Re:War stories: how Crash Bandicoot hacked the original Play...
by xgkickt on Tuesday December 21, 2021 @12:24PM
(#29639629)
>GPUs, even the primitive PSX one, will draw many in a single CPU cycle. I can't find information on the PSX GPU fill rate but I'm sure it's faster than 1 pixel per CPU cycle.
Two pixels per cycle for flat shaded or rectangular primitives. Add another cycle for color interpolation, and another for on-cache texture reads (divided by how many texels are packed into 16 bits). The GPU is clocked around 53MHz so the range of 'many' here is roughly 1 to 4, ignorning that a CPU renderer would probably write two pixels at once. The CPU is also hampered by main memory reads taking a minimum of 5 cycles. Pipelining helps a little but extensive scratchpad use, such as putting the stack on it, was essential.
DOOM PSX did use triangles for the walls, just that they were a single pixel wide.
Two pixels per cycle for flat shaded or rectangular primitives. Add another cycle for color interpolation, and another for on-cache texture reads (divided by how many texels are packed into 16 bits). The GPU is clocked around 53MHz so the range of 'many' here is roughly 1 to 4, ignorning that a CPU renderer would probably write two pixels at once. The CPU is also hampered by main memory reads taking a minimum of 5 cycles. Pipelining helps a little but extensive scratchpad use, such as putting the stack on it, was essential.
DOOM PSX did use triangles for the walls, just that they were a single pixel wide.