On Wed, Sep 19, 2012 at 01:27:55PM -0700, Kenneth Graunke wrote:
> A game we're working with leaves scissoring enabled, but frequently sets
> the scissor rectangle to the size of the whole screen. In that case,
> scissoring has no effect, so it's safe to go ahead with a fast clear.
>
> Chad believe this should help with Oliver McFadden's "Dante" as well.
>
> v2/Chad: Use the drawbuffer dimensions rather than the miptree slice
> dimensions. The miptree slice may be slightly larger due to alignment
> restrictions.
>
> Signed-off-by: Kenneth Graunke <kenn...@whitecape.org>
> Signed-off-by: Chad Versace <chad.vers...@linux.intel.com>
> Cc: Oliver McFadden <oliver.mcfad...@linux.intel.com>
Reviewed-by: Oliver McFadden <oliver.mcfad...@linux.intel.com>
Tested-by: Oliver McFadden <oliver.mcfad...@linux.intel.com>
> ---
> src/mesa/drivers/dri/i965/brw_clear.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_clear.c
> b/src/mesa/drivers/dri/i965/brw_clear.c
> index c3c75df..625cc85 100644
> --- a/src/mesa/drivers/dri/i965/brw_clear.c
> +++ b/src/mesa/drivers/dri/i965/brw_clear.c
> @@ -77,6 +77,18 @@ debug_mask(const char *name, GLbitfield mask)
> }
>
> /**
> + * Returns true if the scissor is a noop (cuts out nothing).
> + */
> +static bool
> +noop_scissor(struct gl_context *ctx, struct gl_framebuffer *fb)
> +{
> + return ctx->Scissor.X <= 0 &&
> + ctx->Scissor.Y <= 0 &&
> + ctx->Scissor.Width >= fb->Width &&
> + ctx->Scissor.Height >= fb->Height;
> +}
> +
> +/**
> * Implements fast depth clears on gen6+.
> *
> * Fast clears basically work by setting a flag in each of the subspans
> @@ -110,7 +122,7 @@ brw_fast_clear_depth(struct gl_context *ctx)
> * a previous clear had happened at a different clear value and resolve it
> * first.
> */
> - if (ctx->Scissor.Enabled) {
> + if (ctx->Scissor.Enabled && !noop_scissor(ctx, fb)) {
> perf_debug("Failed to fast clear depth due to scissor being enabled. "
> "Possible 5%% performance win if avoided.\n");
> return false;
> --
> 1.7.11.4
>
--
Oliver McFadden.
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