.

00:23:00.150 --> 00:23:03.600
That's the core-- like the bottom type.

00:23:03.600 --> 00:23:04.382
Yes?

00:23:04.382 --> 00:23:07.274
AUDIENCE: So I would imagine
you're not actually using

00:23:07.274 --> 00:23:11.130
a helicopter [INAUDIBLE].

00:23:11.130 --> 00:23:12.972
COLTON OGDEN: Correct.

00:23:12.972 --> 00:23:16.924
AUDIENCE: So should you
actually reset the position

00:23:16.924 --> 00:23:20.890
of the background [INAUDIBLE]?

00:23:20.890 --> 00:23:25.420
COLTON OGDEN: So the question
was, since we are maintaining

00:23:25.420 --> 00:23:28.255
a consistent position with the--

00:23:28.255 --> 00:23:30.720
I'm going to try and
scroll in, there we go.

00:23:30.720 --> 00:23:32.726
The nice about Unity 2
is, if you right click,

00:23:32.726 --> 00:23:34.600
you can use W-A-S-D to
move around the scene,

00:23:34.600 --> 00:23:37.420
which is super easy and convenient.

00:23:37.420 --> 00:23:40.570
But the helicopter
here stays in one spot.

00:23:40.570 --> 00:23:43.630
And the camera always
stays in one spot forever.

00:23:43.630 --> 00:23:50.890
So do we move the
background image, like we

00:23:50.890 --> 00:23:54.070
do in our Love2D
implementation of Flappy Bird,

00:23:54.070 --> 00:23:55.930
where we reset its position?

00:23:55.930 --> 00:23:57.610
And the answer is--

00:23:57.610 --> 00:24:03.170
I will play it right now in scene
view, and let you decide for yourself.

00:24:03.170 --> 00:24:04.940
So let's go to Window.

00:24:04.940 --> 00:24:06.322
I'm gonna go to Layouts.

00:24:06.322 --> 00:24:08.280
So I like the two by
three, like I said before,

00:24:08.280 --> 00:24:14.080
so you can see the scene and the
game running live at the same time.

00:24:14.080 --> 00:24:16.870
I'm going to move my camera
in the scene so that I'm

00:24:16.870 --> 00:24:21.680
looking at this from back here.

00:24:21.680 --> 00:24:26.460
And then I'm going to play the game.

00:24:26.460 --> 00:24:29.750
[MUSIC PLAYING]

00:24:29.750 --> 00:24:32.770
But so.

00:24:32.770 --> 00:24:37.090
Here's where we-- I'm just
going to hold it still.

00:24:37.090 --> 00:24:40.570
So what do we think is happening?

00:24:40.570 --> 00:24:42.280
Does it look like our thing is moving?

00:24:42.280 --> 00:24:43.238
Or is it staying still?

00:24:46.720 --> 00:24:48.910
It is staying still.

00:24:48.910 --> 00:24:52.940
Any guesses as to how
we're achieving this?

00:24:52.940 --> 00:24:54.670
Changing the texture.

00:24:54.670 --> 00:24:58.120
We are scrolling its texture.

00:24:58.120 --> 00:25:01.540
So when you take a texture
and apply it to a 3D surface,

00:25:01.540 --> 00:25:08.880
you map the texture coordinates to
the 3D coordinates of the object

00:25:08.880 --> 00:25:09.880
that you want to render.

00:25:09.880 --> 00:25:11.134
It's called UV Mapping.

00:25:11.134 --> 00:25:14.050
They call it UV, because usually,
when you're dealing with 3D objects,

00:25:14.050 --> 00:25:15.340
you have your x, y, z.

00:25:15.340 --> 00:25:18.670
And then you want to think of your
texture separately from the 3D objects.

00:25:18.670 --> 00:25:21.520
So you use u, v instead of x, y,
since you already have x, y, z

00:25:21.520 --> 00:25:22.810
allocated for your 3D object.

00:25:27.840 --> 00:25:32.500
Basically, there's an
offset part of the texture--

00:25:32.500 --> 00:25:34.340
the material that holds the texture--

00:25:34.340 --> 00:25:39.040
there's an offset field that
will reposition the UV mapping

00:25:39.040 --> 00:25:43.160
of that texture onto the 3D surface.

00:25:43.160 --> 00:25:47.680
And when you offset it, it will
just sort of wrap itself around,

00:25:47.680 --> 00:25:49.070
if that makes any sense.

00:25:49.070 --> 00:25:51.054
So what we do is we--

00:25:51.054 --> 00:25:53.540
and I can actually show you
in the code where this is.

00:25:53.540 --> 00:25:55.990
This is going to be mentioned
at the end of the lecture.

00:25:55.990 --> 00:26:01.300
But we have the scrolling
background component here.

00:26:01.300 --> 00:26:06.070
And there's this thing on each
material called a texture offset,

00:26:06.070 --> 00:26:10.240
which basically shifts the UV mapping
of your texture to your 3D object.

00:26:10.240 --> 00:26:14.740
And so, by setting that texture
offset to some value offset,

00:26:14.740 --> 00:26:17.740
which is very similar to
what we've done before.

00:26:17.740 --> 00:26:21.370
Notice that offset is just
scroll speed times time--

00:26:21.370 --> 00:26:23.424
Time.time, in this case.

00:26:23.424 --> 00:26:26.340
And I don't mean to overwhelm with,
necessarily, all the details here.

00:26:26.340 --> 00:26:29.980
But the bigger picture is
that we're taking time--

00:26:29.980 --> 00:26:33.430
the amount of time since the
beginning of the game is started--

00:26:33.430 --> 00:26:36.460
and we have some scroll speed
that we've pre-determined.

00:26:36.460 --> 00:26:40.180
And we can just scroll
the texture offset here.

00:26:40.180 --> 00:26:41.770
We're just placing it here at the x.

00:26:41.770 --> 00:26:44.290
So this new Vector2, offset 0--

00:26:44.290 --> 00:26:46.320
just think of these two as an x and y--

00:26:46.320 --> 00:26:47.830
a vector 2, vector 3.

00:26:47.830 --> 00:26:50.060
Vectors are just
combinations of numbers.

00:26:50.060 --> 00:26:52.720
So 1, 2, 3, 4-- however many you want.

00:26:52.720 --> 00:26:55.240
A Vector 2 offset in 0.

00:26:55.240 --> 00:26:57.370
So we don't want to
scroll on the y-axis.

00:26:57.370 --> 00:26:59.020
We just want to scroll left to right.

00:26:59.020 --> 00:27:03.100
So we're going to apply no
texture offset to our y-axis,

00:27:03.100 --> 00:27:06.700
but we want to apply a
texture offset to our x-axis.

00:27:06.700 --> 00:27:09.220
So that's what their offset there is.

00:27:09.220 --> 00:27:11.140
And I included it also here--

00:27:11.140 --> 00:27:13.960
notice there's a Bump
Map texture offset.

00:27:13.960 --> 00:27:16.050
There's no Bump Map
actually on our texture.

00:27:16.050 --> 00:27:17.650
So a Bump Map is effectively--

00:27:17.650 --> 00:27:21.730
I can maybe find a good
Google image for it,

00:27:21.730 --> 00:27:23.360
if you're not familiar with a Bump Map.

00:27:25.915 --> 00:27:26.665
Let me go in here.

00:27:30.050 --> 00:27:35.240
I'm going to hope that there's no shady
images on Google Images, but a Bump

00:27:35.240 --> 00:27:37.010
Map--

00:27:37.010 --> 00:27:37.710
can we see it?

00:27:37.710 --> 00:27:41.110
Well, it's kind of hard to tell.

00:27:41.110 --> 00:27:46.640
But in a lot of 3D games, you'll
see like bumpiness and shininess

00:27:46.640 --> 00:27:47.960
on surfaces.

00:27:47.960 --> 00:27:51.050
And that's accomplished the majority
of the time using Bump Mapping.

00:27:51.050 --> 00:27:55.010
Because obviously, if you were to model
every single tiny little bump or model

00:27:55.010 --> 00:27:59.390
in a surface, it would get extremely
difficult to render large objects.

00:27:59.390 --> 00:28:02.990
Because you're looking at
thousands of polygons for a surface

00:28:02.990 --> 00:28:06.440
that was actually this
detailed in a game.

00:28:06.440 --> 00:28:09.290
So what you do is, you take
what's called a Bump Map,

00:28:09.290 --> 00:28:11.570
and the Bump Map gets--

00:28:11.570 --> 00:28:18.350
during lighting, it will effectively
skew the surface normals of a 3D mesh.

00:28:18.350 --> 00:28:23.840
So effectively, it will pretend as if
your 3D mesh has a bunch of bumps in it

00:28:23.840 --> 00:28:26.390
for the lighting.

00:28:26.390 --> 00:28:27.350
Only for the lighting.

00:28:27.350 --> 00:28:32.540
And so when it gets lit, and it gets
shaded, it looks as if it's bumpy,

00:28:32.540 --> 00:28:35.030
but you're still dealing with
a completely flat, completely

00:28:35.030 --> 00:28:39.650
simple cubic mesh in this case,
or whatever mesh you want.

00:28:39.650 --> 00:28:43.027
And so the long story
short, here, if you

00:28:43.027 --> 00:28:45.860
wanted to include a Bump Map on
whatever surface you want to scroll,

00:28:45.860 --> 00:28:47.720
or if you want to edit
the Bump Map, this

00:28:47.720 --> 00:28:52.110
is here just because you can also
manipulate the Bump Map texture offset.

00:28:52.110 --> 00:28:58.130
It's an included field in a material.

00:28:58.130 --> 00:29:02.770
So any questions as to
how this works at large?

00:29:02.770 --> 00:29:06.230
We still have a lot to cover before
we go into a lot of the specifics.

00:29:06.230 --> 00:29:11.310
But conceptually, do we
understand how this sort of works?

00:29:11.310 --> 00:29:12.480
OK?

00:29:12.480 --> 00:29:12.980
Cool.

00:29:12.980 --> 00:29:14.271
So let's go back to the slides.

00:29:18.390 --> 00:29:18.890
Right.

00:29:18.890 --> 00:29:20.473
So we were talking about game objects.

00:29:20.473 --> 00:29:25.890
So all of those things that we
saw before were just game objects.

00:29:25.890 --> 00:29:32.120
So let's go back to the default layout,
and then we can look back at our scene.

00:29:32.120 --> 00:29:33.380
So this is our scene.

00:29:33.380 --> 00:29:36.120
All of those things were
all of our game objects.

00:29:36.120 --> 00:29:38.300
Those are ultimately containers.

00:29:38.300 --> 00:29:39.990
I talked about this in a prior lecture.

00:29:39.990 --> 00:29:43.820
But this is the beginning of an entity
component system, in which case,

00:29:43.820 --> 00:29:45.600
these game objects are our entities.

00:29:45.600 --> 00:29:47.510
They are the entity class--

00:29:47.510 --> 00:29:50.240
container class-- for
what drives behavior.

00:29:50.240 --> 00:29:55.610
And the thing that allows us to
actually get interesting behavior out

00:29:55.610 --> 00:29:59.400
of this sort of abstraction
is the use of components.

00:29:59.400 --> 00:30:01.130
And we'll talk about that.

00:30:01.130 --> 00:30:05.150
So components are all of the
things on the right-hand side,

00:30:05.150 --> 00:30:07.740
by default of the Unity editor.

00:30:07.740 --> 00:30:09.894
So if we're looking at
our camera, for example,

00:30:09.894 --> 00:30:12.060
and we take a look at all
these things on the right,

00:30:12.060 --> 00:30:14.660
we can see that we have
something called a transform,

00:30:14.660 --> 00:30:16.550
we have something called a camera.

00:30:16.550 --> 00:30:19.060
A GUI layer deprecated,
so that's by default.

00:30:19.060 --> 00:30:21.750
It was imported from a
prior version of Unity,

00:30:21.750 --> 00:30:23.635
so you could actually delete this.

00:30:23.635 --> 00:30:26.110
A flare layer, which we're not using.

00:30:26.110 --> 00:30:29.210
An audio listener-- I believe that
comes with all cameras by default,

00:30:29.210 --> 00:30:30.910
though, in case you do want to use it.

00:30:30.910 --> 00:30:33.410
An audio listener and an audio source.

00:30:33.410 --> 00:30:37.120
So all of these different
pieces are components.

00:30:37.120 --> 00:30:40.670
They are what drive the
behavior of this game object.

00:30:40.670 --> 00:30:43.840
We can create just a brand
new, empty game object-- oops,

00:30:43.840 --> 00:30:45.380
I created it as a child.

00:30:45.380 --> 00:30:48.720
We can create a brand new,
empty game object here.

00:30:48.720 --> 00:30:51.380
It's just a game object in our scene.

00:30:51.380 --> 00:30:55.430
And it's right where our mouse is.

00:30:55.430 --> 00:30:56.810
Well, it's right here.

00:30:56.810 --> 00:30:59.100
And it does nothing.

00:30:59.100 --> 00:31:01.130
It has one component.

00:31:01.130 --> 00:31:03.704
And that component is the transform.

00:31:03.704 --> 00:31:05.120
Anybody guess what a transform is?

00:31:08.850 --> 00:31:09.350
Yeah.

00:31:09.350 --> 00:31:11.810
AUDIENCE: Is that position,
rotation, scale, et cetera?

00:31:11.810 --> 00:31:12.560
COLTON OGDEN: Yes.

00:31:12.560 --> 00:31:16.580
It is the position, rotation,
and scale of a game object.

00:31:16.580 --> 00:31:20.120
Something that was before
put into six fields--

00:31:20.120 --> 00:31:22.940
or in this case, nine
fields, potentially, or maybe

00:31:22.940 --> 00:31:29.570
three fields with children, is now
an object that we can modify at will.

00:31:29.570 --> 00:31:32.960
Well, it's a component
that we can modify at will.

00:31:32.960 --> 00:31:36.380
So if I do this-- notice,
I'm just scrolling the x.

00:31:36.380 --> 00:31:40.520
It's just moving that transform, which
is just the position of that object.

00:31:40.520 --> 00:31:44.150
And Unity knows to look at
the transform component,

00:31:44.150 --> 00:31:47.720
and render our object based
upon where its transform lies,

00:31:47.720 --> 00:31:51.320
rather than us having to manually
set all these things, which we still

00:31:51.320 --> 00:31:52.760
can do in the code.

00:31:52.760 --> 00:31:55.460
We can just modify them
in the Unity editor

00:31:55.460 --> 00:31:57.500
directly via a graphical interface.

00:31:57.500 --> 00:32:01.260
It's just an interesting,
helpful layer of abstraction.

00:32:01.260 --> 00:32:05.344
So a transform is a component--
a camera, in this case.

00:32:05.344 --> 00:32:06.260
It's just a component.

00:32:06.260 --> 00:32:09.900
We can attach this to anything we
want to, and it becomes a camera.

00:32:09.900 --> 00:32:13.340
And then we can set it to be
either the default camera or not.

00:32:13.340 --> 00:32:15.550
The camera has a bunch
of different things.

00:32:15.550 --> 00:32:18.710
And I can't claim to know all
of the fields of every object

00:32:18.710 --> 00:32:21.320
in Unity, because there's just
a tremendous number of things.

00:32:21.320 --> 00:32:24.830
But clear flags,
background, culling mask--

00:32:24.830 --> 00:32:29.490
all these things that are relevant
to how the camera does its job--

00:32:29.490 --> 00:32:31.550
they are all things that
we have complete access

00:32:31.550 --> 00:32:32.716
to here in the Unity editor.

00:32:32.716 --> 00:32:36.564
We don't even need to touch code,
really, for a lot of things.

00:32:36.564 --> 00:32:38.480
An interesting fun thing
we can take a look at

00:32:38.480 --> 00:32:43.590
is if we go to Layouts-- go back to two
by three, and take a look at our game

00:32:43.590 --> 00:32:44.090
again.

00:32:44.090 --> 00:32:51.140
So we have our camera currently
looking at the screen here.

00:32:51.140 --> 00:32:52.570
It's just always in one spot.

00:32:52.570 --> 00:32:55.790
And it has a way of
projecting the scene.

00:32:55.790 --> 00:32:57.080
It can do one of two things.

00:32:57.080 --> 00:33:03.020
It can be perspective projection
or orthographic projection.

00:33:03.020 --> 00:33:08.760
Does anybody know what the difference
is between the two, at least visually?

00:33:08.760 --> 00:33:11.520
So perspective
projection-- what that does

00:33:11.520 --> 00:33:15.570
is it models how real cameras, real
lenses, the human eye, et cetera,

00:33:15.570 --> 00:33:17.790
behave in real life.

00:33:17.790 --> 00:33:19.350
Things distort a little bit.

00:33:19.350 --> 00:33:22.290
And so you see things, depending
on where you're looking at them,

00:33:22.290 --> 00:33:27.150
they look wider or skewed, and
not completely geometrical,

00:33:27.150 --> 00:33:31.320
like you would if you were just to
draw them at a certain distance.

00:33:31.320 --> 00:33:34.359
Things have vanishing points, et cetera.

00:33:34.359 --> 00:33:36.150
Orthographic-- things
look a lot different.

00:33:36.150 --> 00:33:40.230
So notice instantly, so we
can see here, perspective

00:33:40.230 --> 00:33:44.550
doesn't really change a whole
lot visually with our helicopter.

00:33:44.550 --> 00:33:46.980
Things do change a little
bit with the background,

00:33:46.980 --> 00:33:50.420
because the view angle is
different between the two--

00:33:50.420 --> 00:33:52.440
the perspective and the
orthographic camera.

00:33:52.440 --> 00:33:55.790
But if we make this a little bit larger.

00:33:55.790 --> 00:33:59.210
So I'm going to increase
the size like that.

00:34:02.550 --> 00:34:05.251
And I play.

00:34:05.251 --> 00:34:06.250
One thing we'll notice--

00:34:06.250 --> 00:34:10.150
what's the first thing
that folks are noticing?

00:34:10.150 --> 00:34:14.620
You can actually see the difference
between the top and the bottom.

00:34:14.620 --> 00:34:16.770
Whoop.

00:34:16.770 --> 00:34:20.840
How, in particular, I'll put your
attention towards the buildings.

00:34:20.840 --> 00:34:22.209
How do the buildings differ?

00:34:22.209 --> 00:34:23.889
AUDIENCE: You can't see the side.

00:34:23.889 --> 00:34:27.590
COLTON OGDEN: You can't
see the side anymore.

00:34:27.590 --> 00:34:30.790
The lens sort of curves a bit.

00:34:30.790 --> 00:34:34.880
And so I'm not entirely familiar
with all the math involved.

00:34:34.880 --> 00:34:38.500
But at the end of the day, what it boils
down to is, with a perspective camera,

00:34:38.500 --> 00:34:40.300
you can actually gauge
things as distance

00:34:40.300 --> 00:34:42.091
relative to each other
a little bit better.

00:34:42.091 --> 00:34:45.170
With a orthographic camera,
everything is completely flat,

00:34:45.170 --> 00:34:47.739
and no matter how far
away from you it is

00:34:47.739 --> 00:34:51.040
on the access that's completely
perpendicular to you,

00:34:51.040 --> 00:34:53.090
it's going to look the exact same.

00:34:53.090 --> 00:34:55.570
So these buildings are always going to
look the exact same, no matter how far

00:34:55.570 --> 00:34:57.611
away they are, no matter
which position they are.

00:34:57.611 --> 00:35:00.700
Because everything is just
looked at completely flat.

00:35:00.700 --> 00:35:06.230
And the view matrix is
calculated in a different way.

00:35:06.230 --> 00:35:09.010
And so, just with a
simple button, you can

00:35:09.010 --> 00:35:12.131
change how your game looks completely.

00:35:12.131 --> 00:35:13.630
You've probably seen a lot of games.

