[Mesa-dev] [PATCH 2/2] radeonsi: fix gl_ClipDistance and gl_ClipVertex for points

[Nicolai Hähnle]

From: Nicolai Hähnle <nicolai.haehnle at amd.com>

The clipper hardware doesn't consider points as primitives that can be
clipped. Simply setting the corresponding cull bits works, and should not
have an adverse effect on other primitive types according to the hardware
team.
---
 src/gallium/drivers/radeonsi/si_state.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/gallium/drivers/radeonsi/si_state.c b/src/gallium/drivers/radeonsi/si_state.c
index d86b99f..f6f61a6 100644
--- a/src/gallium/drivers/radeonsi/si_state.c
+++ b/src/gallium/drivers/radeonsi/si_state.c
@@ -671,34 +671,42 @@ static void si_emit_clip_regs(struct si_context *sctx, struct r600_atom *atom)
 	unsigned total_mask;
 	bool misc_vec_ena;
 
 	if (vs->key.opt.hw_vs.clip_disable) {
 		assert(!info->culldist_writemask);
 		clipdist_mask = 0;
 		culldist_mask = 0;
 	}
 	total_mask = clipdist_mask | culldist_mask;
 
+	/* Clip distances on points have no effect, so need to be implemented
+	 * as cull distances. This applies for the clipvertex case as well.
+	 *
+	 * Setting this for primitives other than points should have no adverse
+	 * effects.
+	 */
+	clipdist_mask &= rs->clip_plane_enable;
+	culldist_mask |= clipdist_mask;
+
 	misc_vec_ena = info->writes_psize || info->writes_edgeflag ||
 		       info->writes_layer || info->writes_viewport_index;
 
 	radeon_set_context_reg(cs, R_02881C_PA_CL_VS_OUT_CNTL,
 		S_02881C_USE_VTX_POINT_SIZE(info->writes_psize) |
 		S_02881C_USE_VTX_EDGE_FLAG(info->writes_edgeflag) |
 		S_02881C_USE_VTX_RENDER_TARGET_INDX(info->writes_layer) |
 	        S_02881C_USE_VTX_VIEWPORT_INDX(info->writes_viewport_index) |
 		S_02881C_VS_OUT_CCDIST0_VEC_ENA((total_mask & 0x0F) != 0) |
 		S_02881C_VS_OUT_CCDIST1_VEC_ENA((total_mask & 0xF0) != 0) |
 		S_02881C_VS_OUT_MISC_VEC_ENA(misc_vec_ena) |
 		S_02881C_VS_OUT_MISC_SIDE_BUS_ENA(misc_vec_ena) |
-		(rs->clip_plane_enable &
-		 clipdist_mask) | (culldist_mask << 8));
+		clipdist_mask | (culldist_mask << 8));
 	radeon_set_context_reg(cs, R_028810_PA_CL_CLIP_CNTL,
 		rs->pa_cl_clip_cntl |
 		ucp_mask |
 		S_028810_CLIP_DISABLE(window_space));
 
 	/* reuse needs to be set off if we write oViewport */
 	radeon_set_context_reg(cs, R_028AB4_VGT_REUSE_OFF,
 			       S_028AB4_REUSE_OFF(info->writes_viewport_index));
 }
 
-- 
2.7.4