On Tuesday, March 1, 2016 9:48:16 AM PST Samuel Iglesias Gonsálvez wrote:
> On Mon, Feb 29, 2016 at 04:33:42PM -0800, Kenneth Graunke wrote:
> > On Friday, February 26, 2016 8:37:33 AM PST Samuel Iglesias Gonsálvez
wrote:
> > > From ARB_viewport_array spec:
> > >
> > > " * On GL3-capable hardware the VIEWPORT_BOUNDS_RANGE should be at least
> > > [-16384, 16383].
> > > * On GL4-capable hardware the VIEWPORT_BOUNDS_RANGE should be at least
> > > [-32768, 32767]."
> > >
> > > Signed-off-by: Samuel Iglesias Gonsálvez <sigles...@igalia.com>
> > > ---
> > > src/mesa/drivers/dri/i965/brw_context.c | 13 +++++++++----
> > > 1 file changed, 9 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/
dri/
> > i965/brw_context.c
> > > index 31b6b2a..1569992 100644
> > > --- a/src/mesa/drivers/dri/i965/brw_context.c
> > > +++ b/src/mesa/drivers/dri/i965/brw_context.c
> > > @@ -687,10 +687,15 @@ brw_initialize_context_constants(struct
brw_context
> > *brw)
> > > ctx->Const.MaxViewports = GEN6_NUM_VIEWPORTS;
> > > ctx->Const.ViewportSubpixelBits = 0;
> > >
> > > - /* Cast to float before negating because MaxViewportWidth is
> > unsigned.
> > > - */
> > > - ctx->Const.ViewportBounds.Min = -(float)ctx-
>Const.MaxViewportWidth;
> > > - ctx->Const.ViewportBounds.Max = ctx->Const.MaxViewportWidth;
> > > + if (brw->intelScreen->driScrnPriv->max_gl_core_version >= 40) {
> > > + ctx->Const.ViewportBounds.Min = -32768;
> > > + ctx->Const.ViewportBounds.Max = 32767;
> > > + } else {
> > > + /* Cast to float before negating because MaxViewportWidth is
> > unsigned.
> > > + */
> > > + ctx->Const.ViewportBounds.Min = -(float)ctx-
> > >Const.MaxViewportWidth;
> > > + ctx->Const.ViewportBounds.Max = ctx->Const.MaxViewportWidth;
> > > + }
> > > }
> > >
> > > /* ARB_gpu_shader5 */
> > >
> >
> > Shouldn't we just support a 32k x 32k viewport? In other words, change
> > MaxViewportWidth/MaxViewportHeight?
> >
>
> Good question. I looked for the HW limitations for Viewport's width
> and heigh but I couldn't find the reference in the PRMs, just that
> it is a 32 bits float. I ran piglit with 32k x 32k viewport in ILK
> and BDW and there is no regressions. But as I didn't know if piglit is
> testing it correctly, I prefered to keep it unchanged. Nevertheless, I
> am open to do this change.
>
> If you agree, I will write a patch that sets MaxViewportWidth and
> MaxViewportHeight to 32k.
>
> SamI tried to look them up too, briefly, and couldn't really find anything either. I think the viewport is basically just an extra rectangle, and that the true limitations come from image (texture/renderbuffer) size restrictions. I suspect we can bump it to 32k with no trouble. I think we should do the following: 1. Fix glInvalidateFramebuffer to use either ctx->Const.ViewportBounds or ctx->Const.MaxViewportWidth/Height instead of MAX_VIEWPORT_WIDTH and MAX_VIEWPORT_HEIGHT (hardcoded #defines for 16384). The spec quote directly above this code makes it pretty obviously wrong. 2. Change Core Mesa to initialize ctx->Const.MaxViewportWidth to 16384. 3. Delete the MAX_VIEWPORT_WIDTH/HEIGHT #defines altogether. 4. Make i965 initialize ctx->Const.MaxViewportWidth/Height to 32768, at least on Gen7+ which support GL 4.0. (some of these changes could probably be squashed together if you like) Thanks for fixing these issues! --Ken
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