You know how there are programs that you can use to pose CGI people models for reference? Are there any that let you paint onto them? I've been thinking it would be handy for keeping the fur patterns on some of my characters consistent from one shot to the next as the camera angle and pose changes.
Link
dogpencil
Blender has a "paint directly on a 3d model" feature, but you'd have to source your own (or create your own) rigged character model to paint on and pose.
Zbrush I think does it too I think, with similar caveats
I don't know any apps made expressly for this purpose but honestly I've never looked...