@rollin: he want´s to render his works with a realtime shader so no rendering process there... This is only a solution to his second question and it only works without realtime shaders
If you need the mask, you could just render it twice (why not, it's realtime/fast). Once with the realtime shader, and once where the object has a constant white material with a constant black background.
Hello. Like you, I am excited by real time shaders. The ones around here are particularly nice. I would like to composite some realtime animation sequences but getting the entire finished shot into the viewport is impossible. I was taking screenshots frame by frame and matching the viewport color in the composite but its…