1/*
2 * Copyright 2007 VMware, Inc.
3 * All Rights Reserved.
4 *
5 * Copyright © 2012 Intel Corporation
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 (including the next
15 * paragraph) shall be included in all copies or substantial portions of the
16 * Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
21 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
23 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
24 * IN THE SOFTWARE.
25 *
26 * Authors:
27 *    Jordan Justen <jordan.l.justen@intel.com>
28 *
29 */
30
31#include "main/errors.h"
32#include "main/imports.h"
33#include "main/macros.h"
34#include "main/varray.h"
35
36#include "vbo.h"
37
38
39#define UPDATE_MIN2(a, b) (a) = MIN2((a), (b))
40#define UPDATE_MAX2(a, b) (a) = MAX2((a), (b))
41
42/*
43 * Notes on primitive restart:
44 * The code below is used when the driver does not fully support primitive
45 * restart (for example, if it only does restart index of ~0).
46 *
47 * We map the index buffer, find the restart indexes, unmap
48 * the index buffer then draw the sub-primitives delineated by the restarts.
49 *
50 * A couple possible optimizations:
51 * 1. Save the list of sub-primitive (start, count) values in a list attached
52 *    to the index buffer for re-use in subsequent draws.  The list would be
53 *    invalidated when the contents of the buffer changed.
54 * 2. If drawing triangle strips or quad strips, create a new index buffer
55 *    that uses duplicated vertices to render the disjoint strips as one
56 *    long strip.  We'd have to be careful to avoid using too much memory
57 *    for this.
58 *
59 * Finally, some apps might perform better if they don't use primitive restart
60 * at all rather than this fallback path.  Set MESA_EXTENSION_OVERRIDE to
61 * "-GL_NV_primitive_restart" to test that.
62 */
63
64
65struct sub_primitive
66{
67   GLuint start;
68   GLuint count;
69   GLuint min_index;
70   GLuint max_index;
71};
72
73
74/**
75 * Scan the elements array to find restart indexes.  Return an array
76 * of struct sub_primitive to indicate how to draw the sub-primitives
77 * are delineated by the restart index.
78 */
79static struct sub_primitive *
80find_sub_primitives(const void *elements, unsigned element_size,
81                    unsigned start, unsigned end, unsigned restart_index,
82                    unsigned *num_sub_prims)
83{
84   const unsigned max_prims = end - start;
85   struct sub_primitive *sub_prims;
86   unsigned i, cur_start, cur_count;
87   GLuint scan_index;
88   unsigned scan_num;
89
90   sub_prims =
91      malloc(max_prims * sizeof(struct sub_primitive));
92
93   if (!sub_prims) {
94      *num_sub_prims = 0;
95      return NULL;
96   }
97
98   cur_start = start;
99   cur_count = 0;
100   scan_num = 0;
101
102#define IB_INDEX_READ(TYPE, INDEX) (((const GL##TYPE *) elements)[INDEX])
103
104#define SCAN_ELEMENTS(TYPE) \
105   sub_prims[scan_num].min_index = (GL##TYPE) 0xffffffff; \
106   sub_prims[scan_num].max_index = 0; \
107   for (i = start; i < end; i++) { \
108      scan_index = IB_INDEX_READ(TYPE, i); \
109      if (scan_index == restart_index) { \
110         if (cur_count > 0) { \
111            assert(scan_num < max_prims); \
112            sub_prims[scan_num].start = cur_start; \
113            sub_prims[scan_num].count = cur_count; \
114            scan_num++; \
115            sub_prims[scan_num].min_index = (GL##TYPE) 0xffffffff; \
116            sub_prims[scan_num].max_index = 0; \
117         } \
118         cur_start = i + 1; \
119         cur_count = 0; \
120      } \
121      else { \
122         UPDATE_MIN2(sub_prims[scan_num].min_index, scan_index); \
123         UPDATE_MAX2(sub_prims[scan_num].max_index, scan_index); \
124         cur_count++; \
125      } \
126   } \
127   if (cur_count > 0) { \
128      assert(scan_num < max_prims); \
129      sub_prims[scan_num].start = cur_start; \
130      sub_prims[scan_num].count = cur_count; \
131      scan_num++; \
132   }
133
134   switch (element_size) {
135   case 1:
136      SCAN_ELEMENTS(ubyte);
137      break;
138   case 2:
139      SCAN_ELEMENTS(ushort);
140      break;
141   case 4:
142      SCAN_ELEMENTS(uint);
143      break;
144   default:
145      assert(0 && "bad index_size in find_sub_primitives()");
146   }
147
148#undef SCAN_ELEMENTS
149
150   *num_sub_prims = scan_num;
151
152   return sub_prims;
153}
154
155
156/**
157 * Handle primitive restart in software.