00:35:13.630 --> 00:35:17.320
I believe Crossy Road does everything
with a orthographic camera,

00:35:17.320 --> 00:35:18.970
versus a perspective camera.

00:35:18.970 --> 00:35:21.430
It has a very distinctive
look, especially

00:35:21.430 --> 00:35:23.920
once you skew things a little bit.

00:35:23.920 --> 00:35:26.492
But that's just one thing
that you can change just

00:35:26.492 --> 00:35:28.450
without having to touch
a single line of code--

00:35:28.450 --> 00:35:32.114
how your game looks via just
the camera's implementation.

00:35:32.114 --> 00:35:33.655
Let's take things back to how it was.

00:35:36.066 --> 00:35:38.190
And there's a lot of things
like the field of view.

00:35:38.190 --> 00:35:40.064
So if you want to see
more of the game world.

00:35:40.064 --> 00:35:42.730
So things like in Quake
and other shooters,

00:35:42.730 --> 00:35:46.210
you can change this view,
usually in your menu settings,

00:35:46.210 --> 00:35:49.180
just so you can see more around you.

00:35:49.180 --> 00:35:51.490
And it looks a little like
a fisheye lens a little bit,

00:35:51.490 --> 00:35:52.615
depending on how you do it.

00:35:52.615 --> 00:35:55.761
And that's just more distortion
of the perspective projection.

00:35:58.640 --> 00:35:59.140
Yeah.

00:35:59.140 --> 00:36:00.760
All of these things, they all have--

00:36:00.760 --> 00:36:03.260
I don't know necessarily what
every single one of them does,

00:36:03.260 --> 00:36:05.669
just because there's
just a lot involved.

00:36:05.669 --> 00:36:07.960
And generally, you don't have
to mess with it too much.

00:36:07.960 --> 00:36:11.290
It just ultimately depends on what you
are trying to accomplish in your game.

00:36:11.290 --> 00:36:14.212
And you'll end up finding
specific areas of the editor

00:36:14.212 --> 00:36:16.420
and specific areas of the
code base and documentation

00:36:16.420 --> 00:36:18.190
that you dive deeply into.

00:36:18.190 --> 00:36:23.500
But this essentially is what a
component affords you the ability to do.

00:36:23.500 --> 00:36:26.680
When you create a component and
you attach it to a game object,

00:36:26.680 --> 00:36:29.770
you can easily not only
combine different things

00:36:29.770 --> 00:36:33.640
to create this emergent new
behavior and combination

00:36:33.640 --> 00:36:36.130
of behaviors for your game objects.

00:36:36.130 --> 00:36:40.990
But Unity allows you, via different
ways of programming the components,

00:36:40.990 --> 00:36:45.100
to modify them, depending on how
customizable you want them to be,

00:36:45.100 --> 00:36:46.660
in the editor itself.

00:36:46.660 --> 00:36:49.639
So you don't have to
touch any of this in code.

00:36:49.639 --> 00:36:51.430
You can just go into
the editor and quickly

00:36:51.430 --> 00:36:55.870
whip things up because of the way that
you've modeled all your components.

00:36:55.870 --> 00:36:58.060
And so we see other things
like the audio listener.

00:36:58.060 --> 00:37:01.300
An audio listener is something that
will literally listen for audio,

00:37:01.300 --> 00:37:04.360
and play it back like a
microphone to the game player.

00:37:04.360 --> 00:37:07.030
And then an audio source is
an actual source of audio.

00:37:07.030 --> 00:37:09.670
And so it will play that
audio at the location

00:37:09.670 --> 00:37:11.530
of whatever that game object is.

00:37:11.530 --> 00:37:13.300
So we've combined all these things.

00:37:13.300 --> 00:37:17.320
So now we have a camera that
is projecting everything

00:37:17.320 --> 00:37:19.990
with perspective projection.

00:37:19.990 --> 00:37:24.090
And it's an audio listener, so it's
going to listen for audio in our scene.

00:37:24.090 --> 00:37:29.440
And it's also going to play an
audio source and listen to itself.

00:37:29.440 --> 00:37:30.750
And that's just the beginning.

00:37:30.750 --> 00:37:32.896
We have a whole bunch
of other components

00:37:32.896 --> 00:37:35.020
here, which we can take a
look just really quickly.

00:37:35.020 --> 00:37:39.902
So the directional light
has a light component.

00:37:39.902 --> 00:37:41.860
And so a light, you can
do all kinds of things.

00:37:41.860 --> 00:37:44.660
You can make a spotlight,
directional light, point light.

00:37:44.660 --> 00:37:46.787
All these look a little bit differently.

00:37:46.787 --> 00:37:48.370
You can make it have a specific color.

00:37:48.370 --> 00:37:53.650
So maybe if you wanted a really dark
scene, you could have a dark light.

00:37:53.650 --> 00:37:57.820
Or you could even emulate dawn
or dusk with an orange light.

00:37:57.820 --> 00:38:01.126
That's sort of how you'd
go about doing that.

00:38:01.126 --> 00:38:04.000
You can bake your lighting, which
means that you just pre-compute it,

00:38:04.000 --> 00:38:06.000
so that you don't have
to render it in real time

00:38:06.000 --> 00:38:07.619
when you actually play it on hardware.

00:38:07.619 --> 00:38:09.910
A lot of different things,
a lot of different settings.

00:38:09.910 --> 00:38:11.890
We don't have time necessarily
to go into all of them.

00:38:11.890 --> 00:38:13.750
But looking through
all of these, you can

00:38:13.750 --> 00:38:17.980
see all these game objects are just
combinations of these components.

00:38:17.980 --> 00:38:24.070
And those combinations of components
are responsible for the behavior

00:38:24.070 --> 00:38:25.540
that we get in our game.

00:38:25.540 --> 00:38:29.500
That's the ultimate essence of what
Unity is, and how it does what it does.

00:38:29.500 --> 00:38:32.480
And to illustrate the difference,
we've talked about this before.

00:38:32.480 --> 00:38:35.442
This is an inheritance
chain, where Monster

00:38:35.442 --> 00:38:38.650
inherits from Creature, which then goes
to Goblin, Goblin Chief, Elite Goblin

00:38:38.650 --> 00:38:39.250
Chief.

00:38:39.250 --> 00:38:42.850
In Unity, you could
create a game object,

00:38:42.850 --> 00:38:47.330
and then give it a creature component,
a goblin component, a patrol component--

00:38:47.330 --> 00:38:47.830
right?

00:38:47.830 --> 00:38:52.110
So maybe you want
different things to patrol.

00:38:52.110 --> 00:38:53.860
In Unity, it would be
kind of complicated.

00:38:53.860 --> 00:38:57.760
But you could create
basically a pathway,

00:38:57.760 --> 00:39:02.030
and then have your entity follow
that pathway at a specific time.

00:39:02.030 --> 00:39:04.030
And then, depending on
how you've programmed it,

00:39:04.030 --> 00:39:07.670
you could specify all these different
characteristics in the editor.

00:39:07.670 --> 00:39:09.520
So you could just say
on the editor, OK, I

00:39:09.520 --> 00:39:12.100
want you to go patrol from
this range to this range.

00:39:12.100 --> 00:39:15.610
And I want you to do it with this
length of time, pause for this long--

00:39:15.610 --> 00:39:16.110
right?

00:39:16.110 --> 00:39:18.318
And then you can give that
to anything in your scene.

00:39:18.318 --> 00:39:21.040
You could make a camera
patrol if you wanted to,

00:39:21.040 --> 00:39:24.540
and then have that be demo code
for the beginning of your game.

00:39:24.540 --> 00:39:26.520
The flexibility is just insane.

00:39:26.520 --> 00:39:27.341
Elite component.

00:39:27.341 --> 00:39:27.840
Right?

00:39:27.840 --> 00:39:31.410
If you want, maybe, certain enemies
or certain objects, if they're elite,

00:39:31.410 --> 00:39:32.410
maybe they shine bright.

00:39:32.410 --> 00:39:34.451
And maybe they drop more
experience or something.

00:39:34.451 --> 00:39:38.130
A chief component maybe has better
weaponry than a non-chief component.

00:39:38.130 --> 00:39:41.190
And then a toxic component, maybe,
is an enemy that, when it dies,

00:39:41.190 --> 00:39:46.410
it sprays toxic gas or toxic
liquid all over the place.

00:39:46.410 --> 00:39:48.000
But the flexibility is there.

00:39:48.000 --> 00:39:52.470
You can ascribe any component to any
object to get any sort of behavior

00:39:52.470 --> 00:39:53.240
that you want to.

00:39:53.240 --> 00:39:56.139
It's on you, of course, to implement
all these components, right?

00:39:56.139 --> 00:39:57.930
You're not going to
get all these for free.

00:39:57.930 --> 00:39:59.388
You're going to get a lot for free.

00:39:59.388 --> 00:40:04.360
Unity gives you a ton of
components-- really good components.

00:40:04.360 --> 00:40:07.886
But you're ultimately going to
need to program your game logic.

00:40:07.886 --> 00:40:10.260
And so you'll have to implement
all these things-- elite,

00:40:10.260 --> 00:40:12.660
goblin, what it means
to be all these things.

00:40:12.660 --> 00:40:15.690
But thankfully, it's
not terribly painful.

00:40:15.690 --> 00:40:19.800
The way at which we go about doing
all of this-- and by the way,

00:40:19.800 --> 00:40:23.100
are there any questions so far
as to how Unity's model works,

00:40:23.100 --> 00:40:25.350
the difference between
composition versus inheritance,

00:40:25.350 --> 00:40:28.830
anything we've talked about this far?

00:40:28.830 --> 00:40:30.510
All right.

00:40:30.510 --> 00:40:35.250
The way at which we actually go
about making our own components,

00:40:35.250 --> 00:40:38.655
which is probably what you'll
spend the most of your time doing,

00:40:38.655 --> 00:40:41.280
at least in the beginning, when
you're bootstrapping your game,

00:40:41.280 --> 00:40:45.900
is programming what's
called a MonoBehaviour.

00:40:45.900 --> 00:40:48.610
And so we talked about Mono before.

00:40:48.610 --> 00:40:52.980
So Mono is the open source
implementation of the CLR.

00:40:52.980 --> 00:40:54.271
And MonoBehaviour, I imagine--

00:40:54.271 --> 00:40:56.520
I tried to look this up and
see where it derives from.

00:40:56.520 --> 00:41:03.120
I imagine it's because it was originally
a Mac exclusive project, Unity.

00:41:03.120 --> 00:41:05.910
And so because everything
was implemented in Mono,

00:41:05.910 --> 00:41:11.070
and because this is way it's scripted,
MonoBehaviour became the name.

00:41:11.070 --> 00:41:14.640
But a MonoBehaviour is
what a component is.

00:41:14.640 --> 00:41:16.340
They are effectively one and the same.

00:41:16.340 --> 00:41:18.048
The difference being
that a MonoBehaviour

00:41:18.048 --> 00:41:19.620
is how it's illustrated in code.

00:41:19.620 --> 00:41:23.700
In C#, if you want to program something
to be a component that you can then

00:41:23.700 --> 00:41:28.380
attach to a game object, it needs
to be inherited from MonoBehaviour.

00:41:31.620 --> 00:41:37.260
So if we go to coin spawner, here.

00:41:37.260 --> 00:41:40.080
And you can see the difference
between what's built in to Unity

00:41:40.080 --> 00:41:42.660
and what's your own via--

00:41:42.660 --> 00:41:44.230
it'll say script here.

00:41:44.230 --> 00:41:46.950
So in this case, I have a
coin spawner object, right?

00:41:46.950 --> 00:41:51.090
It's just an empty object, at
least in terms of what it displays.

00:41:51.090 --> 00:41:53.410
It's got a transform,
which is irrelevant.

00:41:53.410 --> 00:41:56.610
It could be literally
anywhere in our entire scene.

00:41:56.610 --> 00:42:00.240
The only difference between
this and the empty game

00:42:00.240 --> 00:42:04.260
object that we saw before is
that it has a coin spawner.

00:42:04.260 --> 00:42:10.590
And this coin spawner
has this thing here.

00:42:10.590 --> 00:42:14.700
All components that you add would
have this script field here,

00:42:14.700 --> 00:42:17.070
just to show you that
that's the script that it's

00:42:17.070 --> 00:42:19.560
getting it's code behavior from.

00:42:19.560 --> 00:42:25.350
But also, we have this field here
called prefabs, which has a size of 1.

00:42:25.350 --> 00:42:29.850
And it's actually calculated
based on how many elements

00:42:29.850 --> 00:42:32.610
the list that it's responsible for has.

00:42:32.610 --> 00:42:35.110
And we have one element,
as it says, here.

00:42:35.110 --> 00:42:38.667
And it's got a coin
pre-fab, which is here.

00:42:38.667 --> 00:42:40.000
And notice that I clicked on it.

00:42:40.000 --> 00:42:42.435
It took me right to it in my assets.

00:42:42.435 --> 00:42:45.060
And so prefabs and all of that--
what that means and how to get

00:42:45.060 --> 00:42:47.460
that all working--
we'll talk about that.

00:42:47.460 --> 00:42:54.660
But a coin spawner script
has to exist in our code base

00:42:54.660 --> 00:42:58.440
before we can actually add it
to any game objects, right?

00:42:58.440 --> 00:43:02.610
So in my project I do have--

00:43:02.610 --> 00:43:06.870
usually, you have assets, a folder
called Assets in your Unity Project.

00:43:06.870 --> 00:43:09.240
And then I typically
create a Resources folder.

00:43:09.240 --> 00:43:12.070
It's not mandatory that you do so,
but just for organization, I'll

00:43:12.070 --> 00:43:14.442
create a Resources.

00:43:14.442 --> 00:43:17.400
And then I'll have a bunch of folders
for all sorts of different things

00:43:17.400 --> 00:43:18.358
like we've done before.

00:43:18.358 --> 00:43:21.180
Where in the Love2D project,
at the parent level,

00:43:21.180 --> 00:43:27.750
you have like a Fonts, a Music or
Sounds, and then a source directory.

00:43:27.750 --> 00:43:30.510
In this case we have
Fonts, Materials, Models,

00:43:30.510 --> 00:43:33.120
all the different assets that
we will need in our game,

00:43:33.120 --> 00:43:35.040
but also a Scripts folder.

00:43:35.040 --> 00:43:41.970
And all the C# scripts here that we'll
use amongst all of our components--

00:43:41.970 --> 00:43:43.470
all of our game objects.

00:43:43.470 --> 00:43:46.020
And so you could easily
just go to any of these,

00:43:46.020 --> 00:43:50.910
rather than have to go into your
operating system, open up a new window,

00:43:50.910 --> 00:43:53.790
and find your file, and
navigate through all the files

00:43:53.790 --> 00:43:56.910
that Unity generates for you,
which can be kind of a pain.

00:43:56.910 --> 00:43:59.940
You can just double-click on
a coin script, for example.

00:43:59.940 --> 00:44:02.640
And it'll open in your default editor.

00:44:02.640 --> 00:44:06.210
And so one thing that
I'll just mention here

00:44:06.210 --> 00:44:08.850
is, if you go to your
Unity preferences--

00:44:08.850 --> 00:44:11.002
on Mac, it's Unity
and then Preferences--

00:44:11.002 --> 00:44:12.210
you can go to External Tools.

00:44:12.210 --> 00:44:15.510
So by default, starting in 2018,
Unity is transitioning away

00:44:15.510 --> 00:44:19.649
from its prior IDE, which was called
MonoDevelop, which was a good IDE.

00:44:19.649 --> 00:44:21.690
There's transitioning away
from that, and they're

00:44:21.690 --> 00:44:26.970
making it focused on Visual
Studio as the default IDE.

00:44:26.970 --> 00:44:28.170
I don't use Visual Studio.

00:44:28.170 --> 00:44:29.580
I like VS Code.

00:44:29.580 --> 00:44:33.000
So what I did was-- and
what you can do is--

00:44:33.000 --> 00:44:35.724
you can choose your
external script editor here,

00:44:35.724 --> 00:44:37.890
if you prefer a different
script editor-- like Atom,

00:44:37.890 --> 00:44:40.330
or VS Code, or Sublime Text.

00:44:40.330 --> 00:44:42.665
And then just browse for
it on your file system,

00:44:42.665 --> 00:44:44.790
whether you're on a Windows,
Linux, or Mac machine.

00:44:44.790 --> 00:44:47.123
And then you can easily just
choose which file you want.

00:44:47.123 --> 00:44:48.670
In this case, I chose VS Code.

00:44:48.670 --> 00:44:50.610
And so that effect that
that has is, whenever

00:44:50.610 --> 00:44:53.130
I double-click on a
script within Unity, it

00:44:53.130 --> 00:44:56.370
will actually open
the IDE or text editor

00:44:56.370 --> 00:45:00.630
that I have assigned to
it in Unity's preferences.

00:45:00.630 --> 00:45:08.220
And so here is the Coin component
that I have created for this example.

00:45:08.220 --> 00:45:13.440
And notice that every component,
first of all, is a class.

00:45:13.440 --> 00:45:20.370
And actually, everything effectively
in C#, just as in Java, is a class.

00:45:20.370 --> 00:45:21.790
It's a public class.

00:45:21.790 --> 00:45:26.710
And notice that I call it Coin, and I
got this colon, and then MonoBehaviour.

00:45:26.710 --> 00:45:30.630
So this colon-- anybody know, anybody
take a guess what the colon means?

00:45:30.630 --> 00:45:31.130
Tony?

00:45:31.130 --> 00:45:31.845
TONY: Extends.

00:45:31.845 --> 00:45:32.970
COLTON OGDEN: Extends, yes.

00:45:32.970 --> 00:45:36.525
Extends or inherits from MonoBehaviour.

00:45:36.525 --> 00:45:38.400
So anytime you have a
component that you want

00:45:38.400 --> 00:45:41.970
to create, you want to add it to Unity,
and allow you to see it in the editor,

00:45:41.970 --> 00:45:45.430
and allow you to actually
drive behavior of an object,

00:45:45.430 --> 00:45:47.670
you need to inherit from MonoBehaviour.

00:45:47.670 --> 00:45:52.680
Like it says here on my VS Code, since
I have the extension for OmniSharp,

00:45:52.680 --> 00:45:55.410
it will actually tell me,
MonoBehaviour is the base class

00:45:55.410 --> 00:45:59.547
from which every Unity script derives.

00:45:59.547 --> 00:46:00.880
There's a couple of things here.

00:46:00.880 --> 00:46:03.450
So notice that we have a few methods.

00:46:03.450 --> 00:46:10.320
So void Start, void Update,
and void OnTriggerEnter.

00:46:10.320 --> 00:46:12.609
So anybody take a guess as to what--

00:46:12.609 --> 00:46:14.400
ignoring OnTriggerEnter--
does anybody have

00:46:14.400 --> 00:46:16.784
a guess as to what Start and Update do?

00:46:16.784 --> 00:46:17.768
Yeah.

00:46:17.768 --> 00:46:21.220
AUDIENCE: Could it be just like that
and [INAUDIBLE] update [INAUDIBLE]??

00:46:21.220 --> 00:46:22.281
COLTON OGDEN: Sorry,
say it one more time.

00:46:22.281 --> 00:46:24.870
AUDIENCE: Would it just [INAUDIBLE]
an update or [INAUDIBLE]??

00:46:24.870 --> 00:46:25.786
COLTON OGDEN: Exactly.

00:46:25.786 --> 00:46:29.490
It would be just like we did
before when we created objects

00:46:29.490 --> 00:46:35.220
in our Love2D projects, where we had an
init function assigned to every class,

00:46:35.220 --> 00:46:37.250
and an update function
assigned to every class.

00:46:37.250 --> 00:46:39.090
And we would call those ourselves.

