[cairo] new trapezoid code in glitz

[Carl Worth]

On Thu, 27 Jan 2005 13:21:43 +0100, David Reveman wrote:
> fixed size texture. By using linear texture filtering this allows us to
> render perfectly anti-aliased geometry on a wide range of hardware.

This sounds quite interesting.

> However, non-intersecting trapezoids are always going to be faster. I'd
> like to see a trapezoid attribute in cairo that will indicate to the
> backends that the trapezoids are not intersecting. I shouldn't be too
> hard for the tessellator to keep track of this, right? 

What do you mean by "non-intersecting trapezoids"? The set of
trapezoids that fall out of the tessellator are disjoint by
definition.

> How about making the tessellator snap intersection points to the pixel
> grid and produce non-intersecting trapezoids if the tolerance is greater
> than half a device unit?

Oh, is it that you actually want to know if any pixels are
intersected by more than one trapezoid? In that case, something like
the above might very well work.

> This will of course be a lot slower than the current glitz
> backend but the output quality will instead be perfect, and I think
> that's a lot more useful. If someone thinks this is a bad idea let me
> know.

I've always liked the idea of starting with correct output and adding
performance from there.

-Carl

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