Helper for rebasing draw requests where min_index != 0.

1 files changed, 221 insertions, 0 deletions

diff --git a/src/mesa/vbo/vbo_rebase.c b/src/mesa/vbo/vbo_rebase.c
new file mode 100644
index 0000000000..2a6f03797a
--- /dev/null
+++ b/src/mesa/vbo/vbo_rebase.c
@@ -0,0 +1,221 @@
+
+/*
+ * Mesa 3-D graphics library
+ * Version:  6.5
+ *
+ * Copyright (C) 1999-2006  Brian Paul   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, sublicense,
+ * 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 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 NONINFRINGEMENT.  IN NO EVENT SHALL
+ * BRIAN PAUL 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.
+ *
+ * Authors:
+ *    Keith Whitwell <keith@tungstengraphics.com>
+ */
+
+/* Helper for drivers which find themselves rendering a range of
+ * indices starting somewhere above zero.  Typically the application
+ * is issuing multiple DrawArrays() or DrawElements() to draw
+ * successive primitives layed out linearly in the vertex arrays.
+ * Unless the vertex arrays are all in a VBO, the OpenGL semantics
+ * imply that we need to re-upload the vertex data on each draw call.
+ * In that case, we want to avoid starting the upload at zero, as it
+ * will mean every draw call uploads an increasing amount of not-used
+ * vertex data.  Worse - in the software tnl module, all those
+ * vertices will be transformed and lit.
+ *
+ * If we just upload the new data, however, the indices will be
+ * incorrect as we tend to upload each set of vertex data to a new
+ * region.  
+ *
+ * This file provides a helper to adjust the arrays, primitives and
+ * indices of a draw call so that it can be re-issued with a min_index
+ * of zero.
+ */
+
+#include "glheader.h"
+#include "imports.h"
+#include "mtypes.h"
+
+#include "vbo.h"
+
+
+#define REBASE(TYPE) 						\
+static void *rebase_##TYPE( const void *ptr,			\
+			  GLuint count, 			\
+			  TYPE min_index )			\
+{								\
+   const TYPE *in = (TYPE *)ptr;				\
+   TYPE *tmp_indices = malloc(count * sizeof(TYPE));	\
+   GLuint i;							\
+								\
+   for (i = 0; i < count; i++)  				\
+      tmp_indices[i] = in[i] - min_index;			\
+								\
+   return (void *)tmp_indices;					\
+}
+
+
+REBASE(GLuint)
+REBASE(GLushort)
+REBASE(GLubyte)
+
+GLboolean vbo_all_varyings_in_vbos( const struct gl_client_array *arrays[] )
+{
+   GLuint i;
+   
+   for (i = 0; i < VERT_ATTRIB_MAX; i++)
+      if (arrays[i]->StrideB &&
+	  arrays[i]->BufferObj->Name == 0)
+	 return GL_FALSE;
+
+   return GL_TRUE;
+}
+
+/* Adjust primitives, indices and vertex definitions so that min_index
+ * becomes zero. There are lots of reasons for wanting to do this, eg:
+ *
+ * Software tnl:
+ *    - any time min_index != 0, otherwise unused vertices lower than
+ *      min_index will be transformed.
+ *
+ * Hardware tnl:
+ *    - if ib != NULL and min_index != 0, otherwise vertices lower than 
+ *      min_index will be uploaded.  Requires adjusting index values.
+ *
+ *    - if ib == NULL and min_index != 0, just for convenience so this doesn't
+ *      have to be handled within the driver.
+ *
+ * Hardware tnl with VBO support:
+ *    - as above, but only when vertices are not (all?) in VBO's.
+ *    - can't save time by trying to upload half a vbo - typically it is
+ *      all or nothing.
