Initial work for post-transform vertex feedback buffers.

This will be used for:
  GL_NV_transform_feedback, or GL3 equivalent.
  RasterPos
  GL select/feedback modes

src/mesa/pipe/draw/draw_feedback.c

@@ -0,0 +1,247 @@
+/**************************************************************************
+ * 
+ * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ * 
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+ * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ * 
+ **************************************************************************/
+
+/**
+ * Primitive/vertex feedback (and/or discard) stage.
+ * Used to implement transformation feedback/streaming and other things
+ * which require a post-transformed vertex position (such as rasterpos,
+ * selection and feedback modes).
+ *
+ * Authors:
+ *  Brian Paul
+ */
+
+
+#include "pipe/p_util.h"
+#include "draw_private.h"
+
+
+struct feedback_stage {
+   struct draw_stage stage;      /**< base class */
+   uint num_prim_generated;      /**< number of primitives received */
+   uint num_prim_emitted;        /**< number of primitives fed back */
+   uint num_vert_emitted;        /**< number of vertices fed back */
+   uint max_vert_emit;           /**< max number of verts we can emit */
+   float *dest[PIPE_MAX_FEEDBACK_ATTRIBS];  /**< dests for vertex attribs */
+};
+
+
+
+/**
+ * Check if there's space to store 'numVerts' in the feedback buffer(s).
+ */
+static boolean
+check_space(const struct draw_stage *stage, uint numVerts)
+{
+   const struct feedback_stage *fs = (struct feedback_stage *) stage;
+   return fs->num_vert_emitted + numVerts <= fs->max_vert_emit;
+}
+
+
+/**
+ * Record the given vertex's attributes into the feedback buffer(s).
+ */
+static void
+feedback_vertex(struct draw_stage *stage, const struct vertex_header *vertex)
+{
+   struct feedback_stage *fs = (struct feedback_stage *) stage;
+   const struct pipe_feedback_state *feedback = &stage->draw->feedback;
+   const uint select = feedback->interleaved ? 0 : 1;
+   uint i;
+
+   /*
+    * Note: 'select' is either 0 or 1.  By multiplying 'i' by 'select'
+    * we can either address output buffer 0 (for interleaving) or
+    * output buffer i (for non-interleaved).
+    */
+
+   for (i = 0; i < feedback->num_attribs; i++) {
+      const uint attr = feedback->attrib[i];
+      const float *src = attr ? vertex->data[attr] : vertex->clip;
+      const uint size = feedback->size[i];
+      float *dest = fs->dest[i * select];
+
+      switch (size) {
+      case 4:
+         dest[3] = src[3];
+         /* fall-through */
+      case 3:
+         dest[2] = src[2];
+         /* fall-through */
+      case 2:
+         dest[1] = src[1];
+         /* fall-through */
+      case 1:
+         dest[0] = src[0];
+         /* fall-through */
+      default:
+         ;
+      }
+      fs->dest[i * select] += size;
+   }
+
+   fs->num_vert_emitted++;
+}
+
+
+static void feedback_begin( struct draw_stage *stage )
+{
+   struct feedback_stage *fs = (struct feedback_stage *) stage;
+   const struct pipe_feedback_state *feedback = &stage->draw->feedback;
+
+   fs->num_prim_generated = 0;
+   fs->num_prim_emitted = 0;
+   fs->num_vert_emitted = 0;
+
+   assert(feedback->enabled);
+
+   /* Compute max_vert_emit, the max number of vertices we can emit.
+    * And, setup dest[] pointers.
+    */
+   if (stage->draw->feedback.interleaved) {
+      uint i, vertex_size = 0;
+      /* compute size of each interleaved vertex, in floats */
+      for (i = 0; i < feedback->num_attribs; i++) {
+         vertex_size += feedback->size[i];
+      }
+      /* compute max number of vertices we can feedback */
+      fs->max_vert_emit = stage->draw->mapped_feedback_buffer_size[0]
+         / sizeof(float) / vertex_size;
+
+      fs->dest[0] = (float *) stage->draw->mapped_feedback_buffer[0];
+   }
+   else {
+      uint i;
+      uint max = ~0;
+      for (i = 0; i < feedback->num_attribs; i++) {
+         uint n = stage->draw->mapped_feedback_buffer_size[i]
+            / sizeof(float) / feedback->size[i];
+         if (n < max)
+            max = n;
+         fs->dest[i] = (float *) stage->draw->mapped_feedback_buffer[i];
+      }
+      fs->max_vert_emit = max;
+   }
+
+   if (!feedback->discard)
+      stage->next->begin( stage->next );
+}
+
+
+static void feedback_tri( struct draw_stage *stage,
+                          struct prim_header *header )
+{
+   struct feedback_stage *fs = (struct feedback_stage *) stage;
+
+   fs->num_prim_generated++;
+
+   if (stage->draw->feedback.enabled && check_space(stage, 3)) {
+      feedback_vertex(stage, header->v[0]);
+      feedback_vertex(stage, header->v[1]);
+      feedback_vertex(stage, header->v[2]);
+      fs->num_prim_emitted++;
+   }
+
+   if (!stage->draw->feedback.discard)
+      stage->next->tri( stage->next, header );
+}
+
+
+static void feedback_line( struct draw_stage *stage,
+                           struct prim_header *header )
+{
+   struct feedback_stage *fs = (struct feedback_stage *) stage;
+
+   fs->num_prim_generated++;
+
+   if (stage->draw->feedback.enabled && check_space(stage, 2)) {
+      feedback_vertex(stage, header->v[0]);
+      feedback_vertex(stage, header->v[1]);
+      fs->num_prim_emitted++;
+   }
+
+   if (!stage->draw->feedback.discard)
+      stage->next->line( stage->next, header );
+}
+
+
+static void feedback_point( struct draw_stage *stage,
+                            struct prim_header *header )
+{
+   struct feedback_stage *fs = (struct feedback_stage *) stage;
+
+   fs->num_prim_generated++;
+
+   if (stage->draw->feedback.enabled && check_space(stage, 1)) {
+      feedback_vertex(stage, header->v[0]);
+      fs->num_prim_emitted++;
+   }
+
+   if (!stage->draw->feedback.discard)
+      stage->next->point( stage->next, header );
+}
+
+
+static void feedback_end( struct draw_stage *stage )
+{
+
+   /* XXX Unmap the vertex feedback buffers so we can write to them */
+
+
+   if (!stage->draw->feedback.discard)
+      stage->next->end( stage->next );
+}
+
+
+
+static void feedback_reset_stipple_counter( struct draw_stage *stage )
+{
+   if (!stage->draw->feedback.discard)
+      stage->next->reset_stipple_counter( stage->next );
+}
+
+
+/**
+ * Create feedback drawing stage.
+ */
+struct draw_stage *draw_feedback_stage( struct draw_context *draw )
+{
+   struct feedback_stage *feedback = CALLOC_STRUCT(feedback_stage);
+
+   feedback->stage.draw = draw;
+   feedback->stage.next = NULL;
+   feedback->stage.begin = feedback_begin;
+   feedback->stage.point = feedback_point;
+   feedback->stage.line = feedback_line;
+   feedback->stage.tri = feedback_tri;
+   feedback->stage.end = feedback_end;
+   feedback->stage.reset_stipple_counter = feedback_reset_stipple_counter;
+
+   return &feedback->stage;
+}
+
+