Re: More trouble in trapezoid land

Around 20 o'clock on May 23, Carl Worth wrote:

> Would it make sense to do some (perhaps optional) extra work to
> protect against dropouts, (quick bresenham walk around trapezoid
> edges)? As long as we only turn more pixels on and don't turn any off,
> then we don't' violate the "sum to 1" invariant, no?

No.  X polygons "suffer" from the same problem -- the basic requirement is 
that polygons "tile" the surface -- split a disc into 100 triangles and 
each pixel is touched by exactly one of the triangles.

Avoiding dropouts requires a significantly different fill algorithm which 
wouldn't mesh nicely with tesselation.

Keith Packard        XFree86 Core Team        HP Cambridge Research Lab