[Mesa-dev] [PATCH] st/mesa: fix WPOS adjustment

[Christoph Bumiller]

On 16.04.2011 18:50, Christoph Bumiller wrote:
> I hope the new version is correct, the commit message describes why I
> did the first change, and the second change is described in a comment.
>
> Note that the MAD for inversion uses Height - 1 instead of Height.
>
> With this, piglit glsl-arb-fragment-coord-conventions and
> fbo-depth-sample-compare pass on nvc0.
>
> I was assuming that integer pixel centers for size 100 range from 0 to
> 99 and half-integer pixel centers from 0.5 to 99.5.
>
Attached a better version of the patch, potentially saving an
instruction and avoiding precision issues with NEAREST filtering that
made piglit's blending-in-shader fail.

The only other location I found STATE_FB_WPOS_Y_TRANSFORM used was r600
classic, which should also work more correctly now since (at least
according to gallium caps) it uses half-integer pixel center, and for
H=100, 0.5 * -1 + 99 obviously isn't the desired 99.5.

Please review.

Christoph
>
>
> _______________________________________________
> mesa-dev mailing list
> mesa-dev at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/mesa-dev

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/mesa-dev/attachments/20110419/c37f81db/attachment.htm>
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: 0001-mesa-st-mesa-fix-WPOS-adjustment.patch
URL: <http://lists.freedesktop.org/archives/mesa-dev/attachments/20110419/c37f81db/attachment.txt>