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, 1 insertions, 3 deletions

diff --git a/src/gallium/drivers/nv30/nv30_miptree.c b/src/gallium/drivers/nv30/nv30_miptree.c
index e89725feb2f..5d941ab771e 100644
--- a/src/gallium/drivers/nv30/nv30_miptree.c
+++ b/src/gallium/drivers/nv30/nv30_miptree.c
@@ -193,9 +193,7 @@ nv30_blit(struct pipe_context *pipe,
 
    /* XXX turn off occlusion queries */
 
-   util_blitter_save_vertex_buffers(nv30->blitter,
-                                    nv30->num_vtxbufs,
-                                    nv30->vtxbuf);
+   util_blitter_save_vertex_buffer_slot(nv30->blitter, nv30->vtxbuf);
    util_blitter_save_vertex_elements(nv30->blitter, nv30->vertex);
    util_blitter_save_vertex_shader(nv30->blitter, nv30->vertprog.program);
    util_blitter_save_rasterizer(nv30->blitter, nv30->rast);