GL_ARB_fragment_program & NV20

NV20 support GL_NV_register_combiners & GL_NV_texture_shader.
But why it doesn’t support GL_ARB_fragment_program?
Who can give me a detailed answer?

Thanks very much!

[This message has been edited by maplexp (edited 08-19-2003).]

Because the hardware isn’t capable of supporting the whole of ARB_Fragment_Program.

They could support ARB_FP with very simple programs, but then it complicates matters knowing what kinds of ARB_FP’s would fit and work on NV20 architecture, so instead they simply dont support it.

Basically, GL_ARB_fragment_program assumes floating point operation, which the NV20 does not support.

… Not to mention the required minimum of 72 program instructions, 24 texture fetches, or 4 texture indirections.

– Tom

Thank you very much!