[Mesa-dev] [PATCH] i965: Set address rounding bits for GL_NEAREST filtering as well.

[Jordan Justen]

On 2016-03-17 01:04:27, Kenneth Graunke wrote:
> Yuanhan Liu decided these were useful for linear filtering in
> commit 76669381 (circa 2011).  Prior to that, we never set them;
> it seems he tried to preserve that behavior for nearest filtering.
> 
> It turns out they're useful for nearest filtering, too: setting
> these fixes the following dEQP-GLES3 tests:
> 
> functional.fbo.blit.rect.nearest_consistency_mag
> functional.fbo.blit.rect.nearest_consistency_mag_reverse_src_x
> functional.fbo.blit.rect.nearest_consistency_mag_reverse_src_y
> functional.fbo.blit.rect.nearest_consistency_mag_reverse_dst_x
> functional.fbo.blit.rect.nearest_consistency_mag_reverse_dst_y
> functional.fbo.blit.rect.nearest_consistency_mag_reverse_src_dst_x
> functional.fbo.blit.rect.nearest_consistency_mag_reverse_src_dst_y
> functional.fbo.blit.rect.nearest_consistency_min
> functional.fbo.blit.rect.nearest_consistency_min_reverse_src_x
> functional.fbo.blit.rect.nearest_consistency_min_reverse_src_y
> functional.fbo.blit.rect.nearest_consistency_min_reverse_dst_x
> functional.fbo.blit.rect.nearest_consistency_min_reverse_dst_y
> functional.fbo.blit.rect.nearest_consistency_min_reverse_src_dst_x
> functional.fbo.blit.rect.nearest_consistency_min_reverse_src_dst_y
> functional.fbo.blit.rect.nearest_consistency_out_of_bounds_mag
> functional.fbo.blit.rect.nearest_consistency_out_of_bounds_mag_reverse_src_x
> functional.fbo.blit.rect.nearest_consistency_out_of_bounds_mag_reverse_src_y
> functional.fbo.blit.rect.nearest_consistency_out_of_bounds_mag_reverse_dst_x
> functional.fbo.blit.rect.nearest_consistency_out_of_bounds_mag_reverse_dst_y
> functional.fbo.blit.rect.nearest_consistency_out_of_bounds_mag_reverse_src_dst_x
> functional.fbo.blit.rect.nearest_consistency_out_of_bounds_mag_reverse_src_dst_y
> functional.fbo.blit.rect.nearest_consistency_out_of_bounds_min
> functional.fbo.blit.rect.nearest_consistency_out_of_bounds_min_reverse_src_x
> functional.fbo.blit.rect.nearest_consistency_out_of_bounds_min_reverse_src_y
> functional.fbo.blit.rect.nearest_consistency_out_of_bounds_min_reverse_dst_x
> functional.fbo.blit.rect.nearest_consistency_out_of_bounds_min_reverse_dst_y
> functional.fbo.blit.rect.nearest_consistency_out_of_bounds_min_reverse_src_dst_x
> functional.fbo.blit.rect.nearest_consistency_out_of_bounds_min_reverse_src_dst_y
> 
> Apparently, BLORP has always set these bits unconditionally.
> 
> However, setting them unconditionally appears to regress tests using
> texture projection, 3D samplers, integer formats, and vertex shaders,
> all in combination, such as:
> 
> functional.shaders.texture_functions.textureprojlod.isampler3d_vertex
> 
> Setting them on Gen4-5 appears to regress Piglit's
> tests/spec/arb_sampler_objects/framebufferblit.
> 
> Honestly, it looks like the real problem here is a lack of precision.
> I'm just hacking around problems here (as embarassing as it is).
> 
> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> ---
>  src/mesa/drivers/dri/i965/brw_sampler_state.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_sampler_state.c b/src/mesa/drivers/dri/i965/brw_sampler_state.c
> index c20a028..d53cb5d 100644
> --- a/src/mesa/drivers/dri/i965/brw_sampler_state.c
> +++ b/src/mesa/drivers/dri/i965/brw_sampler_state.c
> @@ -436,14 +436,17 @@ brw_update_sampler_state(struct brw_context *brw,
>        }
>     }
>  
> -   /* Set address rounding bits if not using nearest filtering. */
> +   /* Set address rounding bits.  The conditions are empirically
> +    * derived in order to pass test cases.
> +    */
> +   bool round_nearest = brw->gen >= 6 && target != GL_TEXTURE_3D;
>     unsigned address_rounding = 0;
> -   if (min_filter != BRW_MAPFILTER_NEAREST) {
> +   if (min_filter != BRW_MAPFILTER_NEAREST || round_nearest) {

How about folding the min_filter != BRW_MAPFILTER_NEAREST test into
round_nearest?

Reviewed-by: Jordan Justen <jordan.l.justen at intel.com>

>        address_rounding |= BRW_ADDRESS_ROUNDING_ENABLE_U_MIN |
>                            BRW_ADDRESS_ROUNDING_ENABLE_V_MIN |
>                            BRW_ADDRESS_ROUNDING_ENABLE_R_MIN;
>     }
> -   if (mag_filter != BRW_MAPFILTER_NEAREST) {
> +   if (mag_filter != BRW_MAPFILTER_NEAREST || round_nearest) {
>        address_rounding |= BRW_ADDRESS_ROUNDING_ENABLE_U_MAG |
>                            BRW_ADDRESS_ROUNDING_ENABLE_V_MAG |
>                            BRW_ADDRESS_ROUNDING_ENABLE_R_MAG;
> -- 
> 2.7.3
> 
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