Ahh juts came to think of it... Rendering a color pass is not nesseserily the thing you want. Your post is a bit vague on what you want.
First: if you want it to recieve shadows from other objects but not it self turn off casts shadows.
Second: if you want it to cast shadows but not recieve any. Now this is a bit trickier someone could suggest a better way to do it
Duplicate your object.
make the duplicate object unseen to the renderer but still casting shadows.
[li]turn of recieve shadows for your other object
Also its possible to make the object not to recieve shadows from itself, but still casting and recieving shadows from others. But then you probably have to do light linking.
There might be a way to do this with shaders, but im no expert on this. Anyone know? Pixho?
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