st/mesa: overhaul vertex setup for clearing, glDrawPixels, glBitmap

Define a new st_util_vertex structure which is a bit smaller (9 floats
versus the previous 12 floats per vertex).  Clean up the glClear,
glDrawPixels and glBitmap code that sets up the vertex data and does the
drawing so it's all very similar.  This can lead to more consolidation.

v2: add assertion that vertex buffer slot == 0 to catch possible future
change in cso_get_aux_vertex_buffer_slot() behavior.

Reviewed-by: Jose Fonseca <jfonseca@vmware.com>

1 files changed, 23 insertions, 9 deletions

diff --git a/src/mesa/state_tracker/st_context.c b/src/mesa/state_tracker/st_context.c
index cba7f74..65a5218 100644
--- a/src/mesa/state_tracker/st_context.c
+++ b/src/mesa/state_tracker/st_context.c
@@ -248,16 +248,30 @@ st_create_context_priv( struct gl_context *ctx, struct pipe_context *pipe,
    else
       st->internal_target = PIPE_TEXTURE_RECT;
 
-   /* Vertex element objects used for drawing rectangles for glBitmap,
-    * glDrawPixels, glClear, etc.
+   /* Setup vertex element info for 'struct st_util_vertex'.
     */
-   for (i = 0; i < ARRAY_SIZE(st->velems_util_draw); i++) {
-      memset(&st->velems_util_draw[i], 0, sizeof(struct pipe_vertex_element));
-      st->velems_util_draw[i].src_offset = i * 4 * sizeof(float);
-      st->velems_util_draw[i].instance_divisor = 0;
-      st->velems_util_draw[i].vertex_buffer_index =
-            cso_get_aux_vertex_buffer_slot(st->cso_context);
-      st->velems_util_draw[i].src_format = PIPE_FORMAT_R32G32B32A32_FLOAT;
+   {
+      const unsigned slot = cso_get_aux_vertex_buffer_slot(st->cso_context);
+
+      /* If this assertion ever fails all state tracker calls to
+       * cso_get_aux_vertex_buffer_slot() should be audited.  This
+       * particular call would have to be moved to just before each
+       * drawing call.
+       */
+      assert(slot == 0);
+
+      STATIC_ASSERT(sizeof(struct st_util_vertex) == 9 * sizeof(float));
+
+      memset(&st->util_velems, 0, sizeof(st->util_velems));
+      st->util_velems[0].src_offset = 0;
+      st->util_velems[0].vertex_buffer_index = slot;
+      st->util_velems[0].src_format = PIPE_FORMAT_R32G32B32_FLOAT;
+      st->util_velems[1].src_offset = 3 * sizeof(float);
+      st->util_velems[1].vertex_buffer_index = slot;
+      st->util_velems[1].src_format = PIPE_FORMAT_R32G32B32A32_FLOAT;
+      st->util_velems[2].src_offset = 7 * sizeof(float);
+      st->util_velems[2].vertex_buffer_index = slot;
+      st->util_velems[2].src_format = PIPE_FORMAT_R32G32_FLOAT;
    }
 
    /* we want all vertex data to be placed in buffer objects */