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, 3 insertions, 2 deletions

diff --git a/src/gallium/drivers/noop/noop_state.c b/src/gallium/drivers/noop/noop_state.c
index dbfe35b668c..16ce9b457d9 100644
--- a/src/gallium/drivers/noop/noop_state.c
+++ b/src/gallium/drivers/noop/noop_state.c
@@ -215,8 +215,9 @@ static void noop_set_index_buffer(struct pipe_context *ctx,
 {
 }
 
-static void noop_set_vertex_buffers(struct pipe_context *ctx, unsigned count,
-					const struct pipe_vertex_buffer *buffers)
+static void noop_set_vertex_buffers(struct pipe_context *ctx,
+				    unsigned start_slot, unsigned count,
+				    const struct pipe_vertex_buffer *buffers)
 {
 }