st/mesa: implement PBO upload for multiple layers

Use instancing to generate two triangles for each destination layer and use
a geometry shader to route the layer index.

v2:
- directly write layer in VS if supported by the driver (Marek Olšák)

Reviewed-by: Edward O'Callaghan <[email protected]>

1 files changed, 3 insertions, 0 deletions

diff --git a/src/mesa/state_tracker/st_context.h b/src/mesa/state_tracker/st_context.h
index fa0fa104a9a..57076ad0d18 100644
--- a/src/mesa/state_tracker/st_context.h
+++ b/src/mesa/state_tracker/st_context.h
@@ -209,9 +209,12 @@ struct st_context
       struct pipe_rasterizer_state raster;
       struct pipe_blend_state blend;
       void *vs;
+      void *gs;
       void *fs;
       bool enabled;
       bool rgba_only;
+      bool upload_layers;
+      bool use_gs;
    } pbo_upload;
 
    /** used for anything using util_draw_vertex_buffer */