FrameBuffer to texture

OpenGL OpenGL: Advanced Coding
1

I know that with sgi you can put the framebuffer directly to a texture using the pbuffer. This alows you to bypass the slow copy pixel that travels across the agp bus into processor memory and then back to a texture.

Has anyone read of a way to do this with opengl, opengl extensions, or an nvidia extension?

The reason I want to map the framebuffer to a texture is to so I can do reflextions (or shadows) by rendering an object from a different viewpoint and then mapping that to a texture. Having to go out to processor memory will just kill performance. Any help would be great. Thank!!!

2

AFAIK all glX implementations (IE on Linux) have to provide a pbuffer. Could be wrong though.

NVidia have started optimising their drivers (this from a Geforce FAQ)

Writing to the depth buffer via glDrawPixels is quite slow (though reading the depth buffer via
glReadPixels is moderately fast).

Paul.

3

Tried glCopyTexImage2D?

“The glCopyTexImage2D function copies pixels from the frame buffer into a two-dimensional texture image.”
See http://msdn.microsoft.com/library/default.asp?URL=/library/psdk/opengl/legalgl_62pa.htm

4

Thanks Relic that is EXACTLY what I was looking for.

Sorta sad that it’s a standard gl call and I didn’t remember it. Thanks a ton.