158 *
159 * This function breaks up calls into the driver so primitive restart
160 * support is not required in the driver.
161 */
162void
163vbo_sw_primitive_restart(struct gl_context *ctx,
164                         const struct _mesa_prim *prims,
165                         GLuint nr_prims,
166                         const struct _mesa_index_buffer *ib,
167                         struct gl_buffer_object *indirect)
168{
169   GLuint prim_num;
170   struct _mesa_prim new_prim;
171   struct _mesa_index_buffer new_ib;
172   struct sub_primitive *sub_prims;
173   struct sub_primitive *sub_prim;
174   GLuint num_sub_prims;
175   GLuint sub_prim_num;
176   GLuint end_index;
177   GLuint sub_end_index;
178   GLuint restart_index = _mesa_primitive_restart_index(ctx, ib->index_size);
179   struct _mesa_prim temp_prim;
180   GLboolean map_ib = ib->obj->Name && !ib->obj->Mappings[MAP_INTERNAL].Pointer;
181   void *ptr;
182
183   /* If there is an indirect buffer, map it and extract the draw params */
184   if (indirect && prims[0].is_indirect) {
185      const uint32_t *indirect_params;
186      if (!ctx->Driver.MapBufferRange(ctx, 0, indirect->Size, GL_MAP_READ_BIT,
187                                      indirect, MAP_INTERNAL)) {
188
189         /* something went wrong with mapping, give up */
190         _mesa_error(ctx, GL_OUT_OF_MEMORY,
191                     "failed to map indirect buffer for sw primitive restart");
192         return;
193      }
194
195      assert(nr_prims == 1);
196      new_prim = prims[0];
197      indirect_params = (const uint32_t *)
198                        ADD_POINTERS(indirect->Mappings[MAP_INTERNAL].Pointer,
199                                     new_prim.indirect_offset);
200
201      new_prim.is_indirect = 0;
202      new_prim.count = indirect_params[0];
203      new_prim.num_instances = indirect_params[1];
204      new_prim.start = indirect_params[2];
205      new_prim.basevertex = indirect_params[3];
206      new_prim.base_instance = indirect_params[4];
207
208      new_ib = *ib;
209      new_ib.count = new_prim.count;
210
211      prims = &new_prim;
212      ib = &new_ib;
213
214      ctx->Driver.UnmapBuffer(ctx, indirect, MAP_INTERNAL);
215   }
216
217   /* Find the sub-primitives. These are regions in the index buffer which
218    * are split based on the primitive restart index value.
219    */
220   if (map_ib) {
221      ctx->Driver.MapBufferRange(ctx, 0, ib->obj->Size, GL_MAP_READ_BIT,
222                                 ib->obj, MAP_INTERNAL);
223   }
224
225   ptr = ADD_POINTERS(ib->obj->Mappings[MAP_INTERNAL].Pointer, ib->ptr);
226
227   sub_prims = find_sub_primitives(ptr, ib->index_size,
228                                   0, ib->count, restart_index,
229                                   &num_sub_prims);
230
231   if (map_ib) {
232      ctx->Driver.UnmapBuffer(ctx, ib->obj, MAP_INTERNAL);
233   }
234
235   /* Loop over the primitives, and use the located sub-primitives to draw
236    * each primitive with a break to implement each primitive restart.
237    */
238   for (prim_num = 0; prim_num < nr_prims; prim_num++) {
239      end_index = prims[prim_num].start + prims[prim_num].count;
240      memcpy(&temp_prim, &prims[prim_num], sizeof (temp_prim));
241      /* Loop over the sub-primitives drawing sub-ranges of the primitive. */
242      for (sub_prim_num = 0; sub_prim_num < num_sub_prims; sub_prim_num++) {
243         sub_prim = &sub_prims[sub_prim_num];
244         sub_end_index = sub_prim->start + sub_prim->count;
245         if (prims[prim_num].start <= sub_prim->start) {
246            temp_prim.start = MAX2(prims[prim_num].start, sub_prim->start);
247            temp_prim.count = MIN2(sub_end_index, end_index) - temp_prim.start;
248            if ((temp_prim.start == sub_prim->start) &&
249                (temp_prim.count == sub_prim->count)) {
250               ctx->Driver.Draw(ctx, &temp_prim, 1, ib, GL_TRUE,
251                                sub_prim->min_index, sub_prim->max_index,
252                                NULL, 0, NULL);
253            } else {
254               ctx->Driver.Draw(ctx, &temp_prim, 1, ib,
255                                GL_FALSE, -1, -1,
256                                NULL, 0, NULL);
257            }
258         }
259         if (sub_end_index >= end_index) {
260            break;
261         }
262      }
263   }
264
265   free(sub_prims);
266}
267
268