Create fast a texture with overdraw information

Hi guys,

I need to create a texture that contains the overdraw after a certain amount of draw primitives. I need this to work as fast as possible on the last NVidia cards (It’s not only for debug display). The image will be further processed in GLSL.

I saw that I can use GL_NV_copy_depth_to_color, but is there a way to achieve the same result without coping.
What about accumulation buffer? Should I try it? Is it still so slow?

I will work with really big texture, so I would like to avoid the coping.


Contains the overdraw? As in “how many primitives wrote on this pixel” ? If so, do additive-blending into a floating-point framebuffer.

Thanks Ilian!
You are absolutely right. That should work!