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, 17 insertions, 0 deletions

diff --git a/src/gallium/auxiliary/draw/draw_context.c b/src/gallium/auxiliary/draw/draw_context.c
index 81b3068553..0dbddb4511 100644
--- a/src/gallium/auxiliary/draw/draw_context.c
+++ b/src/gallium/auxiliary/draw/draw_context.c
@@ -752,6 +752,23 @@ draw_current_shader_num_written_clipdistances(const struct draw_context *draw)
    return draw->vs.vertex_shader->info.num_written_clipdistance;
 }
 
+
+uint
+draw_current_shader_culldistance_output(const struct draw_context *draw, int index)
+{
+   if (draw->gs.geometry_shader)
+      return draw->gs.geometry_shader->culldistance_output[index];
+   return draw->vs.vertex_shader->culldistance_output[index];
+}
+
+uint
+draw_current_shader_num_written_culldistances(const struct draw_context *draw)
+{
+   if (draw->gs.geometry_shader)
+      return draw->gs.geometry_shader->info.num_written_culldistance;
+   return draw->vs.vertex_shader->info.num_written_culldistance;
+}
+
 /**
  * Return a pointer/handle for a driver/CSO rasterizer object which
  * disabled culling, stippling, unfilled tris, etc.