gallium: add start_slot parameter to set_vertex_buffers

This allows updating only a subrange of buffer bindings.

set_vertex_buffers(pipe, start_slot, count, NULL) unbinds buffers in that
range. Binding NULL resources unbinds buffers too (both buffer and user_buffer
must be NULL).

The meta ops are adapted to only save, change, and restore the single slot
they use. The cso_context can save and restore only one vertex buffer slot.
The clients can query which one it is using cso_get_aux_vertex_buffer_slot.
It's currently set to 0. (the Draw module breaks if it's set to non-zero)

It should decrease the CPU overhead when using a lot of meta ops, but
the drivers must be able to treat each vertex buffer slot as a separate
state (only r600g does so at the moment).

I can imagine this also being useful for optimizing some OpenGL use cases.

Reviewed-by: Brian Paul <[email protected]>

1 files changed, 6 insertions, 2 deletions

diff --git a/src/gallium/drivers/nv30/nv30_draw.c b/src/gallium/drivers/nv30/nv30_draw.c
index 46e85362815..51fe4f86ed1 100644
--- a/src/gallium/drivers/nv30/nv30_draw.c
+++ b/src/gallium/drivers/nv30/nv30_draw.c
@@ -379,7 +379,7 @@ nv30_render_vbo(struct pipe_context *pipe, const struct pipe_draw_info *info)
    if (nv30->draw_dirty & NV30_NEW_CLIP)
       draw_set_clip_state(draw, &nv30->clip);
    if (nv30->draw_dirty & NV30_NEW_ARRAYS) {
-      draw_set_vertex_buffers(draw, nv30->num_vtxbufs, nv30->vtxbuf);
+      draw_set_vertex_buffers(draw, 0, nv30->num_vtxbufs, nv30->vtxbuf);
       draw_set_vertex_elements(draw, nv30->vertex->num_elements, nv30->vertex->pipe);
    }
    if (nv30->draw_dirty & NV30_NEW_FRAGPROG) {
@@ -404,10 +404,14 @@ nv30_render_vbo(struct pipe_context *pipe, const struct pipe_draw_info *info)
 
    for (i = 0; i < nv30->num_vtxbufs; i++) {
       const void *map = nv30->vtxbuf[i].user_buffer;
-      if (!map)
+      if (!map) {
+         if (!nv30->vtxbuf[i].buffer) {
+            continue;
+         }
          map = pipe_buffer_map(pipe, nv30->vtxbuf[i].buffer,
                                   PIPE_TRANSFER_UNSYNCHRONIZED |
                                   PIPE_TRANSFER_READ, &transfer[i]);
+      }
       draw_set_mapped_vertex_buffer(draw, i, map);
    }