What is the proper way, to Blending multi base materials.

xxwlzfb

I saw the sharing of the Assassin's Creed Odyssey in GDC. I have a Question about blending multi base materials. Just like this picture.
It layring multi base materials in Substance Painter.


Then import to Game Engine.They used blending Shader to deal with new materials Blending. Like these pictures below.It maybe used vertex color to blending. So Why not blending it in Substance Painter directly.What is the diffenrent of these 2 ways? What is conditions to used them or more properer？

TheGabmeister

xxwlzfb said:

So Why not blending it in Substance Painter directly.What is the diffenrent of these 2 ways? What is conditions to used them or more properer？

1. Blending the materials using vertex color or other parameters is faster in terms of iteration compared to baking unique textures.

2. You have to reuse as much materials and textures as you can in open-world games. Otherwise, you'll hit your performance budget a lot quicker. The workflow above allows the artists to use let's say a trim sheet in different objects rather than one unique object.

xxwlzfb

TheGabmeister said:

xxwlzfb said:

So Why not blending it in Substance Painter directly.What is the diffenrent of these 2 ways? What is conditions to used them or more properer？

1. Blending the materials using vertex color or other parameters is faster in terms of iteration compared to baking unique textures.

2. You have to reuse as much materials and textures as you can in open-world games. Otherwise, you'll hit your performance budget a lot quicker. The workflow above allows the artists to use let's say a trim sheet in different objects rather than one unique object.

Thanks, TheGabmeister.
But, If I had 3 base materials and their has 2K or 4K texture's resolution. I can combined the height/roughness/metallic/ao maps in one texture for each material. So I need preparing 3 base colors, 3 normals, 3 combine texutres. right? It has 9 textures of 2K or 4K. Does it cost more memory cost?

TheGabmeister

xxwlzfb said:

But, If I had 3 base materials and their has 2K or 4K texture's resolution. I can combined the height/roughness/metallic/ao maps in one texture for each material. So I need preparing 3 base colors, 3 normals, 3 combine texutres. right? It has 9 textures of 2K or 4K. Does it cost more memory cost?

My knowledge in the technical aspect of this is somewhat limited, but the way I understand this is that the textures that are unused in a certain material instance are all excluded when building the app. This way, shaders with lots of texture lookups become optimized and the memory cost minimized.

This is just my guess. Other tech artists here might be able to give a more accurate picture of the optimization happening under the hood.

rollin

There is a fundamental difference in blending per-vertex and blending per material. 
In the first case you have a positional knowledge, like "at the bottom of the pillar"
in the other case you just do it for the whole material, no matter where it is applied

And blending materials in-engine doesn't cost (significant) additional memory as long as the input textures are already loaded anyway. This is the whole idea: you get a lot of variations "for free".

The limiting factor is as far as I know the amount of textures you can blend on top of each other as this will eventually hit the limit of the shader model.

But this is engine related. So what do you want to do or where do you want to do it?

xxwlzfb

rollin said:

There is a fundamental difference in blending per-vertex and blending per material. 
In the first case you have a positional knowledge, like "at the bottom of the pillar"
in the other case you just do it for the whole material, no matter where it is applied

And blending materials in-engine doesn't cost (significant) additional memory as long as the input textures are already loaded anyway. This is the whole idea: you get a lot of variations "for free".

The limiting factor is as far as I know the amount of textures you can blend on top of each other as this will eventually hit the limit of the shader model.

But this is engine related. So what do you want to do or where do you want to do it?

Indeed!! Thank u very much!