Material ID Pass with Knockout?


Is there anyway to render a material ID pass with a knockout of a texture. For example I am rendering a car. The paint is a blend material. Within this blend mtl there is a shader that has a transparency map, so the carpaint can can have decals on top of it. Now I want to render a matte pass for the paint that has the decals knocked out of it. I know I can do this in a render layer, but Id really like to know how to do it with just a render element.


I work with cars aswell. We tend to have the decals as a seperated objects and render them seperatelyand drop them on top in post. This way they can easily be leveled off as they often become less visible if just rendered together. PLus we often do various grades of cars so we can easily switch them reducing the amount of renders.You could use the black and white map you are using for the blend into a surface shader and use that to subtract from your carpaint mask? Im not too sure about material ID’s but maybe that helps


I actually ended up plugging the outcolor of a surface shader,which uses the matte texture, into the vrayColorId of each material’s shading group. Then the material ID pass renders with the decal matte built in.


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