[Mesa-dev] [PATCH 5/5 v2] i965: Add support for ARB_copy_image

[Neil Roberts]

One case where the memcpy path won't work is if the source and
destination are the same buffer. In that case it tries to map the
texture twice and hits an assert. I think this could be a legitimate use
case if the source and destination rectangles don't overlap. The
extension spec isn't very clear on whether this is allowed but the spec
for GL 4.4 actually mentions blitting between a single buffer and
implies that it's ok if the rectangles don't overlap. Perhaps one way to
solve this would be to check if src_mt==dst_mt and if so it could map
the union of both rectangles as read and write. It would then have to
manually offset the source and destination pointers to the right place.

You might also want to update the commit message as the patch is no
longer restricted to a pitch of at most INT16_MAX.

Regards,
- Neil

Jason Ekstrand <jason at jlekstrand.net> writes:

> This, together with the meta path, provides a almost-complete implemetation
> of ARB_copy_image.  The only case that won't work is if one of the textures
> is compressed and has a pitch greater than INT16_MAX.  I think that's good
> enough to justify turning on the extension.
>
> v2: Add a fallback memcpy path for when the texture is too big for the
>     blitter
>
> Signed-off-by: Jason Ekstrand <jason.ekstrand at intel.com>