>Before the GPU adds an entry to the raster of pixel colors, it compares the distance of that pixel from the camera with the number in that location in the Z-bu

>Before the GPU adds an entry to the raster of pixel colors, it compares the distance of that pixel from the camera with the number in that location in the Z-buffer. If the current distance is less than the one already found there, it knows that the pixel in question should be overwritten in the main raster and that the Z-buffer raster should be updated with that pixel’s new distance from the camera. Ditto if the Z-buffer contains a null value, indicating no object has yet been drawn at that pixel. But if the current distance is larger than the (non-null) number already found there, the GPU simply moves on without doing anything more Surprisingly not the way 3dfx works. Voodoo 1/2 (no idea about V3, but I wouldnt be surprised) will calculate, texture and gourad shade every single triangle being pushed thru it and only then in the last step decide if it passes Z-buffer/alpha test or not. There is no speed difference between drawing 1000 triangles in random order vs sorted front to back. Speed difference when turning off Z-buffering/alpha is minimal, you only skip the logic deciding between storing or skipping write to framebuffer. There was so much easy optimization left on the floor when first 3dfx cards were being designed! My favorite obligatory 3dfx fall/Nvidia killer mode timeline: Riva 128 (April 1997) to TNT (June 15, 1998) took 14 months, TNT2 (March 15, 1999) 8 month, GF256 (October 11, 1999) 7 months, GF2 (April 26, 2000) 6 months, | 3dfx dies here |, GF3 (February 27, 2001) 9 months, GF4 (February 6, 2002) 12 months, FX (March 2003) 13 months, etc ...