COLTON OGDEN: All right.

Welcome to GD50.

This is lecture 10.

Today we'll be talking about "Portal."

So "Portal" is a very iconic game, I think most of us

have probably seen it before.

The gist is you have a portal gun, a gun that shoots these elliptical portals.

If you look through one, you can effectively

see what is coming out the other one, which is pretty cool, and vise versa.

And then, if you walk in between the portals,

you'll actually be teleported to the other side.

And so, they achieve a lot of really interesting effects

with some pretty cool tricks and stuff.

And actually Valve themselves will be coming

to give a talk on a lot of the technology

that they used on the second.

So we can get a glimpse into their version of "Portal."

My version of "Portal" is a bit simpler, but we'll

look at a lot of the same sort of principles

and see how I accomplished a lot of the same things.

So this is also the last lecture of the semester,

and we've covered a lot of ground.

I have a few screenshots here to show some of the games

that we've talked about.

The very first game was "Pong," and we've come sort of a long way.

We have gone through very simple arcadey Atari-like games like this,

and have gone and created worlds effectively.

And now we're in 3D, we're doing all kinds of awesome stuff.

But this was where we started the course.

And it's kind of fun to look back and see where we've come.

So here, we talked about scoring and just effectively drawing shapes

onto the screen, then we transition to "Flappy Bird" or "50 Bird,"

and we had sprites and characters.

And we talked about scrolling and infinite level procedural generation

type algorithms, and that was fun.

We took things a step higher than that with "Breakout"

where we had the same sort of procedural ideas

in the context of a very famous arcade game.

We talked about particle systems and some arcade style

physics and high scores.

Then we went into puzzle games.

We talked about Match Three" and how to actually calculate

what goes on to determine whether we have gotten a match

and how to clear blocks and how to tween things,

do operations over time, sort of this A synchronicity.

Then we went into probably what is my favorite lecture, which

was "Super Mario Brothers," and we talked

about how to create procedural worlds that all look very different

with some very simple algorithms.

And then we had triggers and events sort of happening.

Then "Legend of Zelda" came, and we had this infinite dungeon algorithm.

And we had enemies walking around that we

could use a sword on, so it felt more like an actual action game, action RPG.

Then took a brief look at physics in the context of Box 2D with "Angry Birds,"

and I still remember the ball pit example was probably

my favorite part of that.

And then probably the most complicated example of the semester

was "Pokemon," where we actually had a semi full turn based

parallel system, and random encounters, and like a little world where there's

actually two main stages to our world where there was the field

and the battle scene, which is a very common thing to have in RPGs.

Following "Pokemon," which was the most complicated codebase,

we went into Unity, which was our first foray into 3D.

And even though we were just exploring 2.5D,

we still got a chance to look at how does the Unity engine work and how do

we get actual 3D models onto the screen?

And we put together a very simple "Flappy Bird" esque game so

that we could sort of recycle prior ideas.

Last week, we looked at "Dread 50," which was sort of a Dreadhall's horror

inspired game where we got to look at lighting

and how to actually transition between scenes and use some basic UI in Unity.

And today, we'll be talking about how to create a game similar to this,

although much simpler.

Today is mostly just a tech demo more than anything else.

But this is a screenshot of the actual game "Portal."

And as you can see, they do a lot of really cool fancy things.

They have a portal on sort of a slope, they

have another portal coming out of the front wall over back there.

There are different colors so you can differentiate between left and right,

orange and blue.

They have sort of this object here on the side,

and I believe that's to shoot cubes out, which this here

is a cube which you can then grab with your gun

and then shoot it through portals and see it come in and out of portals,

which is pretty cool.

And we'll talk today about how to create a simple version of this, primarily

just the aspect of how do I create a portal that looks out of another scene

and see it updating in real time?

And how do I teleport and get back and forth between the portals

and carry a weapon and then shoot a ray that will actually place a portal where

I want to in the game world?

So today, some of the topics we'll talk about.

So one, holding a weapon.

So we've used a first person controller, and this

is a very easy and simple thing to do.

But it helps illustrate what parenting is.

And so we'll talk about that.

Ray casting is the actual shooting out of a ray from your object

to Z direction forward.

So you have an X and a Y, which are sort of the angle at which you're

moving around.

But then you have Z, which if you're using the forward vector

from your character, it's going to be forward in the z-axis

wherever you're looking effectively.

And so that allows us to cast a ray, in that sense, which just means shoot

a straight line, an invisible straight line from that point,

and wherever that point intersects with an object,

we can get some information about that and then do

whatever work we need to do.

