Are Vertex programms only for NVidia Cards, or do they also bring some performance advances for other grafic cards?
Juergen
its an extension called GL_NV_vertex_program
means you can USE this ext only on nvidia cards.
programable vertex pipelines are supported on gf3 and gf4 and radeon8500 that means there you get boost
on the radeon you have to use GL_EXT_vertex_shader, not supported by nvidia
Direct3d has generic vertex shader functionality - in that a vertex shader will work on any driver that exposes a vertex shader interface…even though the shader may not be implemented in hardware (all transforms could be done on the cpu).
OpenGL extensions give you more direct communication with the hardware - the end result is usually better performance than direct3d as well as more functionality (eg. register combiners have more flexibility than d3d pixel shaders). The downside is that they’re generally vendor specific.
I don’t think it would be much effort to emulate vertex programs on any other hardware, you’d just be performing double the transformations (the main ones in software, then pass the result on to an ortho projection in hardware).