gallium: beginnings of draw module vertex rework

Trying to put a structure in place that we can actually optimize.
Initially just implementing a passthrough mode, this will fairly soon
replace all the vertex_cache/prim_queue/shader_queue stuff that's so
hard to understand...

Split the vertex processing into a couple of distinct stages:
- Frontend
    - Prepares two lists of elements (fetch and draw) to be processed
      by the next stage.  This stage doesn't fetch or draw vertices, but
      makes the decision which to draw.  Multiple implementations of this
      will implement different strategies, currently just a vcache
      implementation.
- MiddleEnd
    - Takes the list of fetch elements, fetches them, runs the vertex
      shader, cliptest, viewport transform on them to produce a
      linear array of vertex_header vertices.
    - Passes that list of vertices, plus the draw_elements (which index
      into that list) onto the backend
- Backend
    - Either the existing primitive/clipping pipeline, or the vbuf_render
      hardware backend provided by the driver.

Currently, the middle-end is the old passthrough code, and it build hardware
vertices, not vertex_header vertices as above.  It may be that passthrough
is a special case in this respect.

1 files changed, 30 insertions, 3 deletions

diff --git a/src/gallium/auxiliary/draw/draw_private.h b/src/gallium/auxiliary/draw/draw_private.h
index 1c65c3d1b2..0c5afcacfa 100644
--- a/src/gallium/auxiliary/draw/draw_private.h
+++ b/src/gallium/auxiliary/draw/draw_private.h
@@ -53,6 +53,9 @@ struct pipe_context;
 struct gallivm_prog;
 struct gallivm_cpu_engine;
 
+struct draw_pt_middle_end;
+struct draw_pt_front_end;
+
 /**
  * Basic vertex info.
  * Carry some useful information around with the vertices in the prim pipe.  
@@ -203,8 +206,21 @@ struct draw_context
    /* Support prototype passthrough path:
     */
    struct {
-      unsigned prim;
-      unsigned hw_vertex_size;
+      unsigned prim;           /* XXX: to be removed */
+      unsigned hw_vertex_size; /* XXX: to be removed */
+
+      struct {
+         struct draw_pt_middle_end *fetch_emit;
+         struct draw_pt_middle_end *fetch_shade_emit;
+         struct draw_pt_middle_end *fetch_shade_cliptest_pipeline_or_emit;
+      } middle;
+
+      struct {
+         struct draw_pt_front_end *noop;
+         struct draw_pt_front_end *split_arrays;
+         struct draw_pt_front_end *vcache;
+      } front;
+
    } pt;
 
 
@@ -351,7 +367,18 @@ extern void draw_update_vertex_fetch( struct draw_context *draw );
 extern boolean draw_need_pipeline(const struct draw_context *draw);
 
 
-/* Prototype/hack
+/* Passthrough mode (second attempt):
+ */
+boolean draw_pt_init( struct draw_context *draw );
+void draw_pt_destroy( struct draw_context *draw );
+boolean draw_pt_arrays( struct draw_context *draw,
+                        unsigned prim,
+                        unsigned start,
+                        unsigned count );
+
+
+
+/* Prototype/hack (DEPRECATED)
  */
 boolean
 draw_passthrough_arrays(struct draw_context *draw,