draw: make sure clipdistances work with geometry shaders

we were always fetching the info from the vertex shader, but if
geometry shader is present it should be used as the source of
that info.

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>

src/gallium/auxiliary/draw/draw_cliptest_tmp.h

@@ -111,7 +111,8 @@ static boolean TAG(do_cliptest)( struct pt_post_vs *pvs,
 
          if (flags & DO_CLIP_USER) {
             unsigned ucp_mask = ucp_enable;
-            int num_written_clipdistance = pvs->draw->vs.vertex_shader->info.num_written_clipdistance;
+            int num_written_clipdistance =
+               draw_current_shader_num_written_clipdistances(pvs->draw);
             while (ucp_mask) {
                unsigned plane_idx = ffs(ucp_mask)-1;
                ucp_mask &= ~(1 << plane_idx);

src/gallium/auxiliary/draw/draw_context.c

@@ -737,9 +737,20 @@ draw_current_shader_clipvertex_output(const struct draw_context *draw)
 uint
 draw_current_shader_clipdistance_output(const struct draw_context *draw, int index)
 {
+   if (draw->gs.geometry_shader)
+      return draw->gs.geometry_shader->clipdistance_output[index];
    return draw->vs.clipdistance_output[index];
 }
 
+
+uint
+draw_current_shader_num_written_clipdistances(const struct draw_context *draw)
+{
+   if (draw->gs.geometry_shader)
+      return draw->gs.geometry_shader->info.num_written_clipdistance;
+   return draw->vs.vertex_shader->info.num_written_clipdistance;
+}
+
 /**
  * Return a pointer/handle for a driver/CSO rasterizer object which
  * disabled culling, stippling, unfilled tris, etc.

src/gallium/auxiliary/draw/draw_gs.c

@@ -791,6 +791,12 @@ draw_create_geometry_shader(struct draw_context *draw,
          gs->position_output = i;
       if (gs->info.output_semantic_name[i] == TGSI_SEMANTIC_VIEWPORT_INDEX)
          gs->viewport_index_output = i;
+      if (gs->info.output_semantic_name[i] == TGSI_SEMANTIC_CLIPDIST) {
+         if (gs->info.output_semantic_index[i] == 0)
+            gs->clipdistance_output[0] = i;
+         else
+            gs->clipdistance_output[1] = i;
+      }
    }
 
    gs->machine = draw->gs.tgsi.machine;

src/gallium/auxiliary/draw/draw_gs.h

@@ -67,6 +67,7 @@ struct draw_geometry_shader {
    struct tgsi_shader_info info;
    unsigned position_output;
    unsigned viewport_index_output;
+   unsigned clipdistance_output[2];
 
    unsigned max_output_vertices;
    unsigned primitive_boundary;

src/gallium/auxiliary/draw/draw_private.h

@@ -389,6 +389,7 @@ uint draw_current_shader_position_output(const struct draw_context *draw);
 uint draw_current_shader_viewport_index_output(const struct draw_context *draw);
 uint draw_current_shader_clipvertex_output(const struct draw_context *draw);
 uint draw_current_shader_clipdistance_output(const struct draw_context *draw, int index);
+uint draw_current_shader_num_written_clipdistances(const struct draw_context *draw);
 int draw_alloc_extra_vertex_attrib(struct draw_context *draw,
                                    uint semantic_name, uint semantic_index);
 void draw_remove_extra_vertex_attribs(struct draw_context *draw);

src/gallium/auxiliary/tgsi/tgsi_scan.c

@@ -196,7 +196,7 @@ tgsi_scan_shader(const struct tgsi_token *tokens,
                   info->output_semantic_index[reg] = (ubyte)fulldecl->Semantic.Index;
                   info->num_outputs++;
 
-                  if (procType == TGSI_PROCESSOR_VERTEX &&
+                  if ((procType == TGSI_PROCESSOR_VERTEX || procType == TGSI_PROCESSOR_GEOMETRY) &&
                       fulldecl->Semantic.Name == TGSI_SEMANTIC_CLIPDIST) {
                      info->num_written_clipdistance += util_bitcount(fulldecl->Declaration.UsageMask);
                   }