I have searched this topic for very long time and have found basically no information on it.
If we have a 3d model with a uv layout. What is the basic technique for 3d painting on said model with a brush? A brush stroke consists of the brush pixel data/image laid out in succession. So do we project each individual brush image onto the surface of the object? (Although in actuality to do this we would be projecting the object onto the image space instead). I have managed to project textures onto objects before. And projecting each individual brush image definitely seems feasible, but I'm not sure if it's practical from performance standpoint and whether there're better techniques.