00:46:39.090 --> 00:46:44.070
Every MonoBehaviour can
have a Start method.

00:46:44.070 --> 00:46:46.800
In this case, it's empty,
because every time you

00:46:46.800 --> 00:46:50.190
create a new script by the Unity editor,
it will automatically-- first of all,

00:46:50.190 --> 00:46:53.390
it will automatically create
a brand new file for you.

00:46:53.390 --> 00:46:55.530
So let's just say I want
to create a new script.

00:46:55.530 --> 00:46:58.500
So if I'm in the Unity editor,
and I go to my assets--

00:46:58.500 --> 00:47:00.720
I right-click Create.

00:47:00.720 --> 00:47:03.160
And then I want to
create a new C# script.

00:47:03.160 --> 00:47:04.830
It'll create it there.

00:47:04.830 --> 00:47:06.480
I can say, maybe I want this to be--

00:47:06.480 --> 00:47:08.880
I don't know-- Test Component, right?

00:47:11.430 --> 00:47:15.870
So this should have the effect
of, when I open it in my VS Code,

00:47:15.870 --> 00:47:18.330
this Test Component-- this
was auto generated for us.

00:47:18.330 --> 00:47:20.340
We didn't have to write
any of this boilerplate.

00:47:20.340 --> 00:47:26.850
But every script that
you create, by default,

00:47:26.850 --> 00:47:29.805
is a MonoBehaviour, which it
strictly does not have to be.

00:47:29.805 --> 00:47:34.034
You could create a class of your own,
that maybe you call behind the scenes,

00:47:34.034 --> 00:47:36.450
or maybe it just represents a
data structure or something.

00:47:36.450 --> 00:47:39.810
But by default, anytime you
create a new script in Unity,

00:47:39.810 --> 00:47:43.200
it'll save you the hassle of
typing out all this stuff by hand.

00:47:43.200 --> 00:47:48.380
And it'll give you an empty Start
method and an empty Update method.

00:47:48.380 --> 00:47:53.130
And so, like Tony said, the Start
method gets called as soon as the object

00:47:53.130 --> 00:47:55.980
that it's assigned to gets instantiated.

00:47:55.980 --> 00:47:59.640
Well, as soon as this component
gets instantiated, rather.

00:47:59.640 --> 00:48:03.750
Which often is the case
that it gets instantiated

00:48:03.750 --> 00:48:05.490
at the same time as a game object.

00:48:05.490 --> 00:48:06.020
Not always.

00:48:06.020 --> 00:48:10.140
You can create game
components on the fly.

00:48:10.140 --> 00:48:12.535
But this Start method will get called.

00:48:12.535 --> 00:48:14.910
Anything that you put in here
will get called right away.

00:48:14.910 --> 00:48:17.640
And then this Update method,
Unity will-- every frame,

00:48:17.640 --> 00:48:20.760
go through every component
on every live game object--

00:48:20.760 --> 00:48:26.010
and will call the code that's
contained within this Update function.

00:48:26.010 --> 00:48:28.140
And you don't have to call
this anywhere yourself.

00:48:28.140 --> 00:48:34.410
Just by assigning this component
to a game object in your scene,

00:48:34.410 --> 00:48:38.460
you get the update, and start,
and all this other functionality

00:48:38.460 --> 00:48:40.110
given to you for free.

00:48:40.110 --> 00:48:43.140
And MonoBehaviours are
actually much more complex

00:48:43.140 --> 00:48:48.190
than just Start and Update.

00:48:48.190 --> 00:48:56.650
So if you go to MonoBehaviour
here, we can see that--

00:48:56.650 --> 00:48:59.440
by the way, I want to shout
out Unity's documentation.

00:48:59.440 --> 00:49:01.780
Unity has amazing documentation--

00:49:01.780 --> 00:49:02.790
docs.unity3d.com.

00:49:02.790 --> 00:49:05.610
You will go through
pretty much everything

00:49:05.610 --> 00:49:10.600
you possibly could ever want with every
object implemented in Unity, in quite

00:49:10.600 --> 00:49:12.886
a good detail, with a lot of examples.

00:49:12.886 --> 00:49:14.760
But here we can see,
just in the description,

00:49:14.760 --> 00:49:23.010
it will tell us, the MonoBehaviour will
get start, update, fixed update, late

00:49:23.010 --> 00:49:26.859
update, on GUI-- all of these
functions called for us, assuming

00:49:26.859 --> 00:49:27.900
that they're implemented.

00:49:27.900 --> 00:49:30.316
And you don't have to implement
them if you don't want to.

00:49:30.316 --> 00:49:32.469
If they're not implemented,
they just won't happen.

00:49:32.469 --> 00:49:34.260
If there's no start
method, then that means

00:49:34.260 --> 00:49:35.710
there's no start logic
for this component.

00:49:35.710 --> 00:49:37.050
So it doesn't need to execute.

00:49:37.050 --> 00:49:39.420
If there's no update, maybe it just
needs to start at the very beginning,

00:49:39.420 --> 00:49:41.760
but never update after that,
don't implement update.

00:49:41.760 --> 00:49:44.880
And update will not be called.

00:49:44.880 --> 00:49:46.680
All of these are optional.

00:49:46.680 --> 00:49:48.570
That's just a small
chunk of MonoBehaviour,

00:49:48.570 --> 00:49:51.540
though, because you also have messages.

00:49:51.540 --> 00:49:56.610
So messages are functions
that you override.

00:49:56.610 --> 00:49:59.650
As you can see, there's
a whole lot of them.

00:49:59.650 --> 00:50:02.760
And all of these messages get called,
depending on certain things that

00:50:02.760 --> 00:50:04.770
happen in the game scene.

00:50:04.770 --> 00:50:12.690
So OnTriggerEnter, for example, if our
object is a trigger, and we enter it,

00:50:12.690 --> 00:50:15.750
then the behavior will get
called in that function, which

00:50:15.750 --> 00:50:20.340
will allow us to do things like--
if our helicopter enters a building,

00:50:20.340 --> 00:50:22.350
we can call that
helicopter's explode method,

00:50:22.350 --> 00:50:26.790
which is literally what we do in this
project, thanks to this function.

00:50:26.790 --> 00:50:29.420
And all we really need to do is
just a couple of lines of code.

00:50:29.420 --> 00:50:31.080
It's very simple.

00:50:31.080 --> 00:50:34.250
OnPostRender, OnPreRender--
all these different things

00:50:34.250 --> 00:50:35.500
are called at different times.

00:50:35.500 --> 00:50:38.499
You can look into all of these, if
you want to, just by clicking on them

00:50:38.499 --> 00:50:41.070
and looking at their documentation.

00:50:41.070 --> 00:50:44.070
LateUpdate is called after all
update functions have been called.

00:50:44.070 --> 00:50:49.560
This can be relevant for
certain physics calculations.

00:50:49.560 --> 00:50:53.760
But there's a whole lot of
different things you can do.

00:50:53.760 --> 00:50:56.490
You don't necessarily need to
do a lot of things yourself,

00:50:56.490 --> 00:50:59.370
if Unity provides you with
the function that gives you

00:50:59.370 --> 00:51:00.970
the effect that you're looking for.

00:51:00.970 --> 00:51:03.880
And so if you're curious, MonoBehaviour,
and then the docs at large.

00:51:03.880 --> 00:51:07.200
This is just all the documentation--
just an insane amount of documentation.

00:51:07.200 --> 00:51:09.640
And that's just in the classes.

00:51:09.640 --> 00:51:14.470
There's all these other
little side areas, as well.

00:51:14.470 --> 00:51:17.352
And so that's sort of
what MonoBehaviour is.

00:51:17.352 --> 00:51:18.060
It's a component.

00:51:18.060 --> 00:51:20.526
It gets a lot of these
functions called for you.

00:51:20.526 --> 00:51:21.900
You don't have to implement them.

00:51:21.900 --> 00:51:26.160
But if you do, you get a lot of
functionality for free, basically.

00:51:26.160 --> 00:51:30.450
Any questions as to what a MonoBehaviour
is, how it works, and so forth?

00:51:30.450 --> 00:51:37.150
Or any of the syntax we've seen thus
far for creating a MonoBehaviour?

00:51:37.150 --> 00:51:38.240
All right.

00:51:38.240 --> 00:51:42.090
And so, here in our coin, for example,
which we were looking at before,

00:51:42.090 --> 00:51:45.300
notice that I'm referencing
something called a transform.

00:51:45.300 --> 00:51:51.780
Transform.position.x is less than
negative 25, destroy a game object.

00:51:51.780 --> 00:51:54.983
If this is the coin, what do we
think that this is accomplishing?

00:51:57.804 --> 00:51:59.720
AUDIENCE: It goes off
the screen [INAUDIBLE]??

00:51:59.720 --> 00:52:00.960
COLTON OGDEN: Yep.

00:52:00.960 --> 00:52:06.480
So the transform,
recall, was our component

00:52:06.480 --> 00:52:09.450
that encapsulates our
rotation, scale, and position.

00:52:09.450 --> 00:52:13.530
So we can just say, if
transform.position.x is less

00:52:13.530 --> 00:52:17.280
than negative 25, destroy game object.

00:52:17.280 --> 00:52:19.320
Because we're spawning
the coins dynamically.

00:52:19.320 --> 00:52:22.020
When they get off screen-- just like
we did with the pipes, if you remember.

00:52:22.020 --> 00:52:23.978
And I had a screenshot,
actually, in that slide

00:52:23.978 --> 00:52:25.770
that showcased what that looked like.

00:52:25.770 --> 00:52:29.940
We can see that exact thing live here.

00:52:29.940 --> 00:52:33.450
If I go to Layouts, two by three,
and we play the game again,

00:52:33.450 --> 00:52:37.340
and then I'll just die at some point.

00:52:37.340 --> 00:52:42.741
But if we do this, we're
seeing our scene live.

00:52:42.741 --> 00:52:43.990
So we're following this-- yep.

00:52:43.990 --> 00:52:46.920
See how the coin-- as soon as
the building, and the plane,

00:52:46.920 --> 00:52:48.570
and the coins all get to this point--

00:52:48.570 --> 00:52:53.875
this is negative 25 in
Unity units, not in pixels.

00:52:53.875 --> 00:52:56.500
Everything in Unity is based on
Unity units, which, by default,

00:52:56.500 --> 00:53:02.310
1 is equal to one meter, as opposed to--
we've been thus far using just pixels.

00:53:02.310 --> 00:53:07.152
But pixels aren't viable in 3D.

00:53:07.152 --> 00:53:10.291
[MUSIC PLAYING]

00:53:10.291 --> 00:53:12.290
But that's effectively
what that component does.

00:53:12.290 --> 00:53:16.010
It's checking, in our Update
function-- void Update--

00:53:16.010 --> 00:53:20.300
if transform.position.x
less than negative 25.

00:53:20.300 --> 00:53:23.090
And notice that we don't actually
have to declare transform

00:53:23.090 --> 00:53:26.000
anywhere, which is interesting.

00:53:26.000 --> 00:53:28.130
That's because MonoBehaviour,
by default, gives you

00:53:28.130 --> 00:53:32.000
access to its game objects
transform just by default.

00:53:32.000 --> 00:53:35.270
That's just something you get for free.

00:53:35.270 --> 00:53:39.500
And then, notice gameObject-- we also
haven't declared gameObject anywhere.

00:53:39.500 --> 00:53:42.050
Because by default, we
have access to gameObject.

00:53:42.050 --> 00:53:46.330
It's the game object that
this script belongs to.

00:53:46.330 --> 00:53:48.058
That this component belongs to.

00:53:48.058 --> 00:53:50.930
AUDIENCE: [INAUDIBLE]

00:53:50.930 --> 00:53:54.170
COLTON OGDEN: This would be the actual--

00:53:54.170 --> 00:53:57.980
so the interesting
thing about the classes

00:53:57.980 --> 00:54:00.920
is, you don't have to
explicitly say this.

00:54:00.920 --> 00:54:08.490
Because if you had int myNumber equals
10, and you just say, myNumber--

00:54:08.490 --> 00:54:12.260
the difference between Lua
and C# and Java is that,

00:54:12.260 --> 00:54:16.070
it will already know what
myNumber is, this is myNumber.

00:54:16.070 --> 00:54:17.535
It will know its this objects.

00:54:17.535 --> 00:54:18.160
AUDIENCE: Yeah.

00:54:18.160 --> 00:54:19.826
COLTON OGDEN: You don't have to do that.

00:54:23.000 --> 00:54:26.870
Sort of a nice little thing to
save you a little bit of time.

00:54:26.870 --> 00:54:30.500
Because you could then just
say, myNumber plus equals 10.

00:54:30.500 --> 00:54:33.710
Another nice thing about C#, by the
way, which we didn't get in Lua--

00:54:33.710 --> 00:54:36.051
you can do compound
assignment operators.

00:54:36.051 --> 00:54:38.300
So you can do plus equals,
minus equals, times equals.

00:54:38.300 --> 00:54:40.890
That's one of my little
pet peeves I have with--

00:54:40.890 --> 00:54:41.390
oh.

00:54:41.390 --> 00:54:43.806
And notice that also, the nice
thing about the fact that I

00:54:43.806 --> 00:54:45.220
have OmniSharp-- it'll underline.

00:54:45.220 --> 00:54:48.410
And this is just a trait
of most IDEs, honestly.

00:54:48.410 --> 00:54:50.660
So you get this with a lot of places.

00:54:50.660 --> 00:54:55.994
But it'll tell you myNumber is not
assigned, with the underlining,

00:54:55.994 --> 00:54:57.410
and also just by hovering over it.

00:54:57.410 --> 00:55:00.650
The named myNumber does not
exist in the current context.

00:55:00.650 --> 00:55:03.260
But I can just say, int myNumber.

00:55:03.260 --> 00:55:05.480
And then it's gone.

00:55:05.480 --> 00:55:07.430
A little bit more that
we have to worry about,

00:55:07.430 --> 00:55:09.950
and a little bit less that
we have to worry about.

00:55:09.950 --> 00:55:12.300
A little give and take.

00:55:12.300 --> 00:55:16.040
But still, I think, overall, C# is
going to be a lot more syntax-heavy.

00:55:16.040 --> 00:55:19.820
You do have to worry about things
like braces, and semi-colons,

00:55:19.820 --> 00:55:23.020
and putting everything in a boilerplate.

00:55:23.020 --> 00:55:26.570
And then, obviously, type declaration,
and return type declaration.

00:55:26.570 --> 00:55:29.810
It can be a little bit more than
we've gotten used to so far.

00:55:29.810 --> 00:55:34.190
But it's honestly not too bad,
just given that you can use IDEs.

00:55:34.190 --> 00:55:37.610
First of all, the fact that you're
statically typing everything,

00:55:37.610 --> 00:55:40.040
you can detect a lot
more errors in advance.

00:55:40.040 --> 00:55:42.664
If you're trying to do
something with some type

00:55:42.664 --> 00:55:45.080
that you're not supposed to
do, like some function accepts

00:55:45.080 --> 00:55:48.230
some object of some type, but
you're passing in some other object,

00:55:48.230 --> 00:55:50.620
you'll catch that in advance.

00:55:50.620 --> 00:55:53.760
And so that's a really nice thing.

00:55:53.760 --> 00:55:54.260
But yeah.

00:55:54.260 --> 00:55:57.440
It is a give and take.

00:55:57.440 --> 00:56:00.770
And also, IDEs will
give you, like I said,

00:56:00.770 --> 00:56:03.470
a lot of the functionality-- a
lot of the autocomplete-- that

00:56:03.470 --> 00:56:05.342
makes a lot of this more sustainable.

00:56:05.342 --> 00:56:08.550
And it's not to say, of course, that
Lua and Love2D don't have their own IDE.

00:56:08.550 --> 00:56:11.637
Like ZeroBrane Studio is
popular, from what I understand.

00:56:11.637 --> 00:56:12.470
Haven't used it yet.

00:56:12.470 --> 00:56:16.930
But particularly when you venture into
Java, and C#, and compiled languages,

00:56:16.930 --> 00:56:20.890
static languages-- having those
features does save you a lot more time,

00:56:20.890 --> 00:56:23.390
relatively speaking, than when
you're in a dynamic language.

00:56:25.920 --> 00:56:28.730
So that's what MonoBehaviours are.

00:56:28.730 --> 00:56:32.720
Every component of our game
effectively has-- like the helicopter

00:56:32.720 --> 00:56:35.330
has its own script, a Heli Controller.

00:56:35.330 --> 00:56:38.450
The coin has its own script-- the
Coin Spawner, the Skyscraper Spawner,

00:56:38.450 --> 00:56:39.546
the Skyscraper--

00:56:39.546 --> 00:56:42.170
they all have their own scripts
that drive their game behavior.

00:56:42.170 --> 00:56:46.490
But they also have scripts and
components that are part of Unity core,

00:56:46.490 --> 00:56:48.110
as well.

00:56:48.110 --> 00:56:50.280
Including Colliders and Triggers.

00:56:50.280 --> 00:56:52.370
So if I'm looking in Unity--

00:56:52.370 --> 00:56:54.350
so I'm going to go to--

00:56:54.350 --> 00:56:57.530
and this will actually be the last
thing we look at before we take a break.

00:56:57.530 --> 00:57:03.380
But if I'm in Unity, and I'm going
to go back to my default layout,

00:57:03.380 --> 00:57:06.830
just because it's a
little cramped on a 720p.

00:57:06.830 --> 00:57:09.530
Go to my helicopter.

00:57:09.530 --> 00:57:11.450
Helicopter's got a
couple of pieces to it.

00:57:11.450 --> 00:57:15.000
So let's actually go to
where I can see it here.

00:57:15.000 --> 00:57:17.630
So one of the awesome
things I love about Unity

00:57:17.630 --> 00:57:23.690
is, it gives you a lot of this editor
magic-- this editor sort of sugar.

00:57:23.690 --> 00:57:27.590
It shows you visually where a lot of
the things are in your game world.

00:57:27.590 --> 00:57:31.551
So the green rectangles-- anybody
know what those are, or can guess?

00:57:31.551 --> 00:57:32.384
AUDIENCE: Hit boxes?

00:57:32.384 --> 00:57:33.180
COLTON OGDEN: Yep.

00:57:33.180 --> 00:57:34.030
Hit boxes.

00:57:34.030 --> 00:57:36.500
Exactly.

00:57:36.500 --> 00:57:38.900
These are colliders.

00:57:38.900 --> 00:57:41.750
So the blades-- it
doesn't have a collider.

00:57:41.750 --> 00:57:44.510
That blades collider
is actually separate.

00:57:44.510 --> 00:57:50.630
The box collider here is
this collider right here.

00:57:50.630 --> 00:57:53.454
And so a collider is
literally just something

00:57:53.454 --> 00:57:54.870
that collides with something else.

00:57:54.870 --> 00:57:56.870
And you can set it to
be a trigger or not.

00:57:56.870 --> 00:58:02.930
If it's a trigger, then it actually
won't trigger the OnTriggerCallback

00:58:02.930 --> 00:58:07.710
function that we briefly saw earlier.

00:58:07.710 --> 00:58:10.860
So the things that you
want to activate triggers,

00:58:10.860 --> 00:58:12.360
you should make those not triggers.

00:58:12.360 --> 00:58:15.760
And then triggers, all you have to do is
just click this little Trigger button.

00:58:15.760 --> 00:58:19.190
So what a trigger is is just a
region that you've determined--

00:58:19.190 --> 00:58:22.020
or some object that you've
determined-- should cause behavior

00:58:22.020 --> 00:58:23.700
when it gets triggered.

00:58:23.700 --> 00:58:27.420
So in this case, I've assigned--

00:58:30.390 --> 00:58:33.930
actually, I'll just play it.