In this case, take a portal prefab and just affix it to the wall, basically.

Rotate it from its default position, and then just

put it flat up against the wall.

Texture masking is how we're going to achieve this portal effect, right?

Because when we create what's called a render texture in Unity, which here's

the third bullet, a render texture just means a texture

that we're rendering to with a camera.

So rather than have a texture be an asset in your game, in your hierarchy

with something that you made in Photoshop,

you can actually dynamically create it at runtime

with what the camera is seeing.

And Unity gives this to you for free very easily

with what's called a render texture, which is just another asset type.

And then texture masking is effectively the same thing

as stenciling where we can choose certain pixels of an object to delete.

In this case, we create a texture that's white in the center and then black

around the edges in an elliptical shape.

And what that allows us to do is tell it with a simple shader,

don't render these pixels when you actually render the render texture,

just render the ones in the middle.

And so, that's how we achieve an ellipse, just by effectively

discarding the pixels in the outer rim.

Decals is an idea in 3D games where a decal is just something

that you affix a texture or some object that you affixed to a surface.

In this case, we'll be using decals to act as our portal.

So our portals are actually just going to be decals.

They're just meshes with a render texture affixed to them.

And then all we need to do is just slap them onto a wall whenever we shoot it,

and we get a ray that intersects with the wall.

And that will have the effect of actually making

it look like we're putting a portal on a wall, when in reality, we're

just taking a mesh and we're kind of just like slapping it onto a wall.

Some other examples of decals that you've probably seen in other games

are, for example, bullet holes, which use the same principle.

Teleporting is very easy, although the FPS controller sort

of complicates things a little bit.

So we'll talk about how and about sort of solving the problem of teleporting

in a way that makes sense.

It's usually just as simple as setting something's transforms position

to another transforms position, setting the rotation

to the transforms rotation.

But the FPS controller cashes its rotation data,

so in order to that teleport cleanly you sort of

have to override some default behavior.

And lastly, we'll take a look at some new tools

that Unity has introduced with 2018 0.1 Pro Builder and Pro

Grids, which allow you to actually model geometry in the scene.

And this is what the assignment is going to be focused on.

Because going forward, I foresee it being a major part of modern unity

development and or prototyping.

The ability to model your scene in Unity without needing a third party program

heavily optimizes the actual creation process

and allows you to do easy, what's called,

"gray boxing," meaning create a level in your game engine and then prototype it,

test it, make sure that it's actually game playable right off the bat.

That's called "gray boxing."

But first, let's get a demo.

So does anybody want to come up here and play my implementation of "Portal?"

So James is landlocked.

All right James, you're not landlocked.

Let's go.

All right, so I'm going to go ahead and set that up.

And so disclaimer, there's actually a bug in this

as well, so I'm curious to see if you can spot what the bug is.

Go ahead and hit play as soon as you're ready.

And then the mouse on the right will be your angle your portal.

So we see here I have a character with a portal gun created.

So James, if you shoot a wall with the left mouse, that will create a portal.

And then if use the right mouse--

so that's one other bug.

So let's go ahead and restart the program, actually.

So that's one bug.

And so, if we avoid stepping into a portal that's there--

and this this could be fixed in a couple of ways.

So now you have two portals basically created.

Do you see what's wrong with the portal as it is here, both of these portals

actually?

Oh actually, no, I'm sorry, these portals are actually completely right.

But walk through them.

And I will show you--

OK, so you can see it works pretty well, right?

You can not only see your character rendering completely or moving

in real time when the other texture, but you can jump through them

or walk through them.

You can jump with spacebar if you want, and that'll

teleport you throughout the other end so you

see from the perspective of the other portal.

But if we try shooting one of the other walls

for instance, like one of these white walls,

you can see something weird happens with this particular wall.

Anything strike you as odd about that portal?

Anybody?

It's upside down.

And so if you walk through it though, it works perfectly fine.

Now the reason that it's upside down, I spent probably like 10, 15 hours

trying to figure out why this is, it's in a state

of what's called "gimbal lock."

So this prefab right here, there's three axis of rotation in 3D space.

And if you perform a rotation in some odd way,

there are these things called oiler angles,

which are your angles of rotation about the x,y and z-axis.

And you can sort of think of them as sort

of being able to rotate interdependently.

But there is a situation in which you can--

for some reason, Unity's internal representation of a rotation

can get messed up by manipulating these angles.

And so, you can actually lock two axes together such

that rotating-- like for example, in this case, it's Z and Y,

they both rotate each other.

And so you're unable to get, in this particular case, the portal to rotate

about the axis that lets it look like its right side up based