View Full Version : ARB_fragment_program: number of ALU instructions

11-30-2002, 01:11 AM
Just a quick question. My 9700 reports that it supports 64 ALU instructions, is that per indirection or in total ? With the ATI_fragment_shader extension you had 8 instructions per-pass ( indirection in ARB_fp terms ) and the glGet(..) function reported 8.

11-30-2002, 06:59 AM
ATI_fragment_shader uses the semi-programmable mode of the Radeon 8500, which is somewhat like two passes over a fixed set of execution hardware.

The R300 support a fully orthogonal assembly language, where instructions really mean instructions, and there's no first or second pass (phase) to worry about.

Thus, the limits reported should be the overall limits for a single shader.

11-30-2002, 07:54 AM
Thanks, that does seem logical. I wrote my first fragment program yesterday ( 35 instructions ) and it went pretty smoothly. I still trying to get used to having vertex program flexibility at the fragment level.