00:58:33.930 --> 00:58:39.170
But the airplane has a trigger, right?

00:58:44.190 --> 00:58:48.930
All of these things have colliders,
whether they're triggers or not.

00:58:48.930 --> 00:58:51.930
The helicopter-- its
blades and its body--

00:58:51.930 --> 00:58:55.860
there are two colliders, two boxes.

00:58:55.860 --> 00:58:57.810
The coins all have colliders.

00:58:57.810 --> 00:59:00.900
The skyscrapers will have colliders,
and the airplanes have colliders.

00:59:00.900 --> 00:59:06.220
The difference is that-- oh, and
by the way, another cool thing.

00:59:06.220 --> 00:59:08.810
It's easy to get very
sidetracked, just because there's

00:59:08.810 --> 00:59:10.560
so many cool things to talk about.

00:59:10.560 --> 00:59:12.430
You can pause the game
while it's running.

00:59:12.430 --> 00:59:17.500
So it's paused right now, but it's
in the exact state that I left it.

00:59:17.500 --> 00:59:18.990
So there's three coins there.

00:59:18.990 --> 00:59:20.190
I got my helicopter there.

00:59:20.190 --> 00:59:21.600
I can freely go about the scene.

00:59:21.600 --> 00:59:23.070
I can analyze things.

00:59:23.070 --> 00:59:26.980
I can actually modify this in real time.

00:59:26.980 --> 00:59:30.630
So I can change its
rotation, if I want to.

00:59:30.630 --> 00:59:32.559
Probably don't want to do that.

00:59:32.559 --> 00:59:33.600
But I could if I want to.

00:59:33.600 --> 00:59:35.700
I can change its position, right?

00:59:35.700 --> 00:59:37.450
So I can move it left
to right, like that.

00:59:37.450 --> 00:59:39.741
And notice that I actually
have just the body selected,

00:59:39.741 --> 00:59:42.111
so the blades are kind of separate.

00:59:42.111 --> 00:59:43.860
I don't even know what
kind of crazy stuff

00:59:43.860 --> 00:59:45.840
would happen if I just messed
with this and just let it run.

00:59:45.840 --> 00:59:47.214
I haven't tested it that crazily.

00:59:47.214 --> 00:59:49.480
But you are allowed to step through.

00:59:49.480 --> 00:59:49.980
Oh, OK.

00:59:49.980 --> 00:59:51.360
It looks like they both just go.

00:59:51.360 --> 00:59:54.360
Oh, yeah, because they're
parented to the helicopter object.

00:59:54.360 --> 00:59:56.250
So they're both going to align.

00:59:56.250 --> 00:59:58.950
They're going to move
at the exact same rate,

00:59:58.950 --> 01:00:02.220
regardless of how far apart they are.

01:00:02.220 --> 01:00:03.720
The individual objects.

01:00:03.720 --> 01:00:08.010
But you can just step through your
game's execution frame by frame,

01:00:08.010 --> 01:00:09.839
and get a sense of--

01:00:09.839 --> 01:00:11.880
if you're trying to pinpoint
a bug, maybe, that's

01:00:11.880 --> 01:00:13.325
position-based or
something that's tricky

01:00:13.325 --> 01:00:15.950
and you just haven't been able
to find exactly what's going on.

01:00:19.156 --> 01:00:21.030
You can look through
your whole scene and all

01:00:21.030 --> 01:00:26.506
of the fields of every
object in step time,

01:00:26.506 --> 01:00:28.380
just by stepping through--
this button here--

01:00:28.380 --> 01:00:29.910
assuming that you're in pause mode.

01:00:29.910 --> 01:00:32.460
And then just looking at all the
components here on the right side.

01:00:32.460 --> 01:00:34.020
Because those will all still update.

01:00:34.020 --> 01:00:37.050
All these fields will
update any time you perform

01:00:37.050 --> 01:00:40.590
any changes in the actual scene.

01:00:40.590 --> 01:00:42.570
So super helpful for debugging.

01:00:42.570 --> 01:00:44.010
I know I've used it a bunch.

01:00:44.010 --> 01:00:46.630
And then if I start
again, or if I stop it,

01:00:46.630 --> 01:00:49.170
the nice thing is, any
of the changes that you

01:00:49.170 --> 01:00:51.920
make while it's running
to your object, they

01:00:51.920 --> 01:00:54.930
don't get applied when you
actually go back to the game.

01:00:54.930 --> 01:00:59.104
So notice that I messed with the
two pieces, I separated them.

01:00:59.104 --> 01:01:00.270
And then I stopped the game.

01:01:00.270 --> 01:01:04.120
It ended up going right back to
where it was in the very beginning.

01:01:04.120 --> 01:01:06.820
So all this gets just basically
saved like a snapshot.

01:01:06.820 --> 01:01:10.080
You can do whatever you want during
your game, and then come back to it,

01:01:10.080 --> 01:01:12.440
and it will all get reverted
back to where it was.

01:01:12.440 --> 01:01:12.951
Yeah.

01:01:12.951 --> 01:01:15.306
TONY: So [INAUDIBLE] if
you hit single player,

01:01:15.306 --> 01:01:20.190
and I kept making changes while
I'm not involved [INAUDIBLE]..

01:01:20.190 --> 01:01:20.940
COLTON OGDEN: Yes.

01:01:20.940 --> 01:01:21.720
So, yeah.

01:01:21.720 --> 01:01:24.011
Tony just basically echoed
what I just said, which was,

01:01:24.011 --> 01:01:27.270
if you make changes in your
game while it's running,

01:01:27.270 --> 01:01:31.020
and you're trying to maybe tweak them
such that it's perfect when you're

01:01:31.020 --> 01:01:32.580
actually done, they don't get saved.

01:01:32.580 --> 01:01:36.600
So you have to actually make a conscious
effort to remember what you've done,

01:01:36.600 --> 01:01:40.830
how you've changed different fields,
to fix any bugs, if they do exist.

01:01:40.830 --> 01:01:45.400
But it is something that can be
disheartening or frustrating, if you

01:01:45.400 --> 01:01:48.150
finally fix something, and then
you forget what it is you changed.

01:01:48.150 --> 01:01:50.350
And then you have to mess
with it a whole bunch.

01:01:50.350 --> 01:01:52.350
So remember all the changes
you make, if they're

01:01:52.350 --> 01:01:53.970
pertinent to your
actual game's execution

01:01:53.970 --> 01:01:55.320
and the debugging of your game.

01:01:58.170 --> 01:02:02.700
And then there's also a
console, as well, which is nice.

01:02:02.700 --> 01:02:08.550
If you want to output things
like JavaScript style on the web,

01:02:08.550 --> 01:02:09.810
you can do console.log.

01:02:09.810 --> 01:02:13.410
You can do the same thing with
a debug call here in Unity.

01:02:13.410 --> 01:02:16.620
I don't have any of those
calls in the actual game.

01:02:16.620 --> 01:02:19.347
But it is something that
we'll look at going forward.

01:02:19.347 --> 01:02:21.180
And it is something
that can be very helpful

01:02:21.180 --> 01:02:24.660
if you want to measure something
or output something that you can't

01:02:24.660 --> 01:02:26.202
necessarily look at in the inspector.

01:02:26.202 --> 01:02:29.243
In the case of this game, most of
anything that we want to take a look at

01:02:29.243 --> 01:02:30.570
is visible in the inspector.

01:02:30.570 --> 01:02:36.120
But if you have an algorithm, maybe
you have a generator that's not visual,

01:02:36.120 --> 01:02:37.380
like a level generator.

01:02:37.380 --> 01:02:41.040
And you want to make sure that the
data structure representing your level

01:02:41.040 --> 01:02:44.840
is generating things properly, you can
output everything maybe via hashmarks

01:02:44.840 --> 01:02:46.590
or something in your
console, and actually

01:02:46.590 --> 01:02:48.810
see it that way when
you're running the code,

01:02:48.810 --> 01:02:52.460
rather than having to run the actual
game and look through it that way.

01:02:52.460 --> 01:02:55.230
Some things just are hard
to model in the editor,

01:02:55.230 --> 01:02:57.310
and still need console output.

01:02:57.310 --> 01:02:59.890
So the console is there to help you.

01:02:59.890 --> 01:03:02.980
And so debug.log is the
function, I believe,

01:03:02.980 --> 01:03:07.150
that you need to see all that stuff.

01:03:07.150 --> 01:03:07.650
Right.

01:03:07.650 --> 01:03:08.640
Colliders and triggers.

01:03:08.640 --> 01:03:10.390
So we had a little bit
of a tangent there,

01:03:10.390 --> 01:03:14.684
but the helicopter is comprised
of these three things.

01:03:14.684 --> 01:03:16.600
But the blades collider
should have ultimately

01:03:16.600 --> 01:03:18.580
been merged with the blades object here.

01:03:18.580 --> 01:03:21.610
But we can think of it as
the blades and the body.

01:03:21.610 --> 01:03:26.470
The reason they're separated-- well,
there's two reasons they're separated.

01:03:26.470 --> 01:03:30.010
One core reason they're separated
is they're just different sizes.

01:03:30.010 --> 01:03:32.300
So the blades are longer than the body.

01:03:32.300 --> 01:03:35.500
And so we have, for that
reason, two separate colliders.

01:03:35.500 --> 01:03:38.800
So we're looking at the helicopter here.

01:03:38.800 --> 01:03:42.850
We can see that the
collider for the blades

01:03:42.850 --> 01:03:44.840
extends a little bit
farther than the body.

01:03:44.840 --> 01:03:48.490
We don't want to create a box
collider for the entire helicopter,

01:03:48.490 --> 01:03:52.220
because a box collider right
that goes out here, for example,

01:03:52.220 --> 01:03:54.460
might not be super fair
if we're just coming right

01:03:54.460 --> 01:03:56.515
over a building, and our body--

01:03:59.080 --> 01:04:01.740
maybe the building's right
here, and we just miss it.

01:04:01.740 --> 01:04:03.500
We don't want that to be collided with.

01:04:03.500 --> 01:04:05.590
So sometimes you'll need
to combine colliders

01:04:05.590 --> 01:04:09.112
to accomplish the collision
detection behavior you're looking at.

01:04:09.112 --> 01:04:11.570
The nice thing about box
colliders, which we're using here,

01:04:11.570 --> 01:04:14.194
is that they're not very expensive,
because they're just boxes.

01:04:14.194 --> 01:04:19.340
It's easy to compute 3D box collision
with other things that are 3D boxes.

01:04:19.340 --> 01:04:23.320
And that's actually a
topic in its own is,

01:04:23.320 --> 01:04:27.520
taking a complicated model or
object, and then breaking it down,

01:04:27.520 --> 01:04:29.920
not in terms of what it looks
like to be collided with,

01:04:29.920 --> 01:04:32.890
but how you can simplify the
collision detection of something,

01:04:32.890 --> 01:04:38.320
like a character, by just modeling its
arms, its body, its legs, as cylinders

01:04:38.320 --> 01:04:42.100
or boxes, rather than
complicated geometry.

01:04:42.100 --> 01:04:45.850
You usually don't want to do peer
geometry collision for anything,

01:04:45.850 --> 01:04:48.130
because that gets really expensive.

01:04:48.130 --> 01:04:52.510
You want to try and aim for simple
shapes to be your colliders.

01:04:52.510 --> 01:04:54.370
And Unity gives you a
lot of simple shapes

01:04:54.370 --> 01:04:59.212
by default. If you look at, for
example, in our helicopter--

01:04:59.212 --> 01:05:01.420
if you wanted to add a
component-- which, by the way,

01:05:01.420 --> 01:05:05.170
you can easily do here, just
in the component inspector.

01:05:05.170 --> 01:05:08.290
If you're looking at the bottom right,
there's an Add Component button.

01:05:08.290 --> 01:05:12.020
So you can add any of the
components that you've written,

01:05:12.020 --> 01:05:15.050
and also all the components
that Unity gives you by default.

01:05:15.050 --> 01:05:16.851
So if we look at it by
collider, we can see

01:05:16.851 --> 01:05:19.600
there's a lot of different colliders
that Unity gives us for free.

01:05:19.600 --> 01:05:25.810
Polygon collider, mesh collider,
box collider, capsule collider.

01:05:25.810 --> 01:05:28.540
I try and strive for
boxes as much as I can.

01:05:28.540 --> 01:05:29.470
Spheres aren't bad.

01:05:29.470 --> 01:05:31.750
Spheres are usually fairly
easy to calculate, as well.

01:05:31.750 --> 01:05:33.730
But boxes are the easiest.

01:05:33.730 --> 01:05:35.770
Capsules are pretty easy, too.

01:05:35.770 --> 01:05:39.220
A lot of players will be capsule
colliders, because characters usually

01:05:39.220 --> 01:05:40.270
have rounded heads.

01:05:40.270 --> 01:05:45.142
So emulating the collision for their
head with a capsule makes more sense.

01:05:45.142 --> 01:05:48.100
And we'll look at that, actually,
next week, when we use a first-person

01:05:48.100 --> 01:05:49.810
component that we can get for free.

01:05:49.810 --> 01:05:55.180
The default collider
for it is a capsule.

01:05:55.180 --> 01:06:02.950
But the blades and the body
both have their own collider.

01:06:02.950 --> 01:06:04.360
They're not triggers.

01:06:04.360 --> 01:06:08.050
But if we look at our prefabs--

01:06:08.050 --> 01:06:10.900
which we'll take a look at
what a prefab is shortly--

01:06:10.900 --> 01:06:16.240
a skyscraper has a box collider which
is a trigger, as we can see here.

01:06:16.240 --> 01:06:18.340
And the coin is a trigger.

01:06:18.340 --> 01:06:20.710
And the airplane is a trigger.

01:06:20.710 --> 01:06:27.800
So these things all trigger, except
other colliders that aren't triggers.

01:06:27.800 --> 01:06:30.940
And if it detects a collision with
a collider that's not a trigger,

01:06:30.940 --> 01:06:33.923
it will call the
OnTriggerEnter function,

01:06:33.923 --> 01:06:36.506
which we saw is something that
you can get with MonoBehaviour.

01:06:36.506 --> 01:06:37.438
Yeah.

01:06:37.438 --> 01:06:41.163
AUDIENCE: Could you have two values
if you want to call the special

01:06:41.163 --> 01:06:44.931
function two at the same time,
you'd have the regular [INAUDIBLE]..

01:06:44.931 --> 01:06:47.456
Is there an easier way to do that?

01:06:47.456 --> 01:06:49.497
COLTON OGDEN: Can you give
me a specific example?

01:06:49.497 --> 01:06:53.473
AUDIENCE: Well, if I want to
have a pinball game or something,

01:06:53.473 --> 01:06:58.443
I'd want to model functioning
when my ball hits something.

01:06:58.443 --> 01:07:01.440
But at the same time, I just
don't it to bounce off of stuff.

01:07:01.440 --> 01:07:02.398
COLTON OGDEN: Oh, yeah.

01:07:02.398 --> 01:07:03.910
AUDIENCE: So you could do that?

01:07:03.910 --> 01:07:09.674
COLTON OGDEN: So the question was, can
I implement such that, for example,

01:07:09.674 --> 01:07:12.340
in a pinball game, if I have a
ball that collides with something

01:07:12.340 --> 01:07:15.994
and causes a trigger to occur, but
also have it bounce off of something.

01:07:15.994 --> 01:07:17.660
And you would do that with a rigid body.

01:07:17.660 --> 01:07:19.330
So you give it a rigid body.

01:07:19.330 --> 01:07:23.110
In this case, I actually gave
a rigid body to the helicopter

01:07:23.110 --> 01:07:26.699
because the original goal of mine was
to have it be affected by gravity.

01:07:26.699 --> 01:07:29.990
But it turned out that I actually liked
it a little bit better without gravity.

01:07:29.990 --> 01:07:32.200
So this rigid body isn't
strictly necessary.

01:07:32.200 --> 01:07:34.720
But it has a gravity
component that you can

01:07:34.720 --> 01:07:39.640
assign to it that will actually,
then, calculate gravity, and pull it

01:07:39.640 --> 01:07:44.350
down wherever-- you have a
global gravity definition that's

01:07:44.350 --> 01:07:47.810
in your Unity settings that
will affect it that way.

01:07:47.810 --> 01:07:51.066
And so what you would do is, you
would give your ball a rigid body.

01:07:51.066 --> 01:07:53.440
And other things that you want
it to bounce off of those,

01:07:53.440 --> 01:07:55.450
those also have rigid bodies.

01:07:55.450 --> 01:07:59.532
And they can be kinematic
or not, basically,

01:07:59.532 --> 01:08:00.740
which we talked about before.

01:08:00.740 --> 01:08:05.990
Kinematic can move, but not
be affected by other objects.

01:08:05.990 --> 01:08:10.495
And so the object that's a trigger, you
still trigger code, it does something.

01:08:10.495 --> 01:08:12.870
So your pinball machine, when
it collides with something,

01:08:12.870 --> 01:08:17.054
and it triggers that thing,
it'll still trigger that code.

01:08:17.054 --> 01:08:19.470
So whether that's increment
your score, or cause something

01:08:19.470 --> 01:08:22.259
to flash, a part of it will
flash, or play a sound,

01:08:22.259 --> 01:08:23.800
it'll do that in your OnTriggerEnter.

01:08:23.800 --> 01:08:26.640
But your rigid body will
also perform its work,

01:08:26.640 --> 01:08:28.890
and bounce off of whatever it--

01:08:28.890 --> 01:08:32.729
assuming that you don't destroy it
with that OnTriggerEnter function,

01:08:32.729 --> 01:08:35.520
it will bounce off of that
surface, and behave in the way

01:08:35.520 --> 01:08:37.450
that you are alluding to.

01:08:37.450 --> 01:08:40.130
Does that make sense?

01:08:40.130 --> 01:08:41.298
All right.

01:08:41.298 --> 01:08:41.798
Cool.

01:08:44.810 --> 01:08:47.540
So all these things have triggers.

01:08:47.540 --> 01:08:49.719
The IsTrigger flag--

01:08:49.719 --> 01:08:51.510
I mean, that's as easy
as we need it to be.

01:08:51.510 --> 01:08:52.939
So you just give a box collider.

01:08:52.939 --> 01:08:54.950
And the nice thing
about box collider, too,

01:08:54.950 --> 01:09:00.020
is if your mesh is a box,
or square, or rectangular,

01:09:00.020 --> 01:09:04.686
it will usually just fit it perfectly to
whatever you're trying to assign it to.

01:09:04.686 --> 01:09:07.810
So in this case, I remember adding the
box colliders for these skyscrapers.

01:09:07.810 --> 01:09:12.050
It just-- because they're
all rectangular, or cubical--

01:09:12.050 --> 01:09:12.649
I don't know.

01:09:12.649 --> 01:09:14.060
What's the rectangular 3D?

01:09:14.060 --> 01:09:15.780
I forget the term.

01:09:15.780 --> 01:09:16.279
What is it?

01:09:16.279 --> 01:09:17.479
AUDIENCE: Rectangular prism.

01:09:17.479 --> 01:09:19.020
COLTON OGDEN: Rectangular prism, yes.

01:09:19.020 --> 01:09:23.000
Because they're all rectangular
prisms, the box collector fits them.

01:09:23.000 --> 01:09:25.310
It'll scale the right way.

01:09:25.310 --> 01:09:27.950
When you have differently
weird shaped objects,

01:09:27.950 --> 01:09:30.229
it'll just basically
be as big as it needs

01:09:30.229 --> 01:09:32.960
to be to completely encapsulate it.

01:09:32.960 --> 01:09:37.460
But like I said before, because the
helicopter has got some weird geometry,

01:09:37.460 --> 01:09:41.090
if we were to do that, it would by
default just be this entire box here,

01:09:41.090 --> 01:09:45.470
because this is the farthest it
goes out on this particular axis.

