Around 11 o'clock on Dec 9, Juliusz Chroboczek wrote:
> But then I'll need to do all core rendering twice, once to the pixmap,
> once to the alpha channel, right? Is it worth the hassle, or shall I
> fall back to render rendering when there's an alpha channel?
I'm afraid it would be worth the hassle. There are several reasons why
accelerated drawing hasn't happened yet:
1) The spec isn't quite complete, we need to figure out how
gradients and shading fit in.
2) The precise sematics for filling trapezoids haven't been carefully
written down and verified.
3) We have no test suite to check the current software implementation
let alone hardware accelerated implementations
4) There aren't comprehensive performance tests for the whole
extension.
Carl Worth and I are working on building a test suite for the parts of the
extension which are stable; I've got half a dozen students working on the
basic extension while Carl is building tests for trapezoids. The test
suite development should point out many inconsistencies and inaccuracies
in the specification which should make that a lot more solid. Carl has
already found a small issue with trapezoid rendering which needs some
study.
Figuring out how to specify gradients and shading seems like something we
need to get a handle on so that the specification can be finalized. My
current thoughts on this matter are that somehow shading, gradients and
image transformations are all related; each of these relate a point in the
destination with some function operating on a collection of colors. I
think it would be possible to relate the basic projective image
transformation somehow to operations for shading trapezoids and performing
gradients across fills.
Keith Packard XFree86 Core Team HP Cambridge Research Lab
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