[cairo] new trapezoid code in glitz

[David Reveman]

On Thu, 2005-01-27 at 11:08 -0500, Carl Worth wrote:
> 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? 

of course, thanks.

> In that case, something like
> the above might very well work.

good, I think that would be very useful.

> 
> > 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.
> 

-David