vbo: introduce vbo_get_minmax_indices function

Introduce vbo_get_minmax_indices() function to handle the min/max index
computation for nr_prims(>= 1). The old code just compute the first
prim's min/max index; this would results an error rendering if user
called functions like glMultiDrawElements(). This patch servers as
fixing this issue.

As when nr_prims = 1, we can pass 1 to paramter nr_prims, thus I made
vbo_get_minmax_index() static.

v2: per Roland's suggestion, put the indices address compuation into
    vbo_get_minmax_index() instead.

    Also do comination if possible to reduce map/unmap count

v3: per Brian's suggestion, use a pointer for start_prim to avoid
    structure copy per loop.

Signed-off-by: Yuanhan Liu <[email protected]>
Reviewed-by: Roland Scheidegger <[email protected]>
Reviewed-by: Brian Paul <[email protected]>

2 files changed, 3 insertions, 2 deletions

diff --git a/src/mesa/state_tracker/st_draw.c b/src/mesa/state_tracker/st_draw.c
index 6d6fc858de4..c0554cfc70a 100644
--- a/src/mesa/state_tracker/st_draw.c
+++ b/src/mesa/state_tracker/st_draw.c
@@ -990,7 +990,8 @@ st_draw_vbo(struct gl_context *ctx,
       /* Gallium probably doesn't want this in some cases. */
       if (!index_bounds_valid)
          if (!all_varyings_in_vbos(arrays))
-            vbo_get_minmax_index(ctx, prims, ib, &min_index, &max_index);
+            vbo_get_minmax_indices(ctx, prims, ib, &min_index, &max_index,
+                                   nr_prims);
 
       for (i = 0; i < nr_prims; i++) {
          num_instances = MAX2(num_instances, prims[i].num_instances);
diff --git a/src/mesa/state_tracker/st_draw_feedback.c b/src/mesa/state_tracker/st_draw_feedback.c
index fbf0349b41b..a559b733ac2 100644
--- a/src/mesa/state_tracker/st_draw_feedback.c
+++ b/src/mesa/state_tracker/st_draw_feedback.c
@@ -119,7 +119,7 @@ st_feedback_draw_vbo(struct gl_context *ctx,
    st_validate_state(st);
 
    if (!index_bounds_valid)
-      vbo_get_minmax_index(ctx, prims, ib, &min_index, &max_index);
+      vbo_get_minmax_indices(ctx, prims, ib, &min_index, &max_index, nr_prims);
 
    /* must get these after state validation! */
    vp = st->vp;