st/mesa: use Elements() instead of hard-coded number

And add a comment about the velems_util_draw[] array.

diff --git a/src/mesa/state_tracker/st_context.c b/src/mesa/state_tracker/st_context.c
index 7735eee..2e14da2 100644 (file)
--- a/src/mesa/state_tracker/st_context.c
+++ b/src/mesa/state_tracker/st_context.c
@@ -163,7 +163,10 @@ st_create_context_priv( struct gl_context *ctx, struct pipe_context *pipe )
    else
       st->internal_target = PIPE_TEXTURE_RECT;
 
-   for (i = 0; i < 3; i++) {
+   /* Vertex element objects used for drawing rectangles for glBitmap,
+    * glDrawPixels, glClear, etc.
+    */
+   for (i = 0; i < Elements(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;