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/imports.h"
  32 #include "main/bufferobj.h"
  33 #include "main/macros.h"
  34 #include "main/varray.h"
  35
  36 #include "vbo.h"
  37 #include "vbo_private.h"
  38
  39
  40 #define UPDATE_MIN2(a, b) (a) = MIN2((a), (b))
  41 #define UPDATE_MAX2(a, b) (a) = MAX2((a), (b))
  42
  43 /*
  44  * Notes on primitive restart:
  45  * The code below is used when the driver does not fully support primitive
  46  * restart (for example, if it only does restart index of ~0).
  47  *
  48  * We map the index buffer, find the restart indexes, unmap
  49  * the index buffer then draw the sub-primitives delineated by the restarts.
  50  *
  51  * A couple possible optimizations:
  52  * 1. Save the list of sub-primitive (start, count) values in a list attached
  53  *    to the index buffer for re-use in subsequent draws.  The list would be
  54  *    invalidated when the contents of the buffer changed.
  55  * 2. If drawing triangle strips or quad strips, create a new index buffer
  56  *    that uses duplicated vertices to render the disjoint strips as one
  57  *    long strip.  We'd have to be careful to avoid using too much memory
  58  *    for this.
  59  *
  60  * Finally, some apps might perform better if they don't use primitive restart
  61  * at all rather than this fallback path.  Set MESA_EXTENSION_OVERRIDE to
  62  * "-GL_NV_primitive_restart" to test that.
  63  */
  64
  65
  66 struct sub_primitive
  67 {
  68    GLuint start;
  69    GLuint count;
  70    GLuint min_index;
  71    GLuint max_index;
  72 };
  73
  74
  75 /**
  76  * Scan the elements array to find restart indexes.  Return an array
  77  * of struct sub_primitive to indicate how to draw the sub-primitives
  78  * are delineated by the restart index.
  79  */
  80 static struct sub_primitive *
  81 find_sub_primitives(const void *elements, unsigned element_size,
  82                     unsigned start, unsigned end, unsigned restart_index,
  83                     unsigned *num_sub_prims)
  84 {
  85    const unsigned max_prims = end - start;
  86    struct sub_primitive *sub_prims;
  87    unsigned i, cur_start, cur_count;
  88    GLuint scan_index;
  89    unsigned scan_num;
  90
  91    sub_prims =
  92       malloc(max_prims * sizeof(struct sub_primitive));
  93
  94    if (!sub_prims) {
  95       *num_sub_prims = 0;
  96       return NULL;
  97    }
  98
  99    cur_start = start;
 100    cur_count = 0;
 101    scan_num = 0;
 102
 103 #define IB_INDEX_READ(TYPE, INDEX) (((const GL##TYPE *) elements)[INDEX])
 104
 105 #define SCAN_ELEMENTS(TYPE) \
 106    sub_prims[scan_num].min_index = (GL##TYPE) 0xffffffff; \
 107    sub_prims[scan_num].max_index = 0; \
 108    for (i = start; i < end; i++) { \
 109       scan_index = IB_INDEX_READ(TYPE, i); \
 110       if (scan_index == restart_index) { \
 111          if (cur_count > 0) { \
 112             assert(scan_num < max_prims); \
 113             sub_prims[scan_num].start = cur_start; \
 114             sub_prims[scan_num].count = cur_count; \
 115             scan_num++; \
 116             sub_prims[scan_num].min_index = (GL##TYPE) 0xffffffff; \
 117             sub_prims[scan_num].max_index = 0; \
 118          } \
 119          cur_start = i + 1; \
 120          cur_count = 0; \
 121       } \
 122       else { \
 123          UPDATE_MIN2(sub_prims[scan_num].min_index, scan_index); \
 124          UPDATE_MAX2(sub_prims[scan_num].max_index, scan_index); \
 125          cur_count++; \
 126       } \
 127    } \
 128    if (cur_count > 0) { \
 129       assert(scan_num < max_prims); \
 130       sub_prims[scan_num].start = cur_start; \
 131       sub_prims[scan_num].count = cur_count; \
 132       scan_num++; \
 133    }
 134
 135    switch (element_size) {
 136    case 1:
 137       SCAN_ELEMENTS(ubyte);
 138       break;
 139    case 2:
 140       SCAN_ELEMENTS(ushort);
 141       break;
 142    case 4:
 143       SCAN_ELEMENTS(uint);
 144       break;
 145    default:
 146       assert(0 && "bad index_size in find_sub_primitives()");
 147    }
 148
 149 #undef SCAN_ELEMENTS
 150
 151    *num_sub_prims = scan_num;
 152
 153    return sub_prims;
 154 }
 155
 156
 157 /**
 158  * Handle primitive restart in software.
 159  *
 160  * This function breaks up calls into the driver so primitive restart
 161  * support is not required in the driver.
