Sorry, but I just can't see that in the driver. And there's no ALPHA_DST_SEL bit, at least not in the mach64 reg file I have...On Thu, Mar 03, 2005 at 05:45:15PM +0100, Roland Scheidegger wrote:
Brian Paul wrote:
Roland Scheidegger wrote:
here's a patch which mainly does 3 things: - convert sis, mach64, and radeon to spantmp2. The sis and mach64 drivers got a slight change, previously you could not read back alpha values (always 0xff) and I don't think there was a good reason for that?
IIRC, the mach64 doesn't support destination alpha planes. OpenGL requires that reads of absent alpha planes returns 1.0. I don't know
if the SiS chip is the same.
Are you sure? At least the driver handles things like GL_DST_ALPHA blend
factors, wouldn't you get awfully bogus results if it wouldn't support destination alpha planes in that case?
Like I said before only the RGB components are blended. You can choose to write 0, 1, As, 1-As, Ad or 1-Ad to the destination alpha ([EMAIL PROTECTED] register). Currently the driver seems to write 0. It would probably be a better idea to write 1 instead.
Regardless if it can actually blend alpha values or not, there would be some half-way useful alpha values probably in the buffer.
Roland
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