I am trying to paint a texture mask based on a certain camera angle. This texture will then be used with Window coordinates in the material nodes. However, in texture paint mode, its only possible to paint based on UV maps. I can set an image as a camera background image, but you can't paint on that.
If I paint in the Image Editor paint mode, then I can only see the single image I'm painting, and not the other things in the viewport I'm painting over, so its no good.
Is there anyway around this?