 162  */
 163 void
 164 vbo_sw_primitive_restart(struct gl_context *ctx,
 165                          const struct _mesa_prim *prims,
 166                          GLuint nr_prims,
 167                          const struct _mesa_index_buffer *ib,
 168                          struct gl_buffer_object *indirect)
 169 {
 170    GLuint prim_num;
 171    struct _mesa_prim new_prim;
 172    struct _mesa_index_buffer new_ib;
 173    struct sub_primitive *sub_prims;
 174    struct sub_primitive *sub_prim;
 175    GLuint num_sub_prims;
 176    GLuint sub_prim_num;
 177    GLuint end_index;
 178    GLuint sub_end_index;
 179    GLuint restart_index = _mesa_primitive_restart_index(ctx, ib->index_size);
 180    struct _mesa_prim temp_prim;
 181    struct vbo_context *vbo = vbo_context(ctx);
 182    vbo_draw_func draw_prims_func = vbo->draw_prims;
 183    GLboolean map_ib = ib->obj->Name && !ib->obj->Mappings[MAP_INTERNAL].Pointer;
 184    void *ptr;
 185
 186    /* If there is an indirect buffer, map it and extract the draw params */
 187    if (indirect && prims[0].is_indirect) {
 188       const uint32_t *indirect_params;
 189       if (!ctx->Driver.MapBufferRange(ctx, 0, indirect->Size, GL_MAP_READ_BIT,
 190                                       indirect, MAP_INTERNAL)) {
 191
 192          /* something went wrong with mapping, give up */
 193          _mesa_error(ctx, GL_OUT_OF_MEMORY,
 194                      "failed to map indirect buffer for sw primitive restart");
 195          return;
 196       }
 197
 198       assert(nr_prims == 1);
 199       new_prim = prims[0];
 200       indirect_params = (const uint32_t *)
 201                         ADD_POINTERS(indirect->Mappings[MAP_INTERNAL].Pointer,
 202                                      new_prim.indirect_offset);
 203
 204       new_prim.is_indirect = 0;
 205       new_prim.count = indirect_params[0];
 206       new_prim.num_instances = indirect_params[1];
 207       new_prim.start = indirect_params[2];
 208       new_prim.basevertex = indirect_params[3];
 209       new_prim.base_instance = indirect_params[4];
 210
 211       new_ib = *ib;
 212       new_ib.count = new_prim.count;
 213
 214       prims = &new_prim;
 215       ib = &new_ib;
 216
 217       ctx->Driver.UnmapBuffer(ctx, indirect, MAP_INTERNAL);
 218    }
 219
 220    /* Find the sub-primitives. These are regions in the index buffer which
 221     * are split based on the primitive restart index value.
 222     */
 223    if (map_ib) {
 224       ctx->Driver.MapBufferRange(ctx, 0, ib->obj->Size, GL_MAP_READ_BIT,
 225                                  ib->obj, MAP_INTERNAL);
 226    }
 227
 228    ptr = ADD_POINTERS(ib->obj->Mappings[MAP_INTERNAL].Pointer, ib->ptr);
 229
 230    sub_prims = find_sub_primitives(ptr, ib->index_size,
 231                                    0, ib->count, restart_index,
 232                                    &num_sub_prims);
 233
 234    if (map_ib) {
 235       ctx->Driver.UnmapBuffer(ctx, ib->obj, MAP_INTERNAL);
 236    }
 237
 238    /* Loop over the primitives, and use the located sub-primitives to draw
 239     * each primitive with a break to implement each primitive restart.
 240     */
 241    for (prim_num = 0; prim_num < nr_prims; prim_num++) {
 242       end_index = prims[prim_num].start + prims[prim_num].count;
 243       memcpy(&temp_prim, &prims[prim_num], sizeof (temp_prim));
 244       /* Loop over the sub-primitives drawing sub-ranges of the primitive. */
 245       for (sub_prim_num = 0; sub_prim_num < num_sub_prims; sub_prim_num++) {
 246          sub_prim = &sub_prims[sub_prim_num];
 247          sub_end_index = sub_prim->start + sub_prim->count;
 248          if (prims[prim_num].start <= sub_prim->start) {
 249             temp_prim.start = MAX2(prims[prim_num].start, sub_prim->start);
 250             temp_prim.count = MIN2(sub_end_index, end_index) - temp_prim.start;
 251             if ((temp_prim.start == sub_prim->start) &&
 252                 (temp_prim.count == sub_prim->count)) {
 253                draw_prims_func(ctx, &temp_prim, 1, ib,
 254                                GL_TRUE, sub_prim->min_index, sub_prim->max_index,
 255                                NULL, 0, NULL);
 256             } else {
 257                draw_prims_func(ctx, &temp_prim, 1, ib,
 258                                GL_FALSE, -1, -1,
 259                                NULL, 0, NULL);
 260             }
 261          }
 262          if (sub_end_index >= end_index) {
 263             break;
 264          }
 265       }
 266    }
 267
 268    free(sub_prims);
 269 }
 270