01:09:45.470 --> 01:09:50.870
So we want to combine meshes
to produce the collision

01:09:50.870 --> 01:09:52.310
behavior that we're looking for.

01:09:52.310 --> 01:10:02.090
And the trigger enter bit is relevant
because, if your game object is

01:10:02.090 --> 01:10:09.560
a trigger, then once we
collide with that object,

01:10:09.560 --> 01:10:11.920
we want-- and by default,
when you do OnTriggerEnter,

01:10:11.920 --> 01:10:15.830
it will look for the
collider on this object.

01:10:15.830 --> 01:10:18.630
It's going to take in a
collider other, right?

01:10:18.630 --> 01:10:21.950
And what that is is the
other collider-- the thing

01:10:21.950 --> 01:10:24.650
that's colliding with this
object, with this coin.

01:10:24.650 --> 01:10:27.680
So the helicopter, because it's
the only other object in our scene

01:10:27.680 --> 01:10:31.267
that has a non-trigger collider.

01:10:31.267 --> 01:10:33.350
OnTriggerEnter-- this is
going to be a helicopter.

01:10:33.350 --> 01:10:38.480
We can just say other.transform.parent,
because our helicopter has children,

01:10:38.480 --> 01:10:42.200
which have the actual colliders, and
a parent has the helicopter controller

01:10:42.200 --> 01:10:43.060
component.

01:10:43.060 --> 01:10:47.460
We're going to GetComponent
the HeliController.

01:10:47.460 --> 01:10:50.254
So we're going to go through
our that objects, that other

01:10:50.254 --> 01:10:51.170
that collided with us.

01:10:51.170 --> 01:10:54.182
We're going to get its transform parent.

01:10:54.182 --> 01:10:57.140
We're going to do GetComponent, which
is a function that will just look

01:10:57.140 --> 01:10:59.360
through all of its list of components.

01:10:59.360 --> 01:11:03.770
We specify which component we
want using this identifier here.

01:11:03.770 --> 01:11:06.050
So of class HeliController.

01:11:06.050 --> 01:11:16.130
And these angle brackets are
the generic type specifier

01:11:16.130 --> 01:11:17.930
syntax, which basically looks for it.

01:11:17.930 --> 01:11:20.780
You could pass in any
type here, effectively,

01:11:20.780 --> 01:11:23.210
and GetComponent will look
at whatever type is in here,

01:11:23.210 --> 01:11:25.850
and get the component of
that type, specifically.

01:11:25.850 --> 01:11:29.750
So you do have some sort
of type flexibility in C#,

01:11:29.750 --> 01:11:32.330
but you have to go the
extra mile and specify it,

01:11:32.330 --> 01:11:35.840
and implement functions that
take generic arguments like this.

01:11:35.840 --> 01:11:41.430
Which is similar to Java, and C++, and
other languages that do it that way.

01:11:41.430 --> 01:11:45.590
And then once we've gotten that
component of type HeliController,

01:11:45.590 --> 01:11:50.010
with this function call,
we execute PickupCoin,

01:11:50.010 --> 01:11:53.390
which is a function that's
part of the HeliController.

01:11:53.390 --> 01:11:55.110
Any guesses as to what PickupCoin does?

01:11:59.574 --> 01:12:00.570
AUDIENCE: [INAUDIBLE]

01:12:00.570 --> 01:12:01.278
COLTON OGDEN: Sorry?

01:12:01.278 --> 01:12:04.180
AUDIENCE: Increments the coin counter
and tells the coin to disappear.

01:12:04.180 --> 01:12:06.470
COLTON OGDEN: Increments the coin
counter, calls the coin to disappear.

01:12:06.470 --> 01:12:09.910
Well, it actually doesn't call the coin
to disappear, because we do that here.

01:12:09.910 --> 01:12:10.710
AUDIENCE: Oh.

01:12:10.710 --> 01:12:13.510
COLTON OGDEN: Destroy game object--

01:12:13.510 --> 01:12:17.284
game object is going to be this
coin that's executing this function.

01:12:17.284 --> 01:12:18.450
There's one more thing, too.

01:12:18.450 --> 01:12:21.120
Do you remember what happens
when we pick up a coin?

01:12:21.120 --> 01:12:21.620
Exactly.

01:12:21.620 --> 01:12:22.280
The particle effect.

01:12:22.280 --> 01:12:23.530
It triggers a particle effect.

01:12:23.530 --> 01:12:28.060
We can go to the HeliController
class and take a look at that.

01:12:28.060 --> 01:12:28.840
PickupCoin.

01:12:31.540 --> 01:12:33.730
Here, coinTotal plus equals 1.

01:12:33.730 --> 01:12:37.851
GetComponent AudioSource.

01:12:37.851 --> 01:12:38.350
Play.

01:12:38.350 --> 01:12:39.860
So it's a little bit weird.

01:12:39.860 --> 01:12:44.150
So with audio source, you can
have multiple audio files.

01:12:44.150 --> 01:12:48.160
So GetComponents AudioSource
is what we need to actually get

01:12:48.160 --> 01:12:49.970
the audio attached to this object.

01:12:49.970 --> 01:12:51.400
And at index 0--

01:12:51.400 --> 01:12:54.400
because there's only going to
be one audio source anyway.

01:12:54.400 --> 01:12:58.510
And then we just call Play, so
that'll play the coin sound.

01:12:58.510 --> 01:13:00.430
And then GetComponent,
because there's only

01:13:00.430 --> 01:13:04.944
going to be one particle system
associated with this helicopter object.

01:13:04.944 --> 01:13:06.860
We're going to get the
particle system object.

01:13:06.860 --> 01:13:09.985
And then we're just going to call Play
on that, which will actually trigger

01:13:09.985 --> 01:13:14.830
an emission one time of its particles.

01:13:14.830 --> 01:13:18.100
That's in a nutshell what
colliders and triggers are.

01:13:18.100 --> 01:13:22.780
It's a lot of syntax at once,
because Unity is really big.

01:13:22.780 --> 01:13:25.030
But it's pretty simple.

01:13:25.030 --> 01:13:27.940
Just make sure that you give the
right shapes to your objects.

01:13:27.940 --> 01:13:29.950
Make the right things
triggers that you want

01:13:29.950 --> 01:13:34.930
to cause behavior to happen when
non-trigger things touch them.

01:13:34.930 --> 01:13:38.440
And then implement OnTriggerEnter
with the behavior-- the game logic--

01:13:38.440 --> 01:13:39.880
that you need.

01:13:39.880 --> 01:13:43.270
In the case of the skyscraper, for
example, if we look at the skyscraper.

01:13:43.270 --> 01:13:45.890
So I have a skyscraper component here.

01:13:45.890 --> 01:13:49.990
And then if I OnTriggerEnter
here, it effectively

01:13:49.990 --> 01:13:53.890
does the same thing
that the airplane does,

01:13:53.890 --> 01:14:00.500
which is just go through the others,
transform parent game object,

01:14:00.500 --> 01:14:03.350
HeliController, and then call Explode.

01:14:03.350 --> 01:14:06.890
And so Explode-- similar
thing to what PickupCoin does,

01:14:06.890 --> 01:14:08.950
and it triggers a particle effect.

01:14:08.950 --> 01:14:14.200
But it also destroys the helicopter,
and it tweaks the Game Over text

01:14:14.200 --> 01:14:16.850
to turn on at that point.

01:14:16.850 --> 01:14:20.794
So any questions as to how triggers
work, or any of the syntax we've

01:14:20.794 --> 01:14:21.710
talked about thus far?

01:14:21.710 --> 01:14:24.010
I know that it's a lot.

01:14:24.010 --> 01:14:25.330
It's kind of a fast tour.

01:14:25.330 --> 01:14:30.130
But moving right along.

01:14:30.130 --> 01:14:30.910
All right.

01:14:30.910 --> 01:14:34.240
Oh, and here's a screenshot I took
just to illustrate the green lines--

01:14:34.240 --> 01:14:40.690
the box-- and then the orange is
the actual mesh of the helicopter.

01:14:40.690 --> 01:14:41.975
So we're going take a break.

01:14:41.975 --> 01:14:44.350
And then when we get back,
we're gonna talk about prefabs

01:14:44.350 --> 01:14:47.350
and spawning them, and
dive a little bit deeper

01:14:47.350 --> 01:14:49.821
into some of the other
parts of the project.

01:14:49.821 --> 01:14:50.320
All right.

01:14:50.320 --> 01:14:52.090
Welcome back to GD50 Lecture 8.

01:14:52.090 --> 01:14:53.560
This is Helicopter Game 3D.

01:14:53.560 --> 01:14:57.130
So before the break, we were talking
about colliders and triggers,

01:14:57.130 --> 01:15:01.930
and also just getting our hands used to
using MonoBehaviours, and the editor,

01:15:01.930 --> 01:15:03.610
and all sorts of things.

01:15:03.610 --> 01:15:05.680
But we haven't really
taken a look at prefabs,

01:15:05.680 --> 01:15:08.260
which is a major part of this game.

01:15:08.260 --> 01:15:12.040
So the coins, the
skyscrapers, the airplanes--

01:15:12.040 --> 01:15:16.810
those are all prefabricated
assets that we have gotten

01:15:16.810 --> 01:15:19.670
ready for spawning into our scene.

01:15:19.670 --> 01:15:22.730
And we're going to take a look
at how that actually works.

01:15:22.730 --> 01:15:24.670
So here's a list of--

01:15:24.670 --> 01:15:27.310
in our editor view-- all the
different prefabs that we have.

01:15:27.310 --> 01:15:31.960
So we can see airplane,
blades, and body are prefabs.

01:15:31.960 --> 01:15:33.812
The coin, all the skyscrapers.

01:15:33.812 --> 01:15:35.770
There are three different
kinds of skyscrapers.

01:15:35.770 --> 01:15:37.227
And then the helicopter.

01:15:37.227 --> 01:15:39.310
The helicopter itself we're
not using as a prefab,

01:15:39.310 --> 01:15:40.870
because I've already
created it in the scene,

01:15:40.870 --> 01:15:42.670
and it never gets
instantiated dynamically.

01:15:42.670 --> 01:15:45.910
But we could easily make
it so, because I have

01:15:45.910 --> 01:15:49.990
created a prefab with the helicopter.

01:15:49.990 --> 01:15:53.290
So when we're looking
at the scene here, we

01:15:53.290 --> 01:15:57.350
notice that we have just the
helicopter, and we have the background.

01:15:57.350 --> 01:16:01.790
But there's no skyscrapers, there's
no coins, and there's no airplanes.

01:16:01.790 --> 01:16:07.170
Well, we do have our skyscraper spawner,
the coin spawner, and the airplane

01:16:07.170 --> 01:16:07.840
spawner.

01:16:07.840 --> 01:16:10.570
And the three of those are
just empty game objects,

01:16:10.570 --> 01:16:13.450
but they have associated with
them these spawner scripts.

01:16:13.450 --> 01:16:16.120
And the spawner scripts,
we've written ourself.

01:16:16.120 --> 01:16:19.580
And then, once we've written them,
we just simply add component here,

01:16:19.580 --> 01:16:22.450
and then chosen the appropriate spawner.

01:16:22.450 --> 01:16:24.040
And so what those do--

01:16:24.040 --> 01:16:28.450
if we look in our code actually, and
we go, for example, to the airplane

01:16:28.450 --> 01:16:33.520
spawner, we have a Start method.

01:16:33.520 --> 01:16:34.610
We have an Update method.

01:16:34.610 --> 01:16:38.140
Notice that the Update method
doesn't do anything, paradoxically,

01:16:38.140 --> 01:16:42.040
because the airplane spawner
is running over time.

01:16:42.040 --> 01:16:45.100
We are spawning airplanes over time.

01:16:45.100 --> 01:16:48.430
But the way that we do things
over time asynchronously in Unity

01:16:48.430 --> 01:16:51.470
is a little bit different than
anything that we've done so far.

01:16:51.470 --> 01:16:54.910
So this Start method here,
we see that we're calling

01:16:54.910 --> 01:16:57.400
this function called StartCoroutine.

01:16:57.400 --> 01:17:01.330
And that function takes in a
function called SpawnAirplanes.

01:17:01.330 --> 01:17:06.460
And so at a high level, a
coroutine is effectively a function

01:17:06.460 --> 01:17:09.850
that yields control
every time it's called.

01:17:09.850 --> 01:17:15.310
So it'll run, and then, rather than
go through its entire body of code,

01:17:15.310 --> 01:17:19.180
and then end or return some value,
and have that just be the end of it,

01:17:19.180 --> 01:17:25.720
it'll actually yield, when
you use the keyword Yield.

01:17:25.720 --> 01:17:30.160
And depending on what
you've done with that Yield,

01:17:30.160 --> 01:17:34.660
it'll pause for some length of time, or
do something for some length of time,

01:17:34.660 --> 01:17:37.130
rather than end that function call.

01:17:37.130 --> 01:17:39.310
So this SpawnAirplanes function here--

01:17:39.310 --> 01:17:41.770
notice that it has a while true.

01:17:41.770 --> 01:17:45.550
And so while true is not usually
something that you want in a game,

01:17:45.550 --> 01:17:49.480
because that's just going
to lock your game forever.

01:17:49.480 --> 01:17:54.760
But in the case of a coroutine,
a coroutine is going to run,

01:17:54.760 --> 01:17:56.680
but then it's going
to yield control back

01:17:56.680 --> 01:17:58.600
to whatever called it
for some length of time,

01:17:58.600 --> 01:18:00.940
or depending on how we've programmed it.

01:18:00.940 --> 01:18:02.500
In this case, you can see here--

01:18:02.500 --> 01:18:07.270
yield return new WaitForSeconds
Random.Range 3, 10.

01:18:07.270 --> 01:18:10.270
Does anybody have an
idea of what that does?

01:18:10.270 --> 01:18:10.770
Yeah.

01:18:10.770 --> 01:18:15.650
AUDIENCE: The logic [INAUDIBLE]
waits for between 3 and 10 seconds,

01:18:15.650 --> 01:18:16.600
and continues.

01:18:16.600 --> 01:18:19.050
COLTON OGDEN: It does.

01:18:19.050 --> 01:18:22.660
It yields for 3 to 10 seconds,
and then continues its execution.

01:18:22.660 --> 01:18:23.605
That's exactly right.

01:18:23.605 --> 01:18:24.760
Did you have a question?

01:18:24.760 --> 01:18:27.984
AUDIENCE: I was thinking, why do you
have three different skyscrapers set

01:18:27.984 --> 01:18:28.484
up?

01:18:28.484 --> 01:18:32.177
Couldn't you just have one
skyscraper and change [INAUDIBLE]??

01:18:32.177 --> 01:18:33.510
COLTON OGDEN: You could do that.

01:18:33.510 --> 01:18:34.129
Yeah.

01:18:34.129 --> 01:18:36.045
I guess for the sake of
demonstrating prefabs.

01:18:36.045 --> 01:18:38.503
And also, it's a little bit
complex more complicated to get

01:18:38.503 --> 01:18:42.981
into dynamic material setting,
and changing materials in code.

01:18:42.981 --> 01:18:43.480
But yeah.

01:18:43.480 --> 01:18:50.230
You could effectively just create
one skyscraper with one base color,

01:18:50.230 --> 01:18:56.570
and then dynamically
change its material.

01:18:56.570 --> 01:18:59.885
But also to illustrate having
multiple different prefabs

01:18:59.885 --> 01:19:02.260
assigned to an object, that
you can then choose at random

01:19:02.260 --> 01:19:03.510
to generate in the game scene.

01:19:03.510 --> 01:19:05.600
They might not
necessarily be skyscrapers

01:19:05.600 --> 01:19:07.100
that will have the exact same color.

01:19:07.100 --> 01:19:12.770
It could be a goblin, or a
orc, or a troll, or something.

01:19:12.770 --> 01:19:15.290
And they're all different
prefabs that we've created.

01:19:15.290 --> 01:19:18.220
But you can put them in a list,
and then dynamically choose

01:19:18.220 --> 01:19:20.305
which one we want at random.

01:19:20.305 --> 01:19:21.430
So a few different reasons.

01:19:21.430 --> 01:19:21.929
But yeah.

01:19:21.929 --> 01:19:25.027
In a situation where everything
is just effectively differentiated

01:19:25.027 --> 01:19:26.860
by a single color and
a material change, you

01:19:26.860 --> 01:19:29.020
could dynamically swap that as needed.

01:19:33.610 --> 01:19:36.730
This code routine that we've
started-- this function that

01:19:36.730 --> 01:19:42.400
effectively can pause itself, even
though it's being called while true

01:19:42.400 --> 01:19:45.170
is in play.

01:19:45.170 --> 01:19:47.290
It yields control with
this Yield keyword.

01:19:47.290 --> 01:19:51.100
And what it does is, it allows us to
call something over and over again,

01:19:51.100 --> 01:19:53.300
but then pause for some length of time.

01:19:53.300 --> 01:19:53.800
Right?

01:19:53.800 --> 01:19:57.201
We don't have to maintain a
counter for spawn time in here.

01:19:57.201 --> 01:19:57.950
Which we could do.

01:19:57.950 --> 01:20:01.690
We could do float spawn
time equals 0, right?

01:20:01.690 --> 01:20:06.880
And then float spawn
increment equals like 1,000.

01:20:06.880 --> 01:20:13.000
And then while spawn time is
less than spawn increment--

01:20:13.000 --> 01:20:16.450
we could say in Update,
if spawn increment.

01:20:16.450 --> 01:20:20.389
Or we would do spawn time plus
equals time.delta time first,

01:20:20.389 --> 01:20:22.930
to get the length of time that's
passed since the last frame.

01:20:22.930 --> 01:20:26.170
And then we would say,
if spawn time is greater

01:20:26.170 --> 01:20:32.260
than spawn increment,
instantiate a new airplane.

01:20:32.260 --> 01:20:37.120
And then set spawn time back to 0.

01:20:37.120 --> 01:20:40.430
And then just rinse and repeat
this over and over again.

01:20:40.430 --> 01:20:44.470
But coroutines take out
this need, much like timer

01:20:44.470 --> 01:20:49.000
did, for having anything that you
keep track of with a specific timer.

01:20:49.000 --> 01:20:51.550
You can do a whole bunch of
different things with coroutines.

01:20:51.550 --> 01:20:53.341
One of them, in this
case that we're doing,

01:20:53.341 --> 01:20:57.850
is just pausing for some
length of time to do something.

01:20:57.850 --> 01:21:00.160
In this case, we want
to wait for some time

01:21:00.160 --> 01:21:07.000
in between each
instantiation of an airplane.

01:21:07.000 --> 01:21:10.850
So we'll just yield
control back to our game,

01:21:10.850 --> 01:21:12.850
because we want to break
out of this while true.

01:21:12.850 --> 01:21:16.141
But we don't want to break out of it and
completely break out of this function.

01:21:16.141 --> 01:21:19.930
We want this to keep
going over and over again.

01:21:19.930 --> 01:21:23.500
So we see here, this
Instantiate function is

01:21:23.500 --> 01:21:25.540
where the actual instantiation happens.

01:21:25.540 --> 01:21:29.500
And Instantiate takes in a prefab--

01:21:29.500 --> 01:21:30.900
so a game object.

01:21:30.900 --> 01:21:35.350
So in this case, we have
a prefabs list here.

01:21:35.350 --> 01:21:39.259
GameObject public, GameObject
array called prefabs.

01:21:39.259 --> 01:21:41.800
So this can take in any number
of prefabs that we want it to.

01:21:44.380 --> 01:21:48.700
We're going to return a
range between 0 and length.

01:21:48.700 --> 01:21:52.992
And then also, we want it to spawn.

