gallium/util: implement layered framebuffer clear in u_blitter

All bound layers (from first_layer to last_layer) should be cleared.

This uses a vertex shader which outputs gl_Layer = gl_InstanceID, so each
instance goes to a different layer. By rendering a quad and setting
the instance count to the number of layers, it will trivially clear all
layers.

This requires AMD_vertex_shader_layer (or PIPE_CAP_TGSI_VS_LAYER), which only
radeonsi supports at the moment. r600 could do this too. Standard DX11
hardware will have to use a geometry shader though, which has higher overhead.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/gallium/auxiliary/util/u_blitter.h b/src/gallium/auxiliary/util/u_blitter.h
index d9cefde500a..24c11115573 100644
--- a/src/gallium/auxiliary/util/u_blitter.h
+++ b/src/gallium/auxiliary/util/u_blitter.h
@@ -183,7 +183,7 @@ void util_blitter_draw_rectangle(struct blitter_context *blitter,
  * - blend state
  */
 void util_blitter_clear(struct blitter_context *blitter,
-                        unsigned width, unsigned height,
+                        unsigned width, unsigned height, unsigned num_layers,
                         unsigned clear_buffers,
                         const union pipe_color_union *color,
                         double depth, unsigned stencil);