[cairo] Fwd: Re: [Mesa3d-dev] more glitz points

Bill Spitzak spitzak at d2.com
Thu Apr 22 11:00:52 PDT 2004

On Wednesday 21 April 2004 11:41 pm, David Reveman wrote:
> I also like the radial gradients to contain two ellipses, one inner
> ellipse and one outer ellipse, the gradient transition vector will be
> from the radius of the inner ellipse to the radius of the outer.

I would think just a center point would get most of the variations that are 
wanted and would be *much* simpler. Connecting two ellipses, especially with 
different axis, without producing disconiunities in the area between them, is 
very difficult and mathematically complex.

I believe that arbitrary center positions inside an arbitrary ellipse can be 
achieved with a 4x4 perspective transform of a 1-radius circle about the 
origin. This transform is certainly accessable and quite fast on OpenGL 
shading hardware. I made some demo pictures showing this here:


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     /\_       _|_========___         Bill Spitzak
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