01:21:52.992 --> 01:21:54.950
We give it a position
that we want to spawn in.

01:21:54.950 --> 01:21:58.480
So Instantiate-- it takes in an
object, it takes in a position,

01:21:58.480 --> 01:21:59.890
and it takes in a rotation.

01:21:59.890 --> 01:22:02.710
In this case, we want to
give it this position.

01:22:02.710 --> 01:22:03.840
So it's a Vector3--

01:22:03.840 --> 01:22:05.740
it's an x, y, and a z--

01:22:05.740 --> 01:22:06.460
at 26.

01:22:06.460 --> 01:22:09.580
So off the right edge
of the screen 7 to 10.

01:22:09.580 --> 01:22:14.140
So within a range of
verticality up towards the top.

01:22:14.140 --> 01:22:17.920
And then at 11 on the z-axis, which
is aligned with our helicopter

01:22:17.920 --> 01:22:21.280
and the skyscrapers.

01:22:21.280 --> 01:22:25.300
And then this Quaternion.Euler--

01:22:25.300 --> 01:22:30.230
so 3D rotation, the math
behind it is pretty complex.

01:22:30.230 --> 01:22:32.000
And I don't know it well at all.

01:22:32.000 --> 01:22:35.700
But Quaternion.Euler allows
us to think in degrees,

01:22:35.700 --> 01:22:40.130
and actually perform a 3D rotation
on something fairly easily.

01:22:40.130 --> 01:22:43.540
So if you want to rotate
something in 3D, Quaternion.Euler.

01:22:43.540 --> 01:22:46.980
Negative 90 degrees on the,
I believe it's z, x, y.

01:22:46.980 --> 01:22:50.860
In this case, the way that the
default rotation of the airplane is,

01:22:50.860 --> 01:22:54.070
we want to set it to
negative 90, negative 90, 0.

01:22:54.070 --> 01:22:58.180
You could also set up
your prefab in a way such

01:22:58.180 --> 01:23:00.550
that you don't need to pass this in.

01:23:00.550 --> 01:23:03.420
You could do Quaternion.Identity
in that case.

01:23:03.420 --> 01:23:06.632
But this is just to illustrate how,
if you want to rotate something

01:23:06.632 --> 01:23:07.840
in code, how you would do it.

01:23:07.840 --> 01:23:10.720
So Quaternion.Euler is the way
that you rotate something in 3D.

01:23:13.660 --> 01:23:15.957
So Instantiate-- global
function that you

01:23:15.957 --> 01:23:18.040
can call anywhere you want
to, as long as you just

01:23:18.040 --> 01:23:23.560
give it a actual object or prefab
that it knows how to instantiate.

01:23:23.560 --> 01:23:25.700
And then WaitForSeconds--
another global object,

01:23:25.700 --> 01:23:28.120
which is a asynchronous
object that will allow

01:23:28.120 --> 01:23:31.630
us to yield for this length of time.

01:23:31.630 --> 01:23:33.302
You pass in the length of time here.

01:23:33.302 --> 01:23:35.260
It takes it in seconds,
because WaitForSeconds.

01:23:35.260 --> 01:23:39.610
And then, as soon as this
length of time has passed,

01:23:39.610 --> 01:23:42.910
it's going to come back up here
into this while true instruction,

01:23:42.910 --> 01:23:44.290
and then instantiate again.

01:23:44.290 --> 01:23:47.950
We don't have to keep track of a time
or anything-- any weird boilerplate.

01:23:47.950 --> 01:23:51.290
We just have to call
StartCoroutine here.

01:23:51.290 --> 01:23:54.640
And notice that we explicitly have to
call StartCoroutine routine in order

01:23:54.640 --> 01:23:58.760
to trigger a coroutine function.

01:23:58.760 --> 01:24:02.410
And to do that, it returns
what's called an IEnumerator.

01:24:02.410 --> 01:24:05.570
And so a lot of these details,
you don't need to necessarily know

01:24:05.570 --> 01:24:06.760
the low-level details of.

01:24:06.760 --> 01:24:10.120
I certainly don't know all the
low-level details of everything

01:24:10.120 --> 01:24:11.560
that happens in Unity.

01:24:11.560 --> 01:24:13.810
But just know if you want
asynchronous behavior,

01:24:13.810 --> 01:24:15.730
your function needs to
return an IEnumerator,

01:24:15.730 --> 01:24:22.750
which C# knows is a generator
function which will yield control

01:24:22.750 --> 01:24:24.910
at predetermined times.

01:24:24.910 --> 01:24:27.250
And it will manage it for you.

01:24:27.250 --> 01:24:29.590
And to trigger it, you
need to StartCoroutine,

01:24:29.590 --> 01:24:33.280
which is a function that
Unity has defined for you.

01:24:33.280 --> 01:24:38.555
So any questions as to how this
works at a high level, at least?

01:24:38.555 --> 01:24:40.888
AUDIENCE: I'm a little confused
on the syntax for Yield.

01:24:40.888 --> 01:24:42.390
Does the Yield return--

01:24:42.390 --> 01:24:44.680
COLTON OGDEN: Yes.

01:24:44.680 --> 01:24:51.670
Yield takes in something, and you get a
new to instantiate a new WaitForSecond.

01:24:51.670 --> 01:24:56.451
It's just the way the syntax
is for yielding an object.

01:24:56.451 --> 01:24:56.950
Yield--

01:24:56.950 --> 01:24:58.482
AUDIENCE: What is it returning back?

01:24:58.482 --> 01:25:00.940
COLTON OGDEN: It's returning
this to the Yield instruction.

01:25:00.940 --> 01:25:05.260
And the Yield instruction
is then yielding that.

01:25:05.260 --> 01:25:06.980
It is a little bit weird, though.

01:25:06.980 --> 01:25:09.970
But you only really have to--

01:25:09.970 --> 01:25:11.900
this is a common
pattern that you'll see.

01:25:11.900 --> 01:25:13.316
And so you'll just get used to it.

01:25:16.360 --> 01:25:20.080
And honestly, this is probably one of
the more syntactically difficult things

01:25:20.080 --> 01:25:20.600
about Unity.

01:25:20.600 --> 01:25:22.349
So I mean, as soon as
you understand this,

01:25:22.349 --> 01:25:25.840
pretty much anything else is
fairly easy at that point.

01:25:25.840 --> 01:25:28.930
I would say this is one
of the weirder sides.

01:25:28.930 --> 01:25:32.680
Because in Lua, and Love2D, and
those kinds of environments,

01:25:32.680 --> 01:25:37.540
it's a little bit easier to do this
sort of thing with as much syntax.

01:25:37.540 --> 01:25:42.400
C#, being a statically-typed
environment, to get the same behavior,

01:25:42.400 --> 01:25:46.290
you have to go a little bit further.

01:25:46.290 --> 01:25:48.460
Do things their way.

01:25:48.460 --> 01:25:54.190
But that's getting asynchronous
behavior to work in C#.

01:25:54.190 --> 01:26:01.290
And in Unity, typically, in order
to avoid messy state management,

01:26:01.290 --> 01:26:06.790
you will use coroutines,
which are IEnumerators, often

01:26:06.790 --> 01:26:09.910
with the WaitForSeconds object.

01:26:09.910 --> 01:26:14.290
And just make sure to trigger
them with StartCoroutine.

01:26:14.290 --> 01:26:17.115
And then call that function
as if it were an object.

01:26:17.115 --> 01:26:17.740
Just like that.

01:26:20.710 --> 01:26:25.960
And the behavior for the airplane
spawner, the coin spawner,

01:26:25.960 --> 01:26:27.950
and so forth, they're
all fairly similar.

01:26:27.950 --> 01:26:31.330
So StartCoroutine SpawnCoins.

01:26:31.330 --> 01:26:32.560
And then while true.

01:26:32.560 --> 01:26:36.670
So coins-- this row just spawns a
random number of coins vertically.

01:26:36.670 --> 01:26:40.387
So you can have one, or you
can maybe have a couple.

01:26:40.387 --> 01:26:42.220
And then for each of
those, instantiate them

01:26:42.220 --> 01:26:46.330
at a random position on the y-axis.

01:26:46.330 --> 01:26:49.180
Here, random negative 10 to 10.

01:26:49.180 --> 01:26:52.540
In this case, Quaternion.Identity,
because we don't want

01:26:52.540 --> 01:26:58.250
to rotate them any differently than they
already are, which I alluded to before.

01:26:58.250 --> 01:27:01.350
So Quaternion.Identity just means
no rotation applied to the object.

01:27:01.350 --> 01:27:05.510
So whatever its base
rotation is as a prefab.

01:27:05.510 --> 01:27:08.000
So it'll be whatever it is
when you see it in the editor,

01:27:08.000 --> 01:27:12.270
and when you create a new one, that's
going to be its default rotation.

01:27:12.270 --> 01:27:15.230
So basically the equivalent of,
don't rotate this by anything.

01:27:18.200 --> 01:27:25.400
And then, same as we saw before,
yields a new WaitForSeconds.

01:27:25.400 --> 01:27:29.660
In this case, 1 to 5, so a little bit
more frequently than the airplane,

01:27:29.660 --> 01:27:30.230
on average.

01:27:30.230 --> 01:27:31.870
More coins.

01:27:31.870 --> 01:27:37.580
As the airplane, I believe, was 3
to 10, so every 3 to 10 seconds.

01:27:37.580 --> 01:27:39.920
And that's basically that.

01:27:39.920 --> 01:27:44.660
And then we StartCoroutine, just like
we did before with the airplane spawner.

01:27:44.660 --> 01:27:47.330
And then lastly, the skyscraper spawner.

01:27:47.330 --> 01:27:52.690
In this case, we only
have one coin prefab,

01:27:52.690 --> 01:27:57.230
we only have one airplane prefab,
but we have three skyscraper prefabs.

01:27:57.230 --> 01:28:01.070
And so the actual Random.Range
here comes into play,

01:28:01.070 --> 01:28:05.010
because that's how we get the different
color skyscrapers spawning at random.

01:28:05.010 --> 01:28:07.100
And like I said before,
this can be extrapolated

01:28:07.100 --> 01:28:09.016
to whatever sort of game
environment you want,

01:28:09.016 --> 01:28:11.120
where you have multiple
types of objects that

01:28:11.120 --> 01:28:13.220
are more complicated
than just a color swap,

01:28:13.220 --> 01:28:17.180
and you want to choose them at random.

01:28:17.180 --> 01:28:20.000
We're doing all the same
things that we did before.

01:28:20.000 --> 01:28:25.850
And also, here, we can see
that they have a random chance

01:28:25.850 --> 01:28:30.610
1 in 4, so a 25% chance
of increasing the speed.

01:28:30.610 --> 01:28:35.950
So skyscraper spawner actually has--
and this is relevant to the assignment--

01:28:35.950 --> 01:28:41.570
skyscraper spawner has a float called
speed here, which is, by default, 10.

01:28:41.570 --> 01:28:46.460
And this drives the scroll speed
of the skyscrapers, the coins,

01:28:46.460 --> 01:28:48.340
and the airplanes.

01:28:48.340 --> 01:28:53.388
And so when we call it static,
do we know what that means?

01:28:53.388 --> 01:28:53.888
Yeah?

01:28:53.888 --> 01:29:00.730
AUDIENCE: Well, it's the same for
all [INAUDIBLE] objects [INAUDIBLE]..

01:29:00.730 --> 01:29:01.500
COLTON OGDEN: Yes.

01:29:01.500 --> 01:29:07.290
So no matter how many
skyscraper spawners we create,

01:29:07.290 --> 01:29:10.410
they're all going to
share this field speed,

01:29:10.410 --> 01:29:13.590
and it's always going to be equal to
the same amount across all instances.

01:29:13.590 --> 01:29:15.660
So static means that
it's part of the class.

01:29:15.660 --> 01:29:18.090
It belongs to the
SkyscraperSpawner class.

01:29:18.090 --> 01:29:21.390
It does not belong to a
SkyscraperSpawner object.

01:29:21.390 --> 01:29:26.340
And so we don't ever really want to
change that ourselves in this game.

01:29:26.340 --> 01:29:32.740
But the airplane, for example,
notice that in our Update function

01:29:32.740 --> 01:29:37.360
here, if the transform.position.x
is less than negative 25,

01:29:37.360 --> 01:29:38.740
we should destroy the airplane.

01:29:38.740 --> 01:29:41.180
So when it goes off screen,
we should destroy it.

01:29:41.180 --> 01:29:47.110
But if not, then we want
to translate this object

01:29:47.110 --> 01:29:52.780
on the x-axis by negative
SkyscraperSpawner.speed times 2 times

01:29:52.780 --> 01:29:54.610
Time.deltaTime.

01:29:54.610 --> 01:29:57.040
So we're translating it
on the x-axis, and we're

01:29:57.040 --> 01:30:00.940
using the SkyscraperSpawner.speed
as our core multiplier.

01:30:00.940 --> 01:30:03.850
And then if we look at coin--

01:30:03.850 --> 01:30:04.480
same thing.

01:30:08.740 --> 01:30:11.350
I should ask, what is
one design consideration

01:30:11.350 --> 01:30:12.610
if we're looking at this--

01:30:12.610 --> 01:30:13.840
all these components?

01:30:13.840 --> 01:30:17.380
And let's say we're trying
to get as decoupled as we

01:30:17.380 --> 01:30:19.580
can, and well-engineered as we can.

01:30:19.580 --> 01:30:23.110
What is a consideration that we
can, noticing that, for example,

01:30:23.110 --> 01:30:29.135
this exists in coin, and
this exists in airplane?

01:30:33.750 --> 01:30:35.250
AUDIENCE: What's the question again?

01:30:35.250 --> 01:30:37.374
COLTON OGDEN: So how could
we better engineer this?

01:30:37.374 --> 01:30:39.120
Notice that we have--

01:30:39.120 --> 01:30:43.290
and taking into consideration
this component model in Unity--

01:30:43.290 --> 01:30:45.738
what could we do with,
for example, this?

01:30:45.738 --> 01:30:50.420
AUDIENCE: So that Unity
better [INAUDIBLE]..

01:30:50.420 --> 01:30:53.640
COLTON OGDEN: Well, I'm thinking that,
because the airplane and the coin--

01:30:53.640 --> 01:30:55.890
well, first of all, it
wouldn't belong in the spawner,

01:30:55.890 --> 01:30:58.230
because the spawner's
job is to spawn coins.

01:30:58.230 --> 01:31:00.980
But the coins and the airplanes--
they have their behavior, right?

01:31:00.980 --> 01:31:03.320
They have their update behavior.

01:31:03.320 --> 01:31:06.800
But they're all doing kind of the same
thing, which is scrolling to the left,

01:31:06.800 --> 01:31:09.330
and then de-spawning at negative 25.

01:31:09.330 --> 01:31:13.940
So a design consideration here would
be, maybe we have a scroll component,

01:31:13.940 --> 01:31:15.395
right?

01:31:15.395 --> 01:31:17.300
Or a scroll and destroy component.

01:31:17.300 --> 01:31:20.697
Or just a scroll component
with an optional destroy flag.

01:31:20.697 --> 01:31:23.780
And then we just put this on anything
that we want to automatically scroll

01:31:23.780 --> 01:31:25.904
to the left screen and
de-spawn, rather than having

01:31:25.904 --> 01:31:28.530
to code this in every single class.

01:31:28.530 --> 01:31:30.800
So if you're ever looking
through your code,

01:31:30.800 --> 01:31:39.410
and you're seeing, for example, this and
this being the exact same, especially

01:31:39.410 --> 01:31:42.560
in Unity, because of how
flexible components are,

01:31:42.560 --> 01:31:46.340
try and think about how you can
make it into its own component.

01:31:46.340 --> 01:31:48.800
AUDIENCE: So where would you
put the coins [INAUDIBLE]??

01:31:48.800 --> 01:31:50.258
COLTON OGDEN: You make it yourself.

01:31:50.258 --> 01:31:53.210
So if we went into here, into
our Scripts thing, and just

01:31:53.210 --> 01:31:56.870
made a new script.

01:31:56.870 --> 01:31:59.600
And then we called it Scrollable.

01:31:59.600 --> 01:32:02.720
And then we double-click it,
it'll open up in our editor

01:32:02.720 --> 01:32:04.434
that we've chosen in our preferences.

01:32:04.434 --> 01:32:07.100
By default, it's going be Visual
Studio with the newer versions.

01:32:07.100 --> 01:32:09.320
But now we have a new
scrollable behavior.

01:32:09.320 --> 01:32:10.580
And then all we need to do--

01:32:10.580 --> 01:32:12.470
we would say, oops--

01:32:12.470 --> 01:32:13.970
not that.

01:32:13.970 --> 01:32:17.360
If-- once again, I can't type.

01:32:17.360 --> 01:32:23.150
Transform.position.x is
less than negative 25,

01:32:23.150 --> 01:32:25.850
destroy game object, right?

01:32:25.850 --> 01:32:30.510
And so this is the exact same thing as
all that behavior that we saw before.

01:32:30.510 --> 01:32:35.120
So now we can take all
of that out of coin--

01:32:35.120 --> 01:32:38.450
we can take this out, and we
can take this out here, and then

01:32:38.450 --> 01:32:42.710
just add to the airplane
and to the coin prefabs,

01:32:42.710 --> 01:32:44.600
we'd just add this
new Scrollable prefab,

01:32:44.600 --> 01:32:45.680
and it'll take care of that for us.

01:32:45.680 --> 01:32:46.180
Yeah.

01:32:46.180 --> 01:32:48.330
AUDIENCE: How would you add that?

01:32:48.330 --> 01:32:50.330
COLTON OGDEN: So if we're
going back to Unity--

01:32:50.330 --> 01:32:54.230
so the question is, how would you
add the component to the prefab?

01:32:54.230 --> 01:32:57.410
So in our prefabs, note that
we have airplane, we have coin,

01:32:57.410 --> 01:32:58.940
and we have all the skyscrapers.

01:32:58.940 --> 01:33:00.169
So these are all prefabs.

01:33:00.169 --> 01:33:02.210
Oh, and I haven't actually
detailed how to create

01:33:02.210 --> 01:33:04.700
a prefab, which I apologize for.

01:33:04.700 --> 01:33:08.429
So a prefab-- all you need to do
is create an object in your scene.

01:33:08.429 --> 01:33:10.220
For example, I did it
with this helicopter.

01:33:10.220 --> 01:33:13.700
So I'm going to delete the helicopter,
because this is just the helicopter

01:33:13.700 --> 01:33:14.240
prefab.

01:33:14.240 --> 01:33:17.660
It's not going to actually delete
the helicopter from our scene.

01:33:17.660 --> 01:33:24.796
But if I take this helicopter
here, and then I drag it in here,

01:33:24.796 --> 01:33:29.720
notice that now we have a prefab here.

01:33:29.720 --> 01:33:33.120
We could take this helicopter out,
and just add a new one right there.

01:33:33.120 --> 01:33:36.490
So now I have two helicopters.

01:33:36.490 --> 01:33:37.700
That's all a prefab is.

01:33:37.700 --> 01:33:40.070
It's just something that
you've made in your scene

01:33:40.070 --> 01:33:44.780
that you want to replicate or duplicate
in the future, ideally through code.

01:33:44.780 --> 01:33:50.870
And notice it's showing
here in our hierarchy view.

01:33:50.870 --> 01:33:53.780
But obviously you don't want that.

01:33:53.780 --> 01:33:57.290
But that's how you create a
prefab is, you find something

01:33:57.290 --> 01:34:01.850
that you've configured in your
game scene, and then in your code,

01:34:01.850 --> 01:34:04.220
you're allowed to then
instantiate that prefab,

01:34:04.220 --> 01:34:10.400
assuming that you've made that
prefab a member of whatever class

01:34:10.400 --> 01:34:11.210
instantiates it.

