[Mesa-dev] [PATCH 3/5] mesa/meta: Add support for storing the current read buffer

[Neil Roberts]

Is this patch necessary? I think the read buffer is part of the
framebuffer state so any meta function that binds its own framebuffer
won't need to save the read buffer, right? This is the case for
_mesa_meta_CopyImageSubData_uncompressed which binds both a read and
write FBO so I think it shouldn't be needed at least for this patch
series. Presumably the _mesa_meta_begin there can just pass 0 for the
state to save because hardly any state affects glBlitFramebuffer and it
is binding its own framebuffers.

If we do use this patch then I think MESA_META_READ_BUFFER would have to
be removed from the state that is saved in
copytexsubimage_using_blit_framebuffer because in that case we do want
to read from whatever the application has chosen for the read buffer.
There seems to be a number of other meta functions that explicitly
disable MESA_META_DRAW_BUFFER even though they bind their own
framebuffer. Maybe this is just for performance, but arguably these
functions should also disable saving MESA_META_READ_BUFFER.

Regards,
- Neil