On 06/07/2013 12:58 PM, Eric Anholt wrote:
Kenneth Graunke <[email protected]> writes:
On 06/05/2013 10:14 AM, Eric Anholt wrote:
This gets us support for blitting to attachment types other than
textures.
+ /* Blit to all active draw buffers. We don't do any pre-checking,
+ * because we assume that copying to MRTs is rare, and failure midway
+ * through copying is even more rare. Given that feedback loops in
+ * glFramebufferBlit() are undefined, we can safely fail out after
+ * having partially completed our copies.
The first part of this comment makes sense: yes, it's obviously rare.
The second part I feel could use a little more explanation:
If we fail midway through a blit, we return without clearing
BUFFER_BITS_COLOR from the mask. The caller will fall back to the next
method (i.e. meta_BlitFramebuffer) and use that to blit /all/ RTs - even
ones we already successfully blit. Given that feedback loops in
glFramebufferBlit() are undefined, we can safely fail out after having
partially completed our copies.
Unless there's some kind of blending, it doesn't even seem
undefined...meta should just overwrite the colors again, and everything
will work out.
Better?
/* Blit to all active draw buffers. We don't do any pre-checking,
* because we assume that copying to MRTs is rare, and failure midway
* through copying is even more rare. Even if it was to occur, it's
* safe to let meta start the copy over from scratch, because
* glBlitFramebuffer completely overwrites the destination pixels, and
* results are undefined if any destination pixels have a dependency on
* source pixels.
*/
Yes, I like this better. I'm good with this series now. Thanks!
--Ken
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