So I want to create a sort of dynamic skybox, with a standard cube map as the backround, and quads depicting orbiting planets and other celestial phenomena.
I tried creating a dynamic cube map, and before I succeeded I decided that this approach is really very expensive for what I'm trying to do, as there's only ever going to be maybe ten billboards floating around the sky. Rendering the 6 faces of a cube map over that is overkill I think. Just clearing the 6 faces had a significant impact on my framerate.
What I'd like to do instead, is draw the planets as I normally would draw a quad, but have them:
pass in front or behind each other correctly according to distance,
be in front of the background skybox.
be behind everything else.
Can I do that with certain DepthStencilState settings, or does anyone else have any other ideas?
EDIT: If I make my projection matrix too deep, I'm going to have z-fighting issues with the other components in the scene, therefore I can't just make it 'real' by putting the planets far away.