create material mask

[Andygraph3D]

in need create a mask (B/W) about a material in scene but i want make it in one render (render pass)
how is it possible make it ?

[face_off]

I am not 100% sure what you are trying to achieve - but a mix material with mask in the Amount pin is the usual way to do this type of thing.

Paul

[Andygraph3D]

I need to have a mask (B/W) as output render for compositing.
So i ask, is it possible make a rendering "beauty render + mask render" ?

[face_off]

To do this you would need the mask as a material, and output the Beauty and Material Id passes to EXR.

Paul