01:34:11.210 --> 01:34:13.940
So in this case, the airplane spawner.

01:34:13.940 --> 01:34:18.430
So notice that we call Instantiate
here, like we saw, before on line 24.

01:34:18.430 --> 01:34:21.130
But it's looking at prefabs.

01:34:21.130 --> 01:34:24.980
It's a list, and it's looking
at a random range between 0

01:34:24.980 --> 01:34:27.560
and the length of the prefabs.

01:34:27.560 --> 01:34:31.280
You have to declare a public
GameObject list prefabs here.

01:34:31.280 --> 01:34:35.330
And then, once we do that, and we
go to our airplane spawner here,

01:34:35.330 --> 01:34:38.300
notice that we have
this prefabs list here.

01:34:38.300 --> 01:34:44.450
So we actually get a editor view
of that code, that data structure.

01:34:44.450 --> 01:34:48.770
And we can just add
prefabs that we want to.

01:34:48.770 --> 01:34:54.560
And if we change the size to 2,
then we can add a second prefab.

01:34:54.560 --> 01:34:59.360
Or if we make the size 10, then we
can put 10 different airplanes there.

01:34:59.360 --> 01:35:02.800
But we only have one airplane that I
modeled, so I was going to make it 1.

01:35:02.800 --> 01:35:05.480
But this is the same thing.

01:35:05.480 --> 01:35:08.720
This GameObject list
is that same list, only

01:35:08.720 --> 01:35:10.910
that's the view we have
of it in the editor.

01:35:10.910 --> 01:35:13.730
And it's just a different
way of looking at the data.

01:35:13.730 --> 01:35:16.790
And that's the nice thing about
Unity is that, if you make

01:35:16.790 --> 01:35:19.640
any of your fields public, like this.

01:35:19.640 --> 01:35:24.590
If I did public int someNumber, right?

01:35:24.590 --> 01:35:27.590
And I save that, and I go
back here, my airplane spawner

01:35:27.590 --> 01:35:32.510
should get a someNumber right here.

01:35:32.510 --> 01:35:34.760
And then I can just set
someNumber to whatever I want.

01:35:34.760 --> 01:35:36.290
It doesn't do anything right
now, because someNumber

01:35:36.290 --> 01:35:37.860
doesn't affect the script.

01:35:37.860 --> 01:35:44.090
But this is a nice way to take the
burden from you out of the code.

01:35:44.090 --> 01:35:46.910
You're not experimenting with code.

01:35:46.910 --> 01:35:49.120
You're not tweaking some
variable in your script.

01:35:49.120 --> 01:35:52.810
SomeNumber 10, run me,
OK-- someNumber 12, run it.

01:35:52.810 --> 01:35:56.680
You can just assign it here
in your actual editor view,

01:35:56.680 --> 01:35:58.227
and then just tweak it as you want.

01:35:58.227 --> 01:35:59.560
So I can just scroll through it.

01:35:59.560 --> 01:36:03.010
I can start the game and
I can pause the game.

01:36:03.010 --> 01:36:05.082
AUDIENCE: So is it that
you just make it public?

01:36:05.082 --> 01:36:06.790
COLTON OGDEN: You have
to make it public.

01:36:06.790 --> 01:36:07.240
Exactly.

01:36:07.240 --> 01:36:08.320
AUDIENCE: Oh, then that shows in.

01:36:08.320 --> 01:36:09.070
COLTON OGDEN: Yep.

01:36:09.070 --> 01:36:10.240
And so I can just do this.

01:36:10.240 --> 01:36:11.490
And then I should be able to--

01:36:11.490 --> 01:36:14.170
I can just change this
now, if I wanted to, to 67.

01:36:14.170 --> 01:36:18.070
And so if that actually had some
sort of effect on my game world--

01:36:18.070 --> 01:36:21.490
if my game relied on that
number being meaningful--

01:36:21.490 --> 01:36:22.980
this would update the scene.

01:36:22.980 --> 01:36:25.540
And so you can make whatever--
you can debug this way,

01:36:25.540 --> 01:36:29.190
or you can customize your
components more this way.

01:36:29.190 --> 01:36:33.220
But it's just a tremendous
amount of flexibility.

01:36:33.220 --> 01:36:37.630
And so that's how we're instantiating
this from this list of prefabs.

01:36:37.630 --> 01:36:39.640
It's a list of game objects.

01:36:39.640 --> 01:36:42.460
We've made it explicit to Unity.

01:36:42.460 --> 01:36:45.580
The editor's going to know,
OK, these are game objects.

01:36:45.580 --> 01:36:47.710
And so prefabs are game objects.

01:36:47.710 --> 01:36:51.520
So we can just put any
of these into this field

01:36:51.520 --> 01:36:55.870
here, this element 0 field, or
however many fields we have.

01:36:55.870 --> 01:36:59.410
And it will, in the code,
randomly choose one of those,

01:36:59.410 --> 01:37:01.690
and then instantiate it.

01:37:01.690 --> 01:37:04.374
So any questions as to how
prefabs work, or instantiation,

01:37:04.374 --> 01:37:05.290
or anything like that?

01:37:07.721 --> 01:37:08.220
OK.

01:37:11.118 --> 01:37:14.500
AUDIENCE: Does each prefab
have a unique number or not?

01:37:14.500 --> 01:37:16.750
COLTON OGDEN: Does each
prefab have a unique number?

01:37:16.750 --> 01:37:18.250
Not a unique number.

01:37:18.250 --> 01:37:21.880
They just are all assets
in your folder here.

01:37:21.880 --> 01:37:26.170
They have some kind of identifier
to Unity that's hidden from you.

01:37:26.170 --> 01:37:28.180
It might be visible
from you if you look.

01:37:28.180 --> 01:37:31.180
They might have some sort of generated
ID or something like that, so

01:37:31.180 --> 01:37:33.380
that it knows, underneath the scenes.

01:37:33.380 --> 01:37:38.380
But it's not something that you
worry about in your actual code.

01:37:38.380 --> 01:37:41.540
We've created a list here that's just--

01:37:41.540 --> 01:37:43.720
it will expect some number.

01:37:43.720 --> 01:37:44.832
It doesn't know how many.

01:37:44.832 --> 01:37:47.290
And then, in the editor, you
can actually tell it how many.

01:37:50.830 --> 01:37:55.630
Because every list that
you make visible in

01:37:55.630 --> 01:37:58.420
the editor will have this size field.

01:37:58.420 --> 01:38:00.850
And that's just part of
the editor's abstraction.

01:38:00.850 --> 01:38:04.030
The editor has abstractions
for a lot of different objects.

01:38:04.030 --> 01:38:07.630
You can create a lot of different
objects in your MonoBehaviours,

01:38:07.630 --> 01:38:12.220
and make them public, and Unity
will have a different view for them.

01:38:12.220 --> 01:38:14.596
Things like color pickers,
and stuff like that.

01:38:14.596 --> 01:38:17.470
I don't know the exact object offhand,
but if you make a public color

01:38:17.470 --> 01:38:20.081
picker in your MonoBehaviour
or something like that,

01:38:20.081 --> 01:38:23.080
you'll actually get a color picker
here that you can choose a color for,

01:38:23.080 --> 01:38:24.560
which is pretty awesome.

01:38:24.560 --> 01:38:27.190
And there's a lot of
different customized views.

01:38:30.529 --> 01:38:33.070
I think, actually, the directional
light might be an example.

01:38:33.070 --> 01:38:34.510
See this color here?

01:38:34.510 --> 01:38:37.300
This is somewhere in code.

01:38:37.300 --> 01:38:40.040
There's a public color something.

01:38:40.040 --> 01:38:42.520
And then in the editor, when
you're actually editing it,

01:38:42.520 --> 01:38:43.600
you can choose the color.

01:38:43.600 --> 01:38:46.400
And Unity gives you the option
to make it wherever you want.

01:38:46.400 --> 01:38:50.740
And notice it's actually
affecting the background there.

01:38:50.740 --> 01:38:52.690
One of the really big
strengths of Unity,

01:38:52.690 --> 01:38:56.350
and a reason to really make
your components customizable,

01:38:56.350 --> 01:39:01.390
is this one-to-one mapping
between your data, your code,

01:39:01.390 --> 01:39:05.485
and your editor view of the data.

01:39:05.485 --> 01:39:07.360
Take the burden away
from you programming it,

01:39:07.360 --> 01:39:10.630
which you're more prone
to make mistakes, too,

01:39:10.630 --> 01:39:12.640
and also waste a lot of time.

01:39:12.640 --> 01:39:14.620
And then just be able to modify.

01:39:14.620 --> 01:39:16.900
How much faster is it
for me to just say,

01:39:16.900 --> 01:39:20.470
I want this red color, rather
than color.r equals something,

01:39:20.470 --> 01:39:23.440
and then color.g equals something,
color.b equals something.

01:39:23.440 --> 01:39:24.800
And then assign it that way.

01:39:24.800 --> 01:39:26.841
So that's just a simple
example to illustrate it.

01:39:26.841 --> 01:39:29.890
But there's a tremendous
amount of potential involved

01:39:29.890 --> 01:39:33.320
in making your components customizable.

01:39:33.320 --> 01:39:34.570
And so that's what I did here.

01:39:34.570 --> 01:39:43.270
Because I wanted the skyscraper spawner
to spawn not just one skyscraper

01:39:43.270 --> 01:39:48.160
but several skyscrapers, I
created this public prefabs list,

01:39:48.160 --> 01:39:50.770
that I can then populate
from Unity here.

01:39:50.770 --> 01:39:53.620
And say, OK, this object,
this object, and this object.

01:39:53.620 --> 01:39:56.560
Put that into the skyscraper
spawner here, in these slots.

01:39:56.560 --> 01:40:02.200
And then my code knows to instantiate
it, randomly picking one of those.

01:40:02.200 --> 01:40:02.700
Yeah.

01:40:02.700 --> 01:40:04.986
AUDIENCE: In the example
earlier, how would you

01:40:04.986 --> 01:40:09.560
actually go about making something
scrollable now that you've made that?

01:40:09.560 --> 01:40:12.329
Would you just add
component to the coin?

01:40:12.329 --> 01:40:15.370
COLTON OGDEN: How would you go about
making something scrollable now that

01:40:15.370 --> 01:40:15.869
you've--

01:40:15.869 --> 01:40:18.670
AUDIENCE: You declared that
Scrollable class, right?

01:40:18.670 --> 01:40:19.690
COLTON OGDEN: Oh, yeah.

01:40:19.690 --> 01:40:24.550
So I have a Scrollable script here.

01:40:24.550 --> 01:40:28.507
Oh, do you mean the infinite scrolling
background, or the scrollable object?

01:40:28.507 --> 01:40:31.840
AUDIENCE: The one where you define it as
being destroyed when it's [INAUDIBLE]..

01:40:31.840 --> 01:40:32.798
COLTON OGDEN: Oh, yeah.

01:40:32.798 --> 01:40:35.780
So in order to do that-- so we've
made the Scrollable script here.

01:40:35.780 --> 01:40:38.050
So you would just go to--
in this case, since we're

01:40:38.050 --> 01:40:42.340
instantiating all of the coins, and
skyscrapers, and airplanes as prefabs,

01:40:42.340 --> 01:40:44.470
you actually edit the prefab itself.

01:40:44.470 --> 01:40:46.160
So I'd go to this coin prefab.

01:40:46.160 --> 01:40:48.370
I'd add component here at the bottom.

01:40:48.370 --> 01:40:51.580
And I would add Scrollable
there, which is a script.

01:40:51.580 --> 01:40:54.070
And you can tell it's yours,
because it says script there.

01:40:54.070 --> 01:40:57.460
Just like coin here is a script,
and rotate script is a script.

01:40:57.460 --> 01:41:01.110
That's actually an old script
that I didn't use anymore,

01:41:01.110 --> 01:41:05.200
because I just made it
part of the coin itself.

01:41:05.200 --> 01:41:08.380
But this is another part of what
makes the coin class, by the way,

01:41:08.380 --> 01:41:14.590
is this transform.rotate x,
y, and z, either relative

01:41:14.590 --> 01:41:16.340
to itself or to the world space.

01:41:16.340 --> 01:41:18.590
In this case, it shows the
world space, because I want

01:41:18.590 --> 01:41:20.370
it to rotate on the world's y-axis.

01:41:20.370 --> 01:41:24.227
But if you rotate an object,
its own x, y, z still exist.

01:41:24.227 --> 01:41:26.560
And so you can have something
rotate about its own x, y,

01:41:26.560 --> 01:41:29.574
and z, regardless of its
rotation in the world.

01:41:29.574 --> 01:41:31.240
And so I want the coin to always rotate.

01:41:31.240 --> 01:41:35.450
So 5 degrees on the y-axis here.

01:41:35.450 --> 01:41:40.030
So this is another part that you could
take and make it its own script--

01:41:40.030 --> 01:41:42.190
just a rotatable script.

01:41:42.190 --> 01:41:43.390
Auto rotate script.

01:41:43.390 --> 01:41:47.590
And then just make these public fields,
like public x, public y, public z.

01:41:47.590 --> 01:41:49.570
And then you could change
those in the editor,

01:41:49.570 --> 01:41:54.970
and then actually customize your objects
without having to go into the code

01:41:54.970 --> 01:41:56.324
itself.

01:41:56.324 --> 01:42:00.300
AUDIENCE: So you don't have to do
any collisions, actually, yourself.

01:42:00.300 --> 01:42:04.019
You just click the button and
type in the Collide function.

01:42:04.019 --> 01:42:04.810
COLTON OGDEN: Yeah.

01:42:04.810 --> 01:42:06.934
You don't have to do any
of the collision yourself,

01:42:06.934 --> 01:42:09.744
because Unity comes with
a 3D physics engine.

01:42:09.744 --> 01:42:12.160
You have to tell it what to
do when the collisions happen.

01:42:12.160 --> 01:42:16.750
But you don't have to actually code
the 3D physics engine yourself, which

01:42:16.750 --> 01:42:19.710
is a tremendous amount of work.

01:42:19.710 --> 01:42:21.460
One of the big selling
points, definitely,

01:42:21.460 --> 01:42:23.410
for doing any 3D things in Unity.

01:42:23.410 --> 01:42:26.800
I mean, a lot of engines now
have 3D engines for free.

01:42:26.800 --> 01:42:29.202
There was a time when
it was less prevalent.

01:42:29.202 --> 01:42:31.619
AUDIENCE: How would you
know what you collided with?

01:42:31.619 --> 01:42:33.910
COLTON OGDEN: Because there
is a collider that it gets.

01:42:38.331 --> 01:42:39.080
Where is it again?

01:42:39.080 --> 01:42:41.572
Is it the skyscraper, for example?

01:42:41.572 --> 01:42:43.780
So every skyscraper, when
it collides with something,

01:42:43.780 --> 01:42:47.320
this OnTriggerEnter gets
passed in this collider other.

01:42:47.320 --> 01:42:53.014
And so that's going to be the
object that you collided with.

01:42:53.014 --> 01:42:56.180
You can assign a name to an object, and
then get its name, as well, in code,

01:42:56.180 --> 01:42:58.599
if you needed to do that.

01:42:58.599 --> 01:43:01.390
In this case, we wanted to know
whether it's the helicopter or not.

01:43:01.390 --> 01:43:04.160
So we got the HeliController from it.

01:43:04.160 --> 01:43:06.280
But in our game, it's
kind of a special case,

01:43:06.280 --> 01:43:08.290
because there's only
one type of object that

01:43:08.290 --> 01:43:11.500
has a collider that's a non-trigger,
and that's the helicopter.

01:43:11.500 --> 01:43:15.400
So we can assume that this exists
when we do get a collision.

01:43:15.400 --> 01:43:20.410
But otherwise, we probably want to
say, get component of HeliController,

01:43:20.410 --> 01:43:22.340
and then test it for equal to null.

01:43:22.340 --> 01:43:26.500
And if it's equal to null, then
we want to not do something.

01:43:26.500 --> 01:43:29.587
If we tried to call
explode on a null object,

01:43:29.587 --> 01:43:31.420
that's going to be a
null pointer exception.

01:43:31.420 --> 01:43:33.624
And then you're going
to crash your game.

01:43:33.624 --> 01:43:36.040
But in this case, we're
guaranteed for that not to happen.

01:43:36.040 --> 01:43:38.530
Because, like I said,
the only collider that

01:43:38.530 --> 01:43:42.900
can collide with this that's not a
trigger is the helicopter object.

01:43:42.900 --> 01:43:45.085
So does that makes sense?

01:43:45.085 --> 01:43:48.480
AUDIENCE: Sounds like a physics
problem with an exploding element.

01:43:48.480 --> 01:43:49.640
COLTON OGDEN: Oh, yeah.

01:43:49.640 --> 01:43:50.280
Yeah.

01:43:50.280 --> 01:43:52.230
That's all too real.

01:43:55.370 --> 01:43:59.196
In this case, though, all explode is
is, thankfully, just destroy game object

01:43:59.196 --> 01:44:00.570
and then start a particle effect.

01:44:00.570 --> 01:44:04.800
So any more questions
as to how instantiation,

01:44:04.800 --> 01:44:08.610
prefabs, using the Unity editor,
interacting with your model

01:44:08.610 --> 01:44:10.330
behaviors, public variables?

01:44:10.330 --> 01:44:11.905
Yeah.

01:44:11.905 --> 01:44:15.300
AUDIENCE: You get processes, you
first enter the data in that to there,

01:44:15.300 --> 01:44:19.665
and then it runs the
code to load the data,

01:44:19.665 --> 01:44:23.070
or can you also put
value data in the editor?

01:44:23.070 --> 01:44:24.480
COLTON OGDEN: You cannot define--

01:44:24.480 --> 01:44:27.570
so the question is, do you first
create the data in the editor,

01:44:27.570 --> 01:44:31.380
and then the code, and then
tie them together that way?

01:44:31.380 --> 01:44:34.650
In order to get a new component, you
will have to create the class first--

01:44:34.650 --> 01:44:37.440
the model behavior that you want--

01:44:37.440 --> 01:44:41.550
and give it the public fields that it
needs for the editor to actually read.

01:44:41.550 --> 01:44:45.000
So the editor reads your script,
looks through all the public fields,

01:44:45.000 --> 01:44:47.820
and then will create the necessary
GUI elements in the editor

01:44:47.820 --> 01:44:50.020
to interact with the code.

01:44:50.020 --> 01:44:51.390
But this needs to exist.

01:44:51.390 --> 01:44:52.980
All this code needs to exist.

01:44:52.980 --> 01:44:56.430
Anything that has these public variables
that you want accessible in the editor

01:44:56.430 --> 01:44:59.130
needs to exist in code
first, and then you

01:44:59.130 --> 01:45:00.900
have the power to use it in the editor.

01:45:00.900 --> 01:45:04.440
And then it's customizable
at that point.

01:45:04.440 --> 01:45:08.130
Any more questions?

01:45:08.130 --> 01:45:09.540
All right.

01:45:09.540 --> 01:45:11.460
So that's the prefabs.

01:45:11.460 --> 01:45:13.456
So we looked at texture
scrolling before.

01:45:13.456 --> 01:45:15.580
And we're going to go kind
of quickly through this.

01:45:15.580 --> 01:45:18.220
But all texture showing
was, if we recall,

01:45:18.220 --> 01:45:21.450
was I have a scrolling
background class here.

01:45:21.450 --> 01:45:22.510
It's got a scroll speed.

01:45:22.510 --> 01:45:25.387
So if we wanted to, since it's
public, we can edit it in the editor

01:45:25.387 --> 01:45:26.595
and make it faster or slower.

01:45:29.170 --> 01:45:31.230
But if we maintain a
reference to our renderer.

