On Thu, 4 Apr 2002 01:56:22 +0100 José Fonseca <[EMAIL PROTECTED]> wrote:
> On 2002.04.03 23:50 Sergey V. Udaltsov wrote: > > > He!He!.. you missed!! It's a mix of variant 1 and 2..! :) > > Cool. At least 1+2 is the answer (call it 5). Thanks. > > > > > As Leif previously said is his reply, it can be done in hardware by > > > messing the colors of the vertex to incorporate the fog (as software > > Mesa > > > used to do in 3.x) but it's non-conformant to the OpenGL spec. > > What's the difference in Mesa 4? Is it better? Can it be done in HW? > > Will this non-conformance cause visible problems on display? > > In Mesa 3.x when fog was enabled the vertex colors were changed so that > the further away is the vertex more its color is nearer to the fog > background color. Since the colors are interpolated in the triangle this > gave the impression of fog. > > But the OpenGL spec says that the fog color is calculated on a _pixel_ > basis and not on a _vertex_ basis. Indeed the result is different, > especially in long polygons that span from the front way to the back. Actually I think it gives you scope to do either. The issue with adding fog into the vertex colors is what happens when texturing is turned on - the vertex color may not even contribute to the color of the generated fragments. Keith _______________________________________________ Dri-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/dri-devel
