softpipe: fix mapping of "special" vs outputs

Unlike llvmpipe, softpipe always tells draw to emit the vertices as-is.
The two vertex layouts it calculates are a bit confusing, one which is just
used to tell draw to emit vertices as-is, and the other which has draw written
all over it but draw is completely unaware of and is used only to look up the
correct interpolation info later in setup.
Thus, the slots used are different to what llvmpipe does (I'm going to clean
up the confusing two layout stuff).

Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>

1 files changed, 17 insertions, 12 deletions

diff --git a/src/gallium/drivers/softpipe/sp_state_derived.c b/src/gallium/drivers/softpipe/sp_state_derived.c
index 7e998af..56ecc3b 100644
--- a/src/gallium/drivers/softpipe/sp_state_derived.c
+++ b/src/gallium/drivers/softpipe/sp_state_derived.c
@@ -79,10 +79,14 @@ softpipe_get_vertex_info(struct softpipe_context *softpipe)
        */
       vinfo_vbuf->num_attribs = 0;
       for (i = 0; i < num; i++) {
-	 draw_emit_vertex_attr(vinfo_vbuf, EMIT_4F, INTERP_PERSPECTIVE, i);
+         draw_emit_vertex_attr(vinfo_vbuf, EMIT_4F, INTERP_PERSPECTIVE, i);
       }
       draw_compute_vertex_size(vinfo_vbuf);
 
+      softpipe->viewport_index_slot = 0;
+      softpipe->layer_slot = 0;
+      softpipe->psize_slot = 0;
+
       /*
        * Loop over fragment shader inputs, searching for the matching output
        * from the vertex shader.
@@ -128,10 +132,15 @@ softpipe_get_vertex_info(struct softpipe_context *softpipe)
          src = draw_find_shader_output(softpipe->draw,
                                        fsInfo->input_semantic_name[i],
                                        fsInfo->input_semantic_index[i]);
-	 if (fsInfo->input_semantic_name[i] == TGSI_SEMANTIC_COLOR && src == -1)
-	   /* try and find a bcolor */
-	   src = draw_find_shader_output(softpipe->draw,
-					 TGSI_SEMANTIC_BCOLOR, fsInfo->input_semantic_index[i]);
+         if (fsInfo->input_semantic_name[i] == TGSI_SEMANTIC_COLOR && src == -1)
+            /*
+             * try and find a bcolor.
+             * Note that if there's both front and back color, draw will
+             * have copied back to front color already.
+             */
+            src = draw_find_shader_output(softpipe->draw,
+                                          TGSI_SEMANTIC_BCOLOR,
+                                          fsInfo->input_semantic_index[i]);
 
          draw_emit_vertex_attr(vinfo, EMIT_4F, interp, src);
       }
@@ -141,7 +150,7 @@ softpipe_get_vertex_info(struct softpipe_context *softpipe)
                                          TGSI_SEMANTIC_PSIZE, 0);
 
       if (vs_index >= 0) {
-         softpipe->psize_slot = vinfo->num_attribs;
+         softpipe->psize_slot = vs_index;
          draw_emit_vertex_attr(vinfo, EMIT_4F, INTERP_CONSTANT, vs_index);
       }
 
@@ -150,10 +159,8 @@ softpipe_get_vertex_info(struct softpipe_context *softpipe)
                                          TGSI_SEMANTIC_VIEWPORT_INDEX,
                                          0);
       if (vs_index >= 0) {
-         softpipe->viewport_index_slot = vinfo->num_attribs;
+         softpipe->viewport_index_slot = vs_index;
          draw_emit_vertex_attr(vinfo, EMIT_4F, INTERP_CONSTANT, vs_index);
-      } else {
-         softpipe->viewport_index_slot = 0;
       }
 
       /* Figure out if we need layer */
@@ -161,10 +168,8 @@ softpipe_get_vertex_info(struct softpipe_context *softpipe)
                                          TGSI_SEMANTIC_LAYER,
                                          0);
       if (vs_index >= 0) {
-         softpipe->layer_slot = vinfo->num_attribs;
+         softpipe->layer_slot = vs_index;
          draw_emit_vertex_attr(vinfo, EMIT_4F, INTERP_CONSTANT, vs_index);
-      } else {
-         softpipe->layer_slot = 0;
       }
 
       draw_compute_vertex_size(vinfo);