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, 7 insertions, 4 deletions

diff --git a/src/gallium/auxiliary/util/u_draw_quad.c b/src/gallium/auxiliary/util/u_draw_quad.c
index 81c4f107ea9..3fe324afa80 100644
--- a/src/gallium/auxiliary/util/u_draw_quad.c
+++ b/src/gallium/auxiliary/util/u_draw_quad.c
@@ -42,6 +42,7 @@ void
 util_draw_vertex_buffer(struct pipe_context *pipe,
                         struct cso_context *cso,
                         struct pipe_resource *vbuf,
+                        uint vbuf_slot,
                         uint offset,
                         uint prim_type,
                         uint num_verts,
@@ -60,10 +61,10 @@ util_draw_vertex_buffer(struct pipe_context *pipe,
    /* note: vertex elements already set by caller */
 
    if (cso) {
-      cso_set_vertex_buffers(cso, 1, &vbuffer);
+      cso_set_vertex_buffers(cso, vbuf_slot, 1, &vbuffer);
       cso_draw_arrays(cso, prim_type, 0, num_verts);
    } else {
-      pipe->set_vertex_buffers(pipe, 1, &vbuffer);
+      pipe->set_vertex_buffers(pipe, vbuf_slot, 1, &vbuffer);
       util_draw_arrays(pipe, prim_type, 0, num_verts);
    }
 }
@@ -86,7 +87,7 @@ util_draw_user_vertex_buffer(struct cso_context *cso, void *buffer,
 
    /* note: vertex elements already set by caller */
 
-   cso_set_vertex_buffers(cso, 1, &vbuffer);
+   cso_set_vertex_buffers(cso, 0, 1, &vbuffer);
    cso_draw_arrays(cso, prim_type, 0, num_verts);
 }
 
@@ -97,6 +98,7 @@ util_draw_user_vertex_buffer(struct cso_context *cso, void *buffer,
  */
 void 
 util_draw_texquad(struct pipe_context *pipe, struct cso_context *cso,
+                  uint vbuf_slot,
                   float x0, float y0, float x1, float y1, float z)
 {
    uint numAttribs = 2, i, j;
@@ -145,7 +147,8 @@ util_draw_texquad(struct pipe_context *pipe, struct cso_context *cso,
       goto out;
    pipe_buffer_write(pipe, vbuf, 0, vertexBytes, v);
 
-   util_draw_vertex_buffer(pipe, cso, vbuf, 0, PIPE_PRIM_TRIANGLE_FAN, 4, 2);
+   util_draw_vertex_buffer(pipe, cso, vbuf, vbuf_slot, 0,
+                           PIPE_PRIM_TRIANGLE_FAN, 4, 2);
 
 out:
    if (vbuf)