Hello and welcome to Inside Unreal.
I'm Zack Parrish with Epic Games and I'm joined today by Bill Green, senior artist for Epic
who is going to be talking to us about layered materials in Unreal Engine 4.
Hi, Bill.
Hi, Zak.
So our topic today is layered materials which I understand are a special type of material in UE4.
But, for those who are new, what is just a regular material?
Well, that's the surface definition of an object.
So you can control the color, the specularity, the reflectivity, the bump, the glow - things like that.
Ok, that makes sense. So what is a layered material?
A layered material is basically a material inside of a material.
So if I've created a material over here, that might be red and reflective and have bump. Things like that.
I can create a node out of that and then drag that into my material that I'm making.
Then I can stack them and separate them all out through mass like an RBG channel.
Now why is that significant?
Well, as an artist it's all about control. So you want to be able to just jump in there
and create all of the art you want without being caught up with technical limitations,
just be creative and not worry about it.
Ok, can you show them to us?
Yes, sure.
So here we have two tricycles. They look identical but one uses layered materials and the other one doesn't.
Let's look at the one that doesn't first.
The tricycle is broken up into several different elements. As you can see on the right,
we have each slot with metals and chromes and red paint. Things like that.
But these are defined by polygons so these polygons have chrome materials, they have red paint.
I'll just show you the material of the red paint right now.
Right here is just the material. It's really simple. It's just a color into the base color.
A constant into the metallic, a constant into the roughness, and just your basic normal of your choice.
I'll go ahead and show you just how easy that is to create.
Go to the content browser, right click, select a material. I'll call it "test." And just open it up.
Then what you'll do is right click. You'll create a constant 3 vector for your RGB and double-click that.
Find the color you want. I'll use red. And it's good to go.
Then we'll go ahead and create a constant and plug that into the metallic. I'll duplicate that.
And I'll plug another constant into the roughness.
You can see it's that easy to make a metal paint. Super simple.
I'll save that. And it's good to go.
So you actually specify what materials go where at the polygon level.
Right.
Ok. Now the other one I assume uses layered materials?
Yes. The other one uses a single layered material instead of a separate material element.
Oh yeah, you can see that.
Yes, you can see that it only has one material applied. Inside that material there are layers for things like chrome,
red paint, rubber, and so forth. These are basically separated by texture masking.
Ok. Now can we see the material?
Yes. If I jump inside, you can see right here the nodes that separate the different material layers.
You can also see how we use each channel of texture to control where each one is blended.
Ok, yeah, that has a nice flow to it. I do notice though that on these tricycles,
we're kind of getting the same results with or without layered materials.
So I have to ask, what's so special about the feature?
Well, the tricycles are really just to illustrate the technique.
But if you look back behind them, there are some rockets that Jordan Walker created.
He's our senior technical artist.
The first three, we have basic materials like chrome, aluminum, and copper.
On the fourth rocket, we brought these together into a layered material.
So, in fact, the Unreal Engine logo is actually defined by a texture mask.
We can say that we want the body to be made of copper and the logo to be made of chrome.
Okay, so that's not just a difference in texture like you do in the old school.
We're literally defining where different full materials are being placed?
Right. All through a mask.
Let me just show it to you in wireframe mode, so you can really kind of see what it does.
Oh yeah, you can see that the logo itself is not part of the model at all.
Yes, that's kind of the idea. It's sort of a per-pixel material placement along a surface.
I can see how that adds a lot of flexibility to the art pipeline.
It really does. Regardless of which approach you choose to take, whether it's a single material,
a layered material, or a combination of both, you take control over the look and feel of the object in this new art pipeline.
You can easily make changes at the pixel level and immediately apply them to the entire game.
You can share libraries with your team. So it saves an incredible amount of time.
Very cool.
So that is a look at layered materials in Unreal Engine 4.
Thank you for your time, Bill. We'll see you on the next Inside Unreal.