Let’s add a new Texture Layer effect called “MASKED” or the like. The effect is quite simple. The mask represents a mask (each pixel either 0 or 1), and for each pixel with a value of 1 (completely white), then the layer will override that pixel. No blending, just override or no override.
This behavior would be quite useful for cases where color parameters will be used to drive a color map texture which the material uses to color literally everything. UVs of individual parts just map to different section of that texture, so the shader material can remain dead simple, and we just crank out a new texture as part of COI color parameter changes.
I already have this working with the current Texture Layer effects, but none of them behave the way I’ve described above. None of them are capable of just passing along the exactly specified color to the masked region.