1
2/*
3 * Mesa 3-D graphics library
4 * Version:  6.5
5 *
6 * Copyright (C) 1999-2006  Brian Paul   All Rights Reserved.
7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a
9 * copy of this software and associated documentation files (the "Software"),
10 * to deal in the Software without restriction, including without limitation
11 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
12 * and/or sell copies of the Software, and to permit persons to whom the
13 * Software is furnished to do so, subject to the following conditions:
14 *
15 * The above copyright notice and this permission notice shall be included
16 * in all copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
19 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
21 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
22 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
23 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
24 *
25 * Authors:
26 *    Keith Whitwell <keith@tungstengraphics.com>
27 */
28
29/* Deal with hardware and/or swtnl maximums:
30 * - maximum number of vertices in buffer
31 * - maximum number of elements (maybe zero)
32 *
33 * The maximums may vary with opengl state (eg if a larger hardware
34 * vertex is required in this state, the maximum number of vertices
35 * may be smaller than in another state).
36 *
37 * We want buffer splitting to be a convenience function for the code
38 * actually drawing the primitives rather than a system-wide maximum,
39 * otherwise it is hard to avoid pessimism.
40 *
41 * For instance, if a driver has no hardware limits on vertex buffer
42 * dimensions, it would not ordinarily want to split vbos.  But if
43 * there is an unexpected fallback, eg memory manager fails to upload
44 * textures, it will want to pass the drawing commands onto swtnl,
45 * which does have limitations.  A convenience function allows swtnl
46 * to split the drawing and vbos internally without imposing its
47 * limitations on drivers which want to use it as a fallback path.
48 */
49
50#include "main/glheader.h"
51#include "main/imports.h"
52#include "main/mtypes.h"
53#include "main/macros.h"
54
55#include "vbo_split.h"
56#include "vbo.h"
57
58/* True if a primitive can be split without copying of vertices, false
59 * otherwise.
60 */
61GLboolean split_prim_inplace(GLenum mode, GLuint *first, GLuint *incr)
62{
63   switch (mode) {
64   case GL_POINTS:
65      *first = 1;
66      *incr = 1;
67      return GL_TRUE;
68   case GL_LINES:
69      *first = 2;
70      *incr = 2;
71      return GL_TRUE;
72   case GL_LINE_STRIP:
73      *first = 2;
74      *incr = 1;
75      return GL_TRUE;
76   case GL_TRIANGLES:
77      *first = 3;
78      *incr = 3;
79      return GL_TRUE;
80   case GL_TRIANGLE_STRIP:
81      *first = 3;
82      *incr = 1;
83      return GL_TRUE;
84   case GL_QUADS:
85      *first = 4;
86      *incr = 4;
87      return GL_TRUE;
88   case GL_QUAD_STRIP:
89      *first = 4;
90      *incr = 2;
91      return GL_TRUE;
92   default:
93      *first = 0;
94      *incr = 1;		/* so that count % incr works */
95      return GL_FALSE;
96   }
97}
98
99
100
101void vbo_split_prims( struct gl_context *ctx,
102		      const struct gl_client_array *arrays[],
103		      const struct _mesa_prim *prim,
104		      GLuint nr_prims,
105		      const struct _mesa_index_buffer *ib,
106		      GLuint min_index,
107		      GLuint max_index,
108		      vbo_draw_func draw,
109		      const struct split_limits *limits )
110{
111   GLint max_basevertex = prim->basevertex;
112   GLuint i;
113
114   for (i = 1; i < nr_prims; i++)
115      max_basevertex = MAX2(max_basevertex, prim[i].basevertex);
116
117   /* XXX max_basevertex is computed but not used, why? */
118
119   if (ib) {
120      if (limits->max_indices == 0) {
121	 /* Could traverse the indices, re-emitting vertices in turn.
122	  * But it's hard to see why this case would be needed - for
123	  * software tnl, it is better to convert to non-indexed
124	  * rendering after transformation is complete.  Are there any devices
125	  * with hardware tnl that cannot do indexed rendering?
126	  *
127	  * For now, this path is disabled.
128	  */
129	 assert(0);
130      }
131      else if (max_index - min_index >= limits->max_verts) {
132	 /* The vertex buffers are too large for hardware (or the
133	  * swtnl module).  Traverse the indices, re-emitting vertices
134	  * in turn.  Use a vertex cache to preserve some of the
135	  * sharing from the original index list.
136	  */
137	 vbo_split_copy(ctx, arrays, prim, nr_prims, ib,
138			draw, limits );
139      }
140      else if (ib->count > limits->max_indices) {
141	 /* The index buffer is too large for hardware.  Try to split
142	  * on whole-primitive boundaries, otherwise try to split the
143	  * individual primitives.
144	  */
145	 vbo_split_inplace(ctx, arrays, prim, nr_prims, ib,
146			   min_index, max_index, draw, limits );
147      }
148      else {
149	 /* Why were we called? */
150	 assert(0);
151      }
152   }
153   else {
154      if (max_index - min_index >= limits->max_verts) {
155	 /* The vertex buffer is too large for hardware (or the swtnl
156	  * module).  Try to split on whole-primitive boundaries,
157	  * otherwise try to split the individual primitives.
158	  */
159	 vbo_split_inplace(ctx, arrays, prim, nr_prims, ib,
160			   min_index, max_index, draw, limits );
161      }
162      else {
163	 /* Why were we called? */
164	 assert(0);
165      }
166   }
167}
168
169