[Mesa-dev] [PATCH RFC v1] i965: Implement CopyTexSubImage2D via BLORP (and use it by default).

[Paul Berry]

On 21 January 2013 00:55, Eric Anholt <eric at anholt.net> wrote:

> Paul Berry <stereotype441 at gmail.com> writes:
>
> > On 19 January 2013 11:06, Kenneth Graunke <kenneth at whitecape.org> wrote:
> >> +   //intel_renderbuffer_set_needs_downsample(dst_irb);
> >>
> >
> > I'm ok leaving this out--at the moment there's no way this code can be
> hit
> > for a multisampled destination image.  However, if we ever get around to
> > implementing the GLES extension EXT_multisampled_render_to_texture, we'll
> > have to have a hard think about what the correct behaviour should be.
> > Perhaps we should put a comment here saying something like:
> >
> > /* Note: there is no need to call
> intel_renderbuffer_set_needs_downsample()
> > on the destination buffer, since automatic downsample is only needed for
> > multisampled window system framebuffers, which are not allowed as
> > destinations for CopyTexSubImage.  However, this will need to be
> revisited
> > if we ever support EXT_multisampled_render_to_texture. */
>
> Isn't that extension all about multisampled user framebuffers, not
> window system framebuffers?
>

It's about multisampled textures that need to get automatically downsampled
in the same way that multisampled window system framebuffers do.  That's
why we'll need to revisit the relationship between CopyTexSubImage and
intel_renderbuffer_set_needs_downsample() when we implement it, because
we'll need to translate the renderbuffer's needs_downsample flag into a
more general texture needs_downsample flag, and make sure it gets set at
the proper times.
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