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, 2 deletions

diff --git a/src/gallium/drivers/softpipe/sp_surface.c b/src/gallium/drivers/softpipe/sp_surface.c
index bb143f4cb3a..911c34df1b8 100644
--- a/src/gallium/drivers/softpipe/sp_surface.c
+++ b/src/gallium/drivers/softpipe/sp_surface.c
@@ -56,8 +56,7 @@ static void sp_blit(struct pipe_context *pipe,
 
    /* XXX turn off occlusion and streamout queries */
 
-   util_blitter_save_vertex_buffers(sp->blitter, sp->num_vertex_buffers,
-                                    sp->vertex_buffer);
+   util_blitter_save_vertex_buffer_slot(sp->blitter, sp->vertex_buffer);
    util_blitter_save_vertex_elements(sp->blitter, sp->velems);
    util_blitter_save_vertex_shader(sp->blitter, sp->vs);
    util_blitter_save_geometry_shader(sp->blitter, sp->gs);