Kenneth Graunke <kenn...@whitecape.org> 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.
*/
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