updated 01:15 pm EST, Fri February 23, 2001
id Software's John Carmack returned from Macworld Expo Tokyo and published an update to his .plan with his complete thoughts on NVIDIA's GeForce3. The post is highly technical; if terms like "triangular rasterization dependencies" and "anisotropic filtering" are unknowns to you, then you won't get much value out of Carmack's analysis. "The short answer is that the GeForce 3 is fantastic," says Carmack. "I haven't had such an impression of raising the performance bar since the Voodoo 2 came out, and there are a ton of new features for programmers to play with." Carmack was also seen making comments at Slashdot including those on how much effect AltiVec has had on his speed tests and the differences in speed in Doom III between the 733 MHz G4 and a 1 GHz Pentium III...
We did a ton of testing the last two weeks while we were putting the demo together.
The 733 G4 was not as fast as my 1 ghz PIII in any of the trouble areas.
Apple is doing a lot of good work, but the CPU's just aren't as fast as the x86 ones.
AltiVec can compensate in some cases, because it is way, way easier to program for than SSE, but it takes a very simple batched, computation intensive task for it to pay off in any noticable way. Amdahls law and all that.
We did a couple functions with AltiVec, but they didn't make much difference.
Video encoding and large image processing are two areas that it can pay off, because you may be spending 90%+ of your time in one page of code.
Even then, it takes a special balance to let a G4 come out ahead, because it has less memory bandwidthd than a high end x86 system.