[Mesa-dev] [PATCH 3/3] draw/so: maintain an exact number of written vertices

[Zack Rusin]

It's quite helpful during the rendering when we know
exactly the count of the vertices available in the
buffer.

Signed-off-by: Zack Rusin <zackr at vmware.com>
---
 src/gallium/auxiliary/draw/draw_context.h    |    1 +
 src/gallium/auxiliary/draw/draw_pt.c         |   18 +++++++++++-------
 src/gallium/auxiliary/draw/draw_pt_so_emit.c |    4 +++-
 3 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/src/gallium/auxiliary/draw/draw_context.h b/src/gallium/auxiliary/draw/draw_context.h
index 369f6c8..b333457 100644
--- a/src/gallium/auxiliary/draw/draw_context.h
+++ b/src/gallium/auxiliary/draw/draw_context.h
@@ -60,6 +60,7 @@ struct draw_so_target {
    struct pipe_stream_output_target target;
    void *mapping;
    int internal_offset;
+   int emitted_vertices;
 };
 
 struct draw_context *draw_create( struct pipe_context *pipe );
diff --git a/src/gallium/auxiliary/draw/draw_pt.c b/src/gallium/auxiliary/draw/draw_pt.c
index 50b9efa..7026dbf 100644
--- a/src/gallium/auxiliary/draw/draw_pt.c
+++ b/src/gallium/auxiliary/draw/draw_pt.c
@@ -468,10 +468,20 @@ draw_vbo(struct draw_context *draw,
    assert(info->instance_count > 0);
    if (info->indexed)
       assert(draw->pt.user.elts);
+   
+   count = info->count;
+   if (count == 0) {
+      if (info->count_from_stream_output)
+         count = draw->pt.max_index + 1;
+   }
 
    draw->pt.user.eltBias = info->index_bias;
    draw->pt.user.min_index = info->min_index;
-   draw->pt.user.max_index = info->max_index;
+   if (info->count_from_stream_output) {
+      draw->pt.user.max_index = count;
+   } else {
+      draw->pt.user.max_index = info->max_index;
+   }
    draw->pt.user.eltSize = info->indexed ? draw->pt.user.eltSizeIB : 0;
 
    if (0)
@@ -518,12 +528,6 @@ draw_vbo(struct draw_context *draw,
 
    draw->pt.max_index = index_limit - 1;
 
-   count = info->count;
-   if (count == 0) {
-      if (info->count_from_stream_output)
-         count = draw->pt.max_index + 1;
-   }
-
    /*
     * TODO: We could use draw->pt.max_index to further narrow
     * the min_index/max_index hints given by the state tracker.
diff --git a/src/gallium/auxiliary/draw/draw_pt_so_emit.c b/src/gallium/auxiliary/draw/draw_pt_so_emit.c
index 25584a9..ae071a6 100644
--- a/src/gallium/auxiliary/draw/draw_pt_so_emit.c
+++ b/src/gallium/auxiliary/draw/draw_pt_so_emit.c
@@ -174,8 +174,10 @@ static void so_emit_prim(struct pt_so_emit *so,
          else
             memcpy(buffer, &input[idx][start_comp], num_comps * sizeof(float));
       }
-      for (ob = 0; ob < draw->so.num_targets; ++ob)
+      for (ob = 0; ob < draw->so.num_targets; ++ob) {
          draw->so.targets[ob]->internal_offset += state->stride[ob] * sizeof(float);
+         draw->so.targets[ob]->emitted_vertices += 1;
+      }
    }
    so->emitted_vertices += num_vertices;
    ++so->emitted_primitives;
-- 
1.7.10.4