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

[Kenneth Graunke]

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) {
       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