gl_ClipVertex does this cause Software processing?

OpenGL
1

I just read that R500 and older ATI cards, when you call gl_ClipVertex in the VS this takes vertex processing into software not hardware anymore. Does Nvidia do this to? What about the GF8 series? Does all ATI’s x2000 and x3000 series cards do this?

Thanks

2

ATI has had this issue, but its fixed in later drivers. (Though might depend on your OS)

3

Are you 100% sure? The document I just read was dated 2007 something… Not sure what month, though.

Thanks

4

To be 100% sure perhaps you should write through ATI’s developer program. Those places are the best to take up such issues. They can provided you will all the needed details for your particular hardware.

5

I own an 8800 and using gl_ClipVertex does not cause a software fallback.

6

ATI does not support gl_ClipVertex. The clipping coordinate is computet in the hw with a standard path. I had this issue some time ago and solved it by a little hack which relies on the fact that the nvidia glsl compiler is a hacked cg-compiler:

  #ifdef __GLSL_CG_DATA_TYPES
  gl_ClipVertex = position;
  #endif
7

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