I would like to implement shadow mapping for point light by rendering the depth in a cubemap. I don't use geometry shader to render it in one time. I have two 7900GTX in SLi.
The problem is that when I attach a depth render buffer, one for each FBO, each one attached to one face, the framerate is very low. However, when I do not attach the depth render buffer, the framerate is high.
Do you know where is the problem?
Do attaching a depth map to a FBO is supported only by G80 processor? Even with a GF7900 I need to render my point light as 6 spot?