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
30#include "main/mtypes.h"
31#include "main/macros.h"
32#include "main/enums.h"
33#include "vbo/vbo.h"
34
35#include "t_split.h"
36
37
38#define MAX_PRIM 32
39
40/* Used for splitting without copying. No attempt is made to handle
41 * too large indexed vertex buffers: In general you need to copy to do
42 * that.
43 */
44struct split_context {
45   struct gl_context *ctx;
46   const struct tnl_vertex_array *array;
47   const struct _mesa_prim *prim;
48   GLuint nr_prims;
49   const struct _mesa_index_buffer *ib;
50   GLuint min_index;
51   GLuint max_index;
52   GLuint num_instances;
53   GLuint base_instance;
54   tnl_draw_func draw;
55
56   const struct split_limits *limits;
57   GLuint limit;
58
59   struct _mesa_prim dstprim[MAX_PRIM];
60   GLuint dstprim_nr;
61};
62
63
64
65
66static void
67flush_vertex( struct split_context *split)
68{
69   struct gl_context *ctx = split->ctx;
70   struct _mesa_index_buffer ib;
71   GLuint i;
72
73   if (!split->dstprim_nr)
74      return;
75
76   if (split->ib) {
77      ib = *split->ib;
78
79      ib.count = split->max_index - split->min_index + 1;
80      ib.ptr = (const void *)((const char *)ib.ptr +
81                              (split->min_index << ib.index_size_shift));
82
83      /* Rebase the primitives to save index buffer entries. */
84      for (i = 0; i < split->dstprim_nr; i++)
85         split->dstprim[i].start -= split->min_index;
86   }
87
88   assert(split->max_index >= split->min_index);
89
90   split->draw(ctx,
91               split->array,
92               split->dstprim,
93               split->dstprim_nr,
94               split->ib ? &ib : NULL,
95               !split->ib,
96               split->min_index,
97               split->max_index,
98               split->num_instances,
99               split->base_instance);
100
101   split->dstprim_nr = 0;
102   split->min_index = ~0;
103   split->max_index = 0;
104}
105
106
107static struct _mesa_prim *
108next_outprim(struct split_context *split)
109{
110   if (split->dstprim_nr == MAX_PRIM-1) {
111      flush_vertex(split);
112   }
113
114   {
115      struct _mesa_prim *prim = &split->dstprim[split->dstprim_nr++];
116      memset(prim, 0, sizeof(*prim));
117      return prim;
118   }
119}
120
121
122static void
123update_index_bounds(struct split_context *split,
124                    const struct _mesa_prim *prim)
125{
126   split->min_index = MIN2(split->min_index, prim->start);
127   split->max_index = MAX2(split->max_index, prim->start + prim->count - 1);
128}
129
130
131/* Return the maximum amount of vertices that can be emitted for a
132 * primitive starting at 'prim->start', depending on the previous
133 * index bounds.
134 */
135static GLuint
136get_max_vertices(struct split_context *split,
137                 const struct _mesa_prim *prim)
138{
139   if ((prim->start > split->min_index &&
140        prim->start - split->min_index >= split->limit) ||
141       (prim->start < split->max_index &&
142        split->max_index - prim->start >= split->limit))
143      /* "prim" starts too far away from the old range. */
144      return 0;
145
146   return MIN2(split->min_index, prim->start) + split->limit - prim->start;
147}
148
149
150/* Break large primitives into smaller ones.  If not possible, convert
151 * the primitive to indexed and pass to split_elts().
152 */
153static void
154split_prims(struct split_context *split)
155{
156   GLuint i;
157
158   for (i = 0; i < split->nr_prims; i++) {
159      const struct _mesa_prim *prim = &split->prim[i];
160      GLuint first, incr;
161      GLboolean split_inplace =
162         _tnl_split_prim_inplace(prim->mode, &first, &incr);
163      GLuint available = get_max_vertices(split, prim);
164      GLuint count = prim->count - (prim->count - first) % incr;
165
166      if (prim->count < first)
167         continue;
168
169      if ((available < count && !split_inplace) ||
170          (available < first && split_inplace)) {
171         flush_vertex(split);
172         available = get_max_vertices(split, prim);
173      }
174
175      if (available >= count) {
176         struct _mesa_prim *outprim = next_outprim(split);
177
178         *outprim = *prim;
179         update_index_bounds(split, outprim);
180      }
181      else if (split_inplace) {
182         GLuint j, nr;
183
184         for (j = 0 ; j < count ;) {
185            GLuint remaining = count - j;
186            struct _mesa_prim *outprim = next_outprim(split);
187
188            nr = MIN2(available, remaining);
189            nr -= (nr - first) % incr;
190
191            outprim->mode = prim->mode;
192            outprim->begin = (j == 0 && prim->begin);
193            outprim->end = (nr == remaining && prim->end);
194            outprim->start = prim->start + j;
195            outprim->count = nr;
196
197            update_index_bounds(split, outprim);
198
199            if (nr == remaining) {
200               /* Finished */
201               j += nr;
202            }
203            else {
204               /* Wrapped the primitive */
205               j += nr - (first - incr);
206               flush_vertex(split);
207               available = get_max_vertices(split, prim);
208            }
209         }
210      }
211      else if (split->ib == NULL) {
212         /* XXX: could at least send the first max_verts off from the
213          * inplace buffers.
214          */
215
216         /* else convert to indexed primitive and pass to split_elts,
217          * which will do the necessary copying and turn it back into a
218          * vertex primitive for rendering...
219          */
220         struct _mesa_index_buffer ib;
221         struct _mesa_prim tmpprim;
222         GLuint *elts = malloc(count * sizeof(GLuint));
223         GLuint j;
224
225         for (j = 0; j < count; j++)
226            elts[j] = prim->start + j;
227
228         ib.count = count;
229         ib.index_size_shift = 2;
230         ib.obj = NULL;
231         ib.ptr = elts;
232
233         tmpprim = *prim;
234         tmpprim.start = 0;
235         tmpprim.count = count;
236
237         flush_vertex(split);
238
239         _tnl_split_copy(split->ctx,
240                         split->array,
241                         &tmpprim, 1,
242                         &ib,
243                         split->draw,
244                         split->limits);
245
246         free(elts);
247      }
248      else {
249         flush_vertex(split);
250
251         _tnl_split_copy(split->ctx,
252                         split->array,
253                         prim, 1,
254                         split->ib,
255                         split->draw,
256                         split->limits);
257      }
258   }
259
260   flush_vertex(split);
261}
262
263
264void
265_tnl_split_inplace(struct gl_context *ctx,
266                   const struct tnl_vertex_array *arrays,
267                   const struct _mesa_prim *prim,
268                   GLuint nr_prims,
269                   const struct _mesa_index_buffer *ib,
270                   GLuint num_instances,
271                   GLuint base_instance,
272                   tnl_draw_func draw,
273                   const struct split_limits *limits)
274{
275   struct split_context split;
276
277   memset(&split, 0, sizeof(split));
278
279   split.ctx = ctx;
280   split.array = arrays;
281   split.prim = prim;
282   split.nr_prims = nr_prims;
283   split.ib = ib;
284
285   /* Empty interval, makes calculations simpler. */
286   split.min_index = ~0;
287   split.max_index = 0;
288   split.num_instances = num_instances;
289   split.base_instance = base_instance;
290
291   split.draw = draw;
292   split.limits = limits;
293   split.limit = ib ? limits->max_indices : limits->max_verts;
294
295   split_prims(&split);
296}
297