src/mesa/vbo/vbo_primitive_restart.c

   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 "util/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
  65 struct 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  */
  79 static struct sub_primitive *
  80 find_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  */
 162 void
 163 vbo_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                          GLuint num_instances, GLuint base_instance,
 168                          struct gl_buffer_object *indirect,
 169                          GLsizeiptr indirect_offset)
 170 {
 171    GLuint prim_num;
 172    struct _mesa_prim new_prim;
 173    struct _mesa_index_buffer new_ib;
 174    struct sub_primitive *sub_prims;
 175    struct sub_primitive *sub_prim;
 176    GLuint num_sub_prims;
 177    GLuint sub_prim_num;
 178    GLuint end_index;
 179    GLuint sub_end_index;
 180    GLuint restart_index = _mesa_primitive_restart_index(ctx, 1 << ib->index_size_shift);
 181    struct _mesa_prim temp_prim;
 182    GLboolean map_ib = ib->obj->Name && !ib->obj->Mappings[MAP_INTERNAL].Pointer;
 183    void *ptr;
 184
 185    /* If there is an indirect buffer, map it and extract the draw params */
 186    if (indirect) {
 187       const uint32_t *indirect_params;
 188       if (!ctx->Driver.MapBufferRange(ctx, 0, indirect->Size, GL_MAP_READ_BIT,
 189                                       indirect, MAP_INTERNAL)) {
 190
 191          /* something went wrong with mapping, give up */
 192          _mesa_error(ctx, GL_OUT_OF_MEMORY,
 193                      "failed to map indirect buffer for sw primitive restart");
 194          return;
 195       }
 196
 197       assert(nr_prims == 1);
 198       new_prim = prims[0];
 199       indirect_params = (const uint32_t *)
 200                         ADD_POINTERS(indirect->Mappings[MAP_INTERNAL].Pointer,
 201                                      indirect_offset);
 202
 203       new_prim.count = indirect_params[0];
 204       new_prim.start = indirect_params[2];
 205       new_prim.basevertex = indirect_params[3];
 206
 207       num_instances = indirect_params[1];
 208       base_instance = indirect_params[4];
 209
 210       new_ib = *ib;
 211       new_ib.count = new_prim.count;
 212
 213       prims = &new_prim;
 214       ib = &new_ib;
 215
 216       ctx->Driver.UnmapBuffer(ctx, indirect, MAP_INTERNAL);
 217    }
 218
 219    /* Find the sub-primitives. These are regions in the index buffer which
 220     * are split based on the primitive restart index value.
 221     */
 222    if (map_ib) {
 223       ctx->Driver.MapBufferRange(ctx, 0, ib->obj->Size, GL_MAP_READ_BIT,
 224                                  ib->obj, MAP_INTERNAL);
 225    }
 226
 227    ptr = ADD_POINTERS(ib->obj->Mappings[MAP_INTERNAL].Pointer, ib->ptr);
 228
 229    sub_prims = find_sub_primitives(ptr, 1 << ib->index_size_shift,
 230                                    0, ib->count, restart_index,
 231                                    &num_sub_prims);
 232
 233    if (map_ib) {
 234       ctx->Driver.UnmapBuffer(ctx, ib->obj, MAP_INTERNAL);
 235    }
 236
 237    /* Loop over the primitives, and use the located sub-primitives to draw
 238     * each primitive with a break to implement each primitive restart.
 239     */
 240    for (prim_num = 0; prim_num < nr_prims; prim_num++) {
 241       end_index = prims[prim_num].start + prims[prim_num].count;
 242       memcpy(&temp_prim, &prims[prim_num], sizeof (temp_prim));
 243       /* Loop over the sub-primitives drawing sub-ranges of the primitive. */
 244       for (sub_prim_num = 0; sub_prim_num < num_sub_prims; sub_prim_num++) {
 245          sub_prim = &sub_prims[sub_prim_num];
 246          sub_end_index = sub_prim->start + sub_prim->count;
 247          if (prims[prim_num].start <= sub_prim->start) {
 248             temp_prim.start = MAX2(prims[prim_num].start, sub_prim->start);
 249             temp_prim.count = MIN2(sub_end_index, end_index) - temp_prim.start;
 250             if ((temp_prim.start == sub_prim->start) &&
 251                 (temp_prim.count == sub_prim->count)) {
 252                ctx->Driver.Draw(ctx, &temp_prim, 1, ib, GL_TRUE,
 253                                 sub_prim->min_index, sub_prim->max_index,
 254                                 num_instances, base_instance,
 255                                 NULL, 0);
 256             } else {
 257                ctx->Driver.Draw(ctx, &temp_prim, 1, ib,
 258                                 GL_FALSE, -1, -1,
 259                                 num_instances, base_instance,
 260                                 NULL, 0);
 261             }
 262          }
 263          if (sub_end_index >= end_index) {
 264             break;
 265          }
 266       }
 267    }
 268
 269    free(sub_prims);
 270 }
 271