draw: add code to reset instance dependent data

We want to be able to reset certain parts of the pipeline,
in particular the input primitive index, but only either with
seperate invocations of the draw_vbo or new instances. In all
other cases (e.g. new invocations due to primitive restart)
that data needs to be preserved. Add a function through which
we can reset instance dependent data.

Signed-off-by: Zack Rusin <[email protected]>
Reviewed-by: José Fonseca <[email protected]>

5 files changed, 31 insertions, 1 deletions

diff --git a/src/gallium/auxiliary/draw/draw_context.c b/src/gallium/auxiliary/draw/draw_context.c
index 5272951d2b3..25f79ae19e6 100644
--- a/src/gallium/auxiliary/draw/draw_context.c
+++ b/src/gallium/auxiliary/draw/draw_context.c
@@ -156,6 +156,19 @@ boolean draw_init(struct draw_context *draw)
    return TRUE;
 }
 
+/*
+ * Called whenever we're starting to draw a new instance.
+ * Some internal structures don't want to have to reset internal
+ * members on each invocation (because their state might have to persist
+ * between multiple primitive restart rendering call) but might have to 
+ * for each new instance. 
+ * This is particularly the case for primitive id's in geometry shader.
+ */
+void draw_new_instance(struct draw_context *draw)
+{
+   draw_geometry_shader_new_instance(draw->gs.geometry_shader);
+}
+
 
 void draw_destroy( struct draw_context *draw )
 {
diff --git a/src/gallium/auxiliary/draw/draw_gs.c b/src/gallium/auxiliary/draw/draw_gs.c
index 2f94eaeda4f..fbb01b457d1 100644
--- a/src/gallium/auxiliary/draw/draw_gs.c
+++ b/src/gallium/auxiliary/draw/draw_gs.c
@@ -560,7 +560,6 @@ int draw_geometry_shader_run(struct draw_geometry_shader *shader,
    shader->emitted_primitives = 0;
    shader->vertex_size = vertex_size;
    shader->tmp_output = (float (*)[4])output_verts->verts->data;
-   shader->in_prim_idx = 0;
    shader->fetched_prim_count = 0;
    shader->input_vertex_stride = input_stride;
    shader->input = input;
@@ -869,3 +868,16 @@ void draw_gs_set_current_variant(struct draw_geometry_shader *shader,
    shader->current_variant = variant;
 }
 #endif
+
+/*
+ * Called at the very begin of the draw call with a new instance
+ * Used to reset state that should persist between primitive restart.
+ */
+void
+draw_geometry_shader_new_instance(struct draw_geometry_shader *gs)
+{
+   if (!gs)
+      return;
+
+   gs->in_prim_idx = 0;
+}
diff --git a/src/gallium/auxiliary/draw/draw_gs.h b/src/gallium/auxiliary/draw/draw_gs.h
index ca744cebfc9..46d2d614f06 100644
--- a/src/gallium/auxiliary/draw/draw_gs.h
+++ b/src/gallium/auxiliary/draw/draw_gs.h
@@ -114,6 +114,8 @@ struct draw_geometry_shader {
                    unsigned input_primitives);
 };
 
+void draw_geometry_shader_new_instance(struct draw_geometry_shader *gs);
+
 /*
  * Returns the number of vertices emitted.
  * The vertex shader can emit any number of vertices as long as it's
diff --git a/src/gallium/auxiliary/draw/draw_private.h b/src/gallium/auxiliary/draw/draw_private.h
index d6a3e7c2cee..25a8ae61498 100644
--- a/src/gallium/auxiliary/draw/draw_private.h
+++ b/src/gallium/auxiliary/draw/draw_private.h
@@ -355,6 +355,7 @@ struct draw_prim_info {
  * Draw common initialization code
  */
 boolean draw_init(struct draw_context *draw);
+void draw_new_instance(struct draw_context *draw);
 
 /*******************************************************************************
  * Vertex shader code:
diff --git a/src/gallium/auxiliary/draw/draw_pt.c b/src/gallium/auxiliary/draw/draw_pt.c
index 10f32fd929f..602d076dce2 100644
--- a/src/gallium/auxiliary/draw/draw_pt.c
+++ b/src/gallium/auxiliary/draw/draw_pt.c
@@ -561,6 +561,8 @@ draw_vbo(struct draw_context *draw,
    for (instance = 0; instance < info->instance_count; instance++) {
       draw->instance_id = instance + info->start_instance;
 
+      draw_new_instance(draw);
+
       if (info->primitive_restart) {
          draw_pt_arrays_restart(draw, info);
       }