01:45:31.230 --> 01:45:35.550
Every object has a renderer-- mesh
renderer, typically, for 3D objects.

01:45:35.550 --> 01:45:39.900
And the renderer has a
material associated with it.

01:45:39.900 --> 01:45:43.230
Everything in Unity has a material.

01:45:43.230 --> 01:45:45.660
And material doesn't
necessarily have a texture.

01:45:45.660 --> 01:45:48.570
But in this case, our
background does have a texture,

01:45:48.570 --> 01:45:51.000
and it's going to be
called MainTex by default.

01:45:51.000 --> 01:45:53.910
That's the main texture, if
we want to assign a texture

01:45:53.910 --> 01:45:55.920
to see visually on a material.

01:45:55.920 --> 01:45:59.700
So material can just be a
color often, but it can also

01:45:59.700 --> 01:46:02.350
be a color and also a texture.

01:46:02.350 --> 01:46:04.410
So in this case, the
background is a texture.

01:46:04.410 --> 01:46:05.993
It does have a texture assigned to it.

01:46:05.993 --> 01:46:09.810
And notice that if we
go to the background,

01:46:09.810 --> 01:46:13.590
and then here is where
we actually create.

01:46:13.590 --> 01:46:15.360
So this is a material here.

01:46:15.360 --> 01:46:16.530
It's got a shader.

01:46:16.530 --> 01:46:19.037
So we're not going to talk too
much about what shaders are.

01:46:19.037 --> 01:46:20.370
We've talked about them briefly.

01:46:20.370 --> 01:46:24.720
In Unity, you can go quite
a bit farther with them.

01:46:24.720 --> 01:46:28.860
Well, technically speaking, I guess
you could go equally far with Love2D--

01:46:28.860 --> 01:46:34.290
2D shaders and 3D shaders, at least
in vertex and fragment shaders.

01:46:34.290 --> 01:46:37.590
But for all intents
and purposes, we're not

01:46:37.590 --> 01:46:40.560
going to go into detail
on shaders today.

01:46:40.560 --> 01:46:42.690
But they're very similar.

01:46:42.690 --> 01:46:47.247
In this case, every material
has a shader in Unity,

01:46:47.247 --> 01:46:48.330
in order for it to render.

01:46:48.330 --> 01:46:52.170
Because anything that renders
needs to be shaded in Unity.

01:46:52.170 --> 01:46:54.340
But notice that here we have a texture.

01:46:54.340 --> 01:46:57.100
So this is that main texture
thing that we saw before.

01:46:57.100 --> 01:46:58.904
And then this is the bump map here.

01:46:58.904 --> 01:47:01.320
We don't have a bump map,
because our texture isn't bumpy.

01:47:01.320 --> 01:47:04.170
It doesn't have any contour
detail or anything like that.

01:47:04.170 --> 01:47:06.300
But you can just select a texture here.

01:47:06.300 --> 01:47:08.670
So I could give it that
texture if I wanted to.

01:47:08.670 --> 01:47:10.440
Or I have another
couple of textures here.

01:47:13.730 --> 01:47:14.910
This texture here.

01:47:14.910 --> 01:47:18.120
It doesn't matter which texture you
choose, but you can choose a texture.

01:47:18.120 --> 01:47:21.810
And then that material will
then, it will calculate,

01:47:21.810 --> 01:47:25.770
based on the mesh, how to
draw that texture best to it.

01:47:25.770 --> 01:47:32.520
And you can set every material's
texture offset via its SetTextureOffset

01:47:32.520 --> 01:47:34.800
function on the x and the y-axis.

01:47:34.800 --> 01:47:38.850
And that'll shift it,
effectively accomplishing

01:47:38.850 --> 01:47:41.010
what a scrolling background needs.

01:47:41.010 --> 01:47:44.340
It'll draw it, and then it'll basically
wrap around to the other side.

01:47:44.340 --> 01:47:48.330
So that's how we get the
infinite scrolling texture.

01:47:48.330 --> 01:47:51.050
We just set its texture offset.

01:47:51.050 --> 01:47:54.480
We specific call SetTextureOffset
on the main texture,

01:47:54.480 --> 01:47:55.910
and then we pass in a Vector 2.

01:47:55.910 --> 01:47:57.720
So just two numbers--

01:47:57.720 --> 01:47:58.650
offset and 0.

01:47:58.650 --> 01:48:01.920
Because we don't want to touch the
y-axis, so it was 0, and then offset

01:48:01.920 --> 01:48:04.590
is just some value that
increases over time.

01:48:04.590 --> 01:48:06.390
And then Time.time, recall--

01:48:06.390 --> 01:48:08.640
time since the beginning
of the game has started.

01:48:08.640 --> 01:48:11.550
Time.delta time-- time
since the last frame.

01:48:11.550 --> 01:48:15.480
And so we can just do one calculation
in here and update every time,

01:48:15.480 --> 01:48:17.610
and then multiply it
times scroll speed to get

01:48:17.610 --> 01:48:19.440
the scroll amount that we want here.

01:48:19.440 --> 01:48:23.710
And I've set it to 0.1 just
for a semi-slow effect.

01:48:23.710 --> 01:48:32.170
But in the editor, if we look at our
scrolling background, which is here.

01:48:32.170 --> 01:48:36.584
And then I've made it public, so
I could just easily make this 1.

01:48:36.584 --> 01:48:39.250
And I don't know how fast it's
going to be, but 10 times faster.

01:48:39.250 --> 01:48:41.334
So probably pretty fast.

01:48:41.334 --> 01:48:42.650
Yep.

01:48:42.650 --> 01:48:45.200
So it's hauling.

01:48:45.200 --> 01:48:45.840
But yeah.

01:48:45.840 --> 01:48:50.310
All that is is a shifting how it
maps the texture onto the 3D surface.

01:48:50.310 --> 01:48:53.760
And this 3D surface, to
be clear, is just a plane.

01:48:53.760 --> 01:48:55.350
So just a plane.

01:48:55.350 --> 01:48:57.600
And notice that it doesn't
get rendered from the back.

01:48:57.600 --> 01:49:02.970
So anything which is a polygon
has one side that gets shaded

01:49:02.970 --> 01:49:05.560
and one side that does not get shaded.

01:49:05.560 --> 01:49:09.522
So if you see invisibility on one
side, and not invisibility on one side,

01:49:09.522 --> 01:49:10.230
that's not a bug.

01:49:10.230 --> 01:49:12.807
That's a feature.

01:49:12.807 --> 01:49:14.640
That's the texture
scrolling side of things.

01:49:14.640 --> 01:49:18.160
Anybody have any questions
as to how that works?

01:49:18.160 --> 01:49:20.747
We won't really need it
for much going forward.

01:49:20.747 --> 01:49:22.080
It's not part of the assignment.

01:49:22.080 --> 01:49:24.500
But it ties in to what
we've done before.

01:49:24.500 --> 01:49:27.214
So I thought it would
be interesting to cover.

01:49:27.214 --> 01:49:28.630
Last thing we'll look at is audio.

01:49:28.630 --> 01:49:30.190
Audio is pretty easy.

01:49:30.190 --> 01:49:37.440
All you need in Unity to do audio is
an audio source and an audio listener.

01:49:37.440 --> 01:49:39.150
So a source plays audio.

01:49:39.150 --> 01:49:44.670
So James, if you are an audio
source, I'd be an audio listener.

01:49:44.670 --> 01:49:46.920
And I'm listening for
audio and playing it back

01:49:46.920 --> 01:49:52.770
to the speakers when I hear any sort
of source of audio in the game world.

01:49:52.770 --> 01:49:56.820
So you can have infinite audio sources,
but ideally one audio listener.

01:49:56.820 --> 01:50:02.550
And it's usually whatever main
camera that you're drawing with.

01:50:02.550 --> 01:50:05.520
And then sounds in Unity
can be either 2D or 3D.

01:50:05.520 --> 01:50:10.110
In this case, all the sounds that
I've put into this game are 2D.

01:50:10.110 --> 01:50:12.560
And that's just this spatial blend here.

01:50:12.560 --> 01:50:15.570
Notice that there's a 2D to 3D slide.

01:50:15.570 --> 01:50:17.820
And so that'll calculate,
based on where the sound is,

01:50:17.820 --> 01:50:19.380
how it sounds in the game space.

01:50:19.380 --> 01:50:23.430
And it's based on how far away it
is, and what side of you it is.

01:50:23.430 --> 01:50:27.150
And so the main camera has the
audio source for the music.

01:50:27.150 --> 01:50:29.730
And so it just starts
the music right away.

01:50:29.730 --> 01:50:31.870
Notice that we didn't
have to code any of this.

01:50:31.870 --> 01:50:34.000
I just attached an audio
source to the camera.

01:50:34.000 --> 01:50:38.340
And then there's a Play On Awake
checkbox, and a Loop checkbox.

01:50:38.340 --> 01:50:40.260
So normally we've done like--

01:50:40.260 --> 01:50:43.650
at the start of our game code,
set looping to true, and then

01:50:43.650 --> 01:50:44.595
play the source.

01:50:44.595 --> 01:50:46.720
In this case, we'd have to
do none of those things.

01:50:46.720 --> 01:50:49.260
This is just given to
us by Unity by default.

01:50:49.260 --> 01:50:51.106
AUDIENCE: You put the
audio on the camera?

01:50:51.106 --> 01:50:51.855
COLTON OGDEN: Yep.

01:50:51.855 --> 01:50:53.070
AUDIENCE: You could put it on anything.

01:50:53.070 --> 01:50:54.876
COLTON OGDEN: You could put
it on anything you want to.

01:50:54.876 --> 01:50:56.700
AUDIENCE: The sound is
relative to that object.

01:50:56.700 --> 01:50:59.075
COLTON OGDEN: The sound is
relative to that object, yeah.

01:51:01.439 --> 01:51:01.980
That's audio.

01:51:01.980 --> 01:51:03.420
It's pretty simple.

01:51:03.420 --> 01:51:05.460
I mean, it's an art form
when it comes to how

01:51:05.460 --> 01:51:06.840
you want to position
things in your game world,

01:51:06.840 --> 01:51:09.030
and how you want them
to sound, and whatnot.

01:51:09.030 --> 01:51:10.738
And you can get more
complicated with it.

01:51:10.738 --> 01:51:14.360
But that's how you would do
basic 2D, in this case, audio.

01:51:14.360 --> 01:51:16.110
But you could easily
also do 3D audio just

01:51:16.110 --> 01:51:19.620
by making this set to 0 from 0 to 1.

01:51:19.620 --> 01:51:21.660
And you can make it
more or less 3D, too.

01:51:21.660 --> 01:51:24.290
If it's not all the way to
1, it'll somewhat be 2D.

01:51:24.290 --> 01:51:27.660
So you'll hear some of it no matter
what, and some of it will be 3D.

01:51:27.660 --> 01:51:29.977
And then setting it to
1, it'll be purely 3D.

01:51:29.977 --> 01:51:32.310
So if it gets far enough away,
you won't hear it at all.

01:51:35.640 --> 01:51:40.240
The explosion sound, as
well, gets triggered.

01:51:40.240 --> 01:51:41.520
And so this happens in the--

01:51:41.520 --> 01:51:44.130
I forget exactly offhand
where it gets triggered.

01:51:49.000 --> 01:51:55.020
I believe it's in the
HelicopterExplode function?

01:51:55.020 --> 01:51:55.590
Oh, yes.

01:52:01.435 --> 01:52:04.560
I created an object in the scene that
has an audio source for the explosion

01:52:04.560 --> 01:52:05.220
sound.

01:52:05.220 --> 01:52:08.470
And because I made this public,
I can just put it on this object.

01:52:08.470 --> 01:52:12.130
And so there's a reference to
that audio source at all times.

01:52:12.130 --> 01:52:16.230
And so I trigger explosionSound.play
whenever we call this Explode method

01:52:16.230 --> 01:52:17.754
on the HeliController.

01:52:17.754 --> 01:52:20.670
For the reason that I didn't put it
on this object, because we destroy

01:52:20.670 --> 01:52:24.180
this object as soon as
we get into a collision.

01:52:24.180 --> 01:52:27.515
And so I didn't want to
put the explosion sound

01:52:27.515 --> 01:52:30.390
audio source on this object, because
it would get destroyed in there.

01:52:30.390 --> 01:52:33.270
It would not play audio, effectively,
as soon as we destroy it.

01:52:33.270 --> 01:52:35.380
So we have to have it
somewhere else on the scene.

01:52:35.380 --> 01:52:40.505
I could have also just made the
object invisible, but I didn't.

01:52:40.505 --> 01:52:41.130
I destroyed it.

01:52:44.670 --> 01:52:46.270
And so, yeah.

01:52:46.270 --> 01:52:51.930
That's this explosion sound object
which, if we look at the helicopter,

01:52:51.930 --> 01:52:57.910
in the HeliController, which
is all the way down here.

01:52:57.910 --> 01:53:01.780
Notice that it has a reference
to an explosion particle

01:53:01.780 --> 01:53:03.760
system and an explosion sound.

01:53:03.760 --> 01:53:08.320
And we just have to click and drag the
object effectively from here to here

01:53:08.320 --> 01:53:09.550
to pair the two of them.

01:53:09.550 --> 01:53:11.710
And then the script
that this is referring

01:53:11.710 --> 01:53:14.170
to will always have a reference
to those, as long as these

01:53:14.170 --> 01:53:15.580
are set to something.

01:53:15.580 --> 01:53:18.010
And notice that we also have
coin total we've made public.

01:53:18.010 --> 01:53:19.660
So I guess I could experiment with it.

01:53:19.660 --> 01:53:22.900
And then speed-- we made this public
so that you can make the helicopter

01:53:22.900 --> 01:53:25.100
faster, if you wanted to, or slower.

01:53:25.100 --> 01:53:30.987
And so you'll find it often useful
to make a lot of these fields public

01:53:30.987 --> 01:53:32.320
just for you to experiment with.

01:53:32.320 --> 01:53:34.930
And then there's never
really harm in doing so,

01:53:34.930 --> 01:53:39.452
because folks aren't going to be able
to actually see this in the editor

01:53:39.452 --> 01:53:40.660
when they download your game.

01:53:40.660 --> 01:53:43.210
So make as much public as you
want for debugging purposes,

01:53:43.210 --> 01:53:46.027
and just have fun with it.

01:53:46.027 --> 01:53:46.735
But that's audio.

01:53:46.735 --> 01:53:48.600
Audio sources produce the sound.

01:53:48.600 --> 01:53:50.260
Audio listeners listen to the sound.

01:53:50.260 --> 01:53:53.050
And actually make it go
through your computer speakers

01:53:53.050 --> 01:53:57.460
or whatever your
default audio system is.

01:53:57.460 --> 01:54:01.360
And here's just a showcase
of the two on the camera.

01:54:01.360 --> 01:54:03.070
And that's audio.

01:54:03.070 --> 01:54:08.384
So any questions as to how
the audio works at all?

01:54:08.384 --> 01:54:09.280
All right.

01:54:09.280 --> 01:54:11.321
A couple of last things
before we close out here.

01:54:11.321 --> 01:54:14.380
So the Asset Store is probably one
of the biggest things about Unity

01:54:14.380 --> 01:54:16.630
that sells it.

01:54:16.630 --> 01:54:20.590
So oftentimes, it's a lot
easier just to get something,

01:54:20.590 --> 01:54:23.560
whether it's a library, if you're
programming, or something else,

01:54:23.560 --> 01:54:25.930
get something that's
implemented for you,

01:54:25.930 --> 01:54:29.950
so that you don't have
to implement it yourself.

01:54:29.950 --> 01:54:32.680
In this case, there's an RPG
Systems for Rapid Development

01:54:32.680 --> 01:54:36.850
something, Visual Scripting
system, looks similar to Unreal.

01:54:36.850 --> 01:54:43.990
There's a ton of things in the Asset
Store-- models, scripts, audio, editor

01:54:43.990 --> 01:54:44.800
tool kits.

01:54:44.800 --> 01:54:45.820
A lot of cool things.

01:54:45.820 --> 01:54:48.190
A lot of it's free, if
you want to experiment.

01:54:48.190 --> 01:54:52.660
So a lot of the assets that I got
to mess with in this game here

01:54:52.660 --> 01:54:56.312
are free, like the coin and some of
the other stuff that's bundled with it.

01:54:56.312 --> 01:54:58.770
There's a lot of really cool
things and really cool systems

01:54:58.770 --> 01:55:00.340
to help you for $10 or $20.

01:55:00.340 --> 01:55:02.830
You can spend a little
bit of money, and then

01:55:02.830 --> 01:55:06.310
get like 25% of your
game done right away.

01:55:06.310 --> 01:55:08.860
And then you can actually
get closer to shipping it.

01:55:08.860 --> 01:55:12.790
So I think it's hugely valuable
to be looking at the Asset Store

01:55:12.790 --> 01:55:15.310
and thinking about how you
can save your time that way,

01:55:15.310 --> 01:55:18.830
if you're trying to actually
ship a game and get to market.

01:55:18.830 --> 01:55:21.070
So definitely look
through the Asset Store.

01:55:21.070 --> 01:55:24.220
See if there's anything that
will make your life easier

01:55:24.220 --> 01:55:25.930
when it comes to developing games.

01:55:25.930 --> 01:55:30.940
Because I know that I've used it several
times, and I rarely regret doing so.

01:55:30.940 --> 01:55:35.120
So Assignment 8 is going
to be pretty simple.

01:55:35.120 --> 01:55:39.820
So for the second part,
there's a bug in the game

01:55:39.820 --> 01:55:45.400
where, if you die over and over
again, the scroll speed never resets.

01:55:45.400 --> 01:55:48.940
So it is keeping faster, and faster,
and faster, and faster forever.

01:55:48.940 --> 01:55:50.890
But it's a one line fix.

01:55:50.890 --> 01:55:54.010
And I want you guys to find where
to fix it, given that we know,

01:55:54.010 --> 01:55:55.390
given what we've seen today.

01:55:55.390 --> 01:55:57.880
And there's a hint here
about static variables.

01:55:57.880 --> 01:56:01.540
So it will also be detailed
in the spec as well.

01:56:01.540 --> 01:56:03.010
But this is an easy part.

01:56:03.010 --> 01:56:05.665
This part's fairly easy,
too, because all it really is

01:56:05.665 --> 01:56:08.740
is taking the kind of the
same stuff we've looked at--

01:56:08.740 --> 01:56:10.570
the coin generator and coins--

01:56:10.570 --> 01:56:16.780
and then making gems that spawn in
addition to the coins at a rarer rate.

01:56:16.780 --> 01:56:19.150
And these gems should
be worth five coins.

01:56:19.150 --> 01:56:22.765
And so when you collide with the
gems, just add 5 to the coin total.

01:56:22.765 --> 01:56:25.392
And if you collide with a
coin, add 1 to the coin total.

01:56:25.392 --> 01:56:27.100
And that's basically
it for Assignment 8.

01:56:27.100 --> 01:56:31.750
So next time, we're going to dive
into first-person games in Unity.

01:56:31.750 --> 01:56:35.080
So we'll look at some of the
features that we get for free.

01:56:35.080 --> 01:56:39.100
We're going to implement a simple
maze-like game where you can navigate.

01:56:39.100 --> 01:56:41.080
And it will be dark and
kind of scary, similar

01:56:41.080 --> 01:56:43.600
to a game called Dreadhalls,
which is a mobile VR game.

01:56:43.600 --> 01:56:48.160
And we'll actually test out Unity's VR,
and try and get a VR headset in here

01:56:48.160 --> 01:56:51.080
so people can check that out.

01:56:51.080 --> 01:56:51.580
Cool.

01:56:51.580 --> 01:56:52.121
Thanks a lot.

01:56:52.121 --> 01:56:54.030
I'll see you guys next time.