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Am 2015-02-12 um 08:45 schrieb Stefan Dösinger:
Am 2015-02-11 um 23:56 schrieb Matteo Bruni:
It's probably hard to measure and not going to really matter in practice but toggling the depth clamping (where supported) might be slightly faster than updating the projection matrix.
I'll try to patch my drawprim overhead tester to test this.
Fwiw, I cannot see any performance difference between ARB_depth_clamp and the projection matrix approach in my modified test program.
What I did: Set a POSITIONT vertex
while(running) { for(i = 0; i < 1000; i++) { set_rs(ZENABLE, TRUE); draw(); set_rs(ZENABLE, FALSE); draw(); set_rs(ZENABLE, TRUE); draw(); set_rs(ZENABLE, FALSE); draw(); set_rs(ZENABLE, TRUE); draw(); set_rs(ZENABLE, FALSE); draw(); } present(); }
I.e., I hit the worst case for the new approach. With ARB_depth_clamp this test program runs at 89.5 fps, with matrices at 89.2. There seems to be a general up and down of +/- 5 fps. Interestingly windows runs this test program at 58 fps.
I tested this on Nvidia. I can also test it on r600g if desired, but I don't really expect it to matter.