[Mesa-dev] [PATCH 10/17] swrast: Convert color glReadPixels slow path to using MapRenderbuffer.

[Dave Airlie]

> This may be a bit slower than before because we're switching from
> per-format compiled loops in GetRow to
> _mesa_unpack_rgba_block_unpack's loop around a callback to unpack a
> pixel.  The solution there would be to make _mesa_unpack_rgba_block
> fold the span loop into the format handlers.

This one breaks piglit's fragment-center test on r100 for me here, it
looks to render the same image
but the readback is going wrong.

again more FYI, I've no idea why yet.

Dave.