1
2/*
3 * Mesa 3-D graphics library
4 *
5 * Copyright (C) 1999-2006  Brian Paul   All Rights Reserved.
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a
8 * copy of this software and associated documentation files (the "Software"),
9 * to deal in the Software without restriction, including without limitation
10 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
11 * and/or sell copies of the Software, and to permit persons to whom the
12 * Software is furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included
15 * in all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
18 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
21 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
22 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
23 * OTHER DEALINGS IN THE SOFTWARE.
24 *
25 * Authors:
26 *    Keith Whitwell <keithw@vmware.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/mtypes.h"
52#include "vbo/vbo.h"
53
54#include "t_split.h"
55
56
57/* True if a primitive can be split without copying of vertices, false
58 * otherwise.
59 */
60GLboolean
61_tnl_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
102_tnl_split_prims(struct gl_context *ctx,
103                 const struct tnl_vertex_array arrays[],
104                 const struct _mesa_prim *prim,
105                 GLuint nr_prims,
106                 const struct _mesa_index_buffer *ib,
107                 GLuint min_index,
108                 GLuint max_index,
109                 tnl_draw_func draw,
110                 const struct split_limits *limits)
111{
112   if (ib) {
113      if (limits->max_indices == 0) {
114         /* Could traverse the indices, re-emitting vertices in turn.
115          * But it's hard to see why this case would be needed - for
116          * software tnl, it is better to convert to non-indexed
117          * rendering after transformation is complete.  Are there any devices
118          * with hardware tnl that cannot do indexed rendering?
119          *
120          * For now, this path is disabled.
121          */
122         assert(0);
123      }
124      else if (max_index - min_index >= limits->max_verts) {
125         /* The vertex buffers are too large for hardware (or the
126          * swtnl module).  Traverse the indices, re-emitting vertices
127          * in turn.  Use a vertex cache to preserve some of the
128          * sharing from the original index list.
129          */
130         _tnl_split_copy(ctx, arrays, prim, nr_prims, ib, draw, limits);
131      }
132      else if (ib->count > limits->max_indices) {
133         /* The index buffer is too large for hardware.  Try to split
134          * on whole-primitive boundaries, otherwise try to split the
135          * individual primitives.
136          */
137         _tnl_split_inplace(ctx, arrays, prim, nr_prims, ib,
138                            min_index, max_index, draw, limits);
139      }
140      else {
141         /* Why were we called? */
142         assert(0);
143      }
144   }
145   else {
146      if (max_index - min_index >= limits->max_verts) {
147         /* The vertex buffer is too large for hardware (or the swtnl
148          * module).  Try to split on whole-primitive boundaries,
149          * otherwise try to split the individual primitives.
150          */
151         _tnl_split_inplace(ctx, arrays, prim, nr_prims, ib,
152                            min_index, max_index, draw, limits);
153      }
154      else {
155         /* Why were we called? */
156         assert(0);
157      }
158   }
159}
160
161