NVIDIA GeForce3 Investigation: What NVIDIA didn't tell us

Anti-aliasing performance

GeForce2 and GeForce3 anti-aliasing involve two stages. First, render samples to framebuffer. Second, blend samples and output anti-aliased image to framebuffer.

GeForce2 vs GeForce3 anti-aliasing

During the first stage of GeForce3 multi-sampling, texture bandwidth requirements are not increased from normal rendering. For GeForce2 supersampling, texture bandwidth is increased from normal rendering by a multiple of the degree of anti-aliasing. The 'super' color pixel buffer bandwidth is similar for both GeForce2 and GeForce3, given the same degree of anti-aliasing. Thanks to Z-compression, 'super' depth buffer bandwidth is lesser for GeForce3. During stage two, GeForce2 and GeForce3 consume the same bandwidth when during sampling for the same degree of anti-aliasing. When writing anti-aliased pixels to the framebuffer, GeForce2 additionally writes to the depth buffer. By virtue of its bandwidth advantage, GeForce3 has a sizeable performance gain over GeForce2 (figure 14).

Figure 14: 32-bit anti-aliasing of GeForce2 and GeForce3

Quincunx vs 2- and 4-sample GeForce3 multi-sampling