I have a sphere (call if a planet if you wish) and I would like to displace the vertexes using a height map. This height map however is a cube map texture generated on the GPU using shaders. It does not change, it is simply generated once.
I basically want the equivalent of sampling the cube map in the vertex shader and displacing my vertexes accordingly. Texture samples in the vertex shader are not generally supported though, and I really should only do the sampling once per vertex, not every frame anyway.
I tried to get the ram image, but I got a 0 pointer which I guess indicates it could not get a ram image. Thus I tried makeRamImage which seems to work (at least returns a pointer I might be able use for something) but causes a Segmentation Fault to occur a bit later.
So how can I sample a cube map generated on the GPU on the CPU?
Thanks. It seems to have worked. Now, any tips for converting a vector to cube map u,v,w? I know how to get which face it is (+x,-x,-y…) and some coordinates on that face, but how do I know which face is which index (0-5) and which way u and v go (to get the right rotation and not mirrored). Guess and check?