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UE Sampling Color For Indirect Only From One Texture (Vertex Paint)?


I'm using a vertex paint material that blends between 3 textures. However, I've noticed that UE seems to sample only the top diffuse when it comes to injecting color into the lightmass. I tried using layered materials, replacing the GI, using something else than Lerps, but it didn't change anything. Is it simply a limitation on Unreal's part?

I've recreated the problem with a very basic material:

setup01 result01

As you can see, the whole material injects green into the scene and onto the spheres.

setup02 result02

Whether it's a constant3vector or a texture sample, whether it's plugged in the base color directly or passed through a GI replace, it's still the color layered on top that gets sampled.

If anyone knows if it's a limitation of the engine or something I've goofed, please let me know, it'd be super appreciated!


Product Version: UE 4.17
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asked Oct 20 '17 at 01:57 AM in Rendering

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Yep, that is limitation of Light mass. It will ignore vertex color. Situationally, there are workarounds. For example, you can pre-bake vertex color to a texture and use this texture for blending, instead of vertex color, while using GIreplace material expression. GIreplace separates part of your material graph to be used only for lighting calculations.

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answered Oct 20 '17 at 06:53 AM

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avatar image GabBD Oct 20 '17 at 03:04 PM

Alright thanks a lot! :)

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