We use RGB masks all the time in VFX, don't we?
They are very handy and we can save a lot of extra texture maps combining 4 channels in one single texture map RGB+A.
We use them to mix shaders in look-dev stage, or as IDs for compositing, or maybe as utility passes for things like motion blur o depth.
Let's see how I use RGB masks in my common software: Maya, Clarisse, Mari and Nuke.
- I use a surface shader with a layered texture connected.
- I connect all the shaders that I need to mix to the layered texture.
- Then I use a remapColor node with the RGB mask connected as mask for each one of the shaders.
- We need to indicate which RGB channel we want to use in each remapColor node.
- Then just use the output as mask for the shaders.
- In Clarisse I use a reorder node connected to my RGB mask.
- Just indicate the desired channel in the channel order parameter.
- To convert the RGB channel to alpha just type it in the channel order field.
- You will only need a shuffle adjustment layer and select the required channel.
- You can use a shuffle node and select the channel.
- Or maybe a keyer node and select the channel in the operation parameter. (this will place the channel only in the alpha).