draw: implement distance culling

Works similarly to clip distance. If the cull distance is negative
for all vertices against a specific plane then the primitive
is culled.

Signed-off-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: Jose Fonseca <jfonseca@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/gallium/auxiliary/draw/draw_gs.c b/src/gallium/auxiliary/draw/draw_gs.c
index 74c6279..b762dd6 100644
--- a/src/gallium/auxiliary/draw/draw_gs.c
+++ b/src/gallium/auxiliary/draw/draw_gs.c
@@ -797,6 +797,10 @@ draw_create_geometry_shader(struct draw_context *draw,
          else
             gs->clipdistance_output[1] = i;
       }
+      if (gs->info.output_semantic_name[i] == TGSI_SEMANTIC_CULLDIST) {
+         debug_assert(gs->info.output_semantic_index[i] < Elements(gs->culldistance_output));
+         gs->culldistance_output[gs->info.output_semantic_index[i]] = i;
+      }
    }
 
    gs->machine = draw->gs.tgsi.machine;