depth component and glCopyTexSubImage2D

Hey, I haven’t found a real good answer for this.
Is there a way to only copy the depth values out
of the frame buffer into a texture as luminance
values using glCopyTexSubImage2D? Maybe by
setting things up properly with glPixelTransferf()?

Look into the SGIX_depth_texture extension.
This will let you use CopyTexSubImage for depth values, and if you then use the texture normally, rather than with SGIX_shadow for example, it will be displayed as luminance.