+ */
+void vbo_rebase_prims( GLcontext *ctx,
+		       const struct gl_client_array *arrays[],
+		       const struct _mesa_prim *prim,
+		       GLuint nr_prims,
+		       const struct _mesa_index_buffer *ib,
+		       GLuint min_index,
+		       GLuint max_index,
+		       vbo_draw_func draw )
+{
+   struct gl_client_array tmp_arrays[VERT_ATTRIB_MAX];
+   const struct gl_client_array *tmp_array_pointers[VERT_ATTRIB_MAX];
+
+   struct _mesa_index_buffer tmp_ib;
+   struct _mesa_prim *tmp_prims = NULL;
+   void *tmp_indices = NULL;
+   GLuint i;
+
+   assert(min_index != 0);
+
+   _mesa_printf("%s %d..%d\n", __FUNCTION__, min_index, max_index);
+
+   if (ib) {
+      /* Unfortunately need to adjust each index individually.
+       */
+      GLboolean map_ib = ib->obj->Name && !ib->obj->Pointer;
+      void *ptr;
+
+      if (map_ib) 
+	 ctx->Driver.MapBuffer(ctx, 
+			       GL_ELEMENT_ARRAY_BUFFER,
+			       GL_READ_ONLY_ARB,
+			       ib->obj);
+
+
+      ptr = ADD_POINTERS(ib->obj->Pointer, ib->ptr);
+
+      /* Some users might prefer it if we translated elements to
+       * GLuints here.  Others wouldn't...
+       */
+      switch (ib->type) {
+      case GL_UNSIGNED_INT: 
+	 tmp_indices = rebase_GLuint( ptr, ib->count, min_index );
+	 break;
+      case GL_UNSIGNED_SHORT: 
+	 tmp_indices = rebase_GLushort( ptr, ib->count, min_index );
+	 break;
+      case GL_UNSIGNED_BYTE: 
+	 tmp_indices = rebase_GLubyte( ptr, ib->count, min_index );
+	 break;
+      }      
+
+      if (map_ib) 
+	 ctx->Driver.UnmapBuffer(ctx, 
+				 GL_ELEMENT_ARRAY_BUFFER,
+				 ib->obj);
+
+      tmp_ib.obj = ctx->Array.NullBufferObj;
+      tmp_ib.ptr = tmp_indices;
+      tmp_ib.count = ib->count;
+      tmp_ib.type = ib->type;
+
+      ib = &tmp_ib;
+   }
+   else {
+      /* Otherwise the primitives need adjustment.
+       */
+      tmp_prims = (struct _mesa_prim *)_mesa_malloc(sizeof(*prim) * nr_prims);
+
+      for (i = 0; i < nr_prims; i++) {
+	 /* If this fails, it could indicate an application error:
+	  */
+	 assert(prim[i].start >= min_index);
+
+	 tmp_prims[i] = prim[i];
+	 tmp_prims[i].start -= min_index;
+      }
+
+      prim = tmp_prims;
+   }
+
+   /* Just need to adjust the pointer values on each incoming array.
+    * This works for VBO and non-vbo rendering and shouldn't pesimize
+    * VBO-based upload schemes.  However this may still not be a fast
+    * path for hardware tnl for VBO based rendering as most machines
+    * will be happier if you just specify a starting vertex value in
+    * each primitive.
+    *
+    * For drivers with hardware tnl, you only want to do this if you
+    * are forced to, eg non-VBO indexed rendering with start != 0.
+    */
+   for (i = 0; i < VERT_ATTRIB_MAX; i++) {
+      tmp_arrays[i] = *arrays[i];
+      tmp_arrays[i].Ptr += min_index * tmp_arrays[i].StrideB;
+      tmp_array_pointers[i] = &tmp_arrays[i];
+   }
+   
+   /* Re-issue the draw call.
+    */
+   draw( ctx, 
+	 tmp_array_pointers, 
+	 prim, 
+	 nr_prims, 
+	 ib, 
+	 0, 
+	 max_index - min_index );
+   
+   if (tmp_indices)
+      _mesa_free(tmp_indices);
+   
+   if (tmp_prims)
+      _mesa_free(tmp_prims);
+}
+
+
+