> This is one area where a binary-only driver lets us down. If 3dfx is
> anything like the g200 hardware, then the function of grDrawTriangle is
> to compute the area of the triangle and hence the slopes of everything
> that must be interpolated across the triangle. It feeds this down to
> the hardware, either all three vertices at once, or perhaps like the
> g200, breaking the triangle up into 2 degenerate quadrilaterals.
>
> In any case, grDrawTriangle almost certainly computes the area, and we
> must also compute the area to do glPolygonOffset. This plus living with
> the inconvenience and unknown mechanism of grDepthBias are the
> compromises ncessary for slope-dependent triangle offset using glide.
That was true for the Voodoo1 where triangle setup was done on the
CPU. That's not true for V2 or later. It can be all calculated on the
hardware, although you can turn on modes where it isn't done that
way.
> I would rate these as regrettable annoyances for the implementor (hi!)
> but otherwise nothing to get in a tizz about.
If you think there are functions missing that would make your life
easier bring them up. There's nothing preventing modifications to Glide
for appropriate reasons. In fact, Glide3 makes extensions easier. So
we could probably get 3dfx to create a "Mesa" extension. We can send
specifications to their developer program and let 3dfx evaluate them.
- |Daryll
_______________________________________________
Mesa-dev maillist - [EMAIL PROTECTED]
http://lists.mesa3d.org/mailman/listinfo/mesa-dev
