src/mesa/main/arrayobj.c

   1 /*
   2  * Mesa 3-D graphics library
   3  *
   4  * Copyright (C) 1999-2008  Brian Paul   All Rights Reserved.
   5  * (C) Copyright IBM Corporation 2006
   6  * Copyright (C) 2009  VMware, Inc.  All Rights Reserved.
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a
   9  * copy of this software and associated documentation files (the "Software"),
  10  * to deal in the Software without restriction, including without limitation
  11  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  12  * and/or sell copies of the Software, and to permit persons to whom the
  13  * Software is furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included
  16  * in all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  19  * OR 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
  22  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  23  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  24  * OTHER DEALINGS IN THE SOFTWARE.
  25  */
  26
  27
  28 /**
  29  * \file arrayobj.c
  30  *
  31  * Implementation of Vertex Array Objects (VAOs), from OpenGL 3.1+,
  32  * the GL_ARB_vertex_array_object extension, or the older
  33  * GL_APPLE_vertex_array_object extension.
  34  *
  35  * \todo
  36  * The code in this file borrows a lot from bufferobj.c.  There's a certain
  37  * amount of cruft left over from that origin that may be unnecessary.
  38  *
  39  * \author Ian Romanick <idr@us.ibm.com>
  40  * \author Brian Paul
  41  */
  42
  43
  44 #include "glheader.h"
  45 #include "hash.h"
  46 #include "image.h"
  47 #include "imports.h"
  48 #include "context.h"
  49 #include "bufferobj.h"
  50 #include "arrayobj.h"
  51 #include "macros.h"
  52 #include "mtypes.h"
  53 #include "varray.h"
  54 #include "main/dispatch.h"
  55
  56
  57 /**
  58  * Look up the array object for the given ID.
  59  *
  60  * \returns
  61  * Either a pointer to the array object with the specified ID or \c NULL for
  62  * a non-existent ID.  The spec defines ID 0 as being technically
  63  * non-existent.
  64  */
  65
  66 struct gl_vertex_array_object *
  67 _mesa_lookup_vao(struct gl_context *ctx, GLuint id)
  68 {
  69    if (id == 0)
  70       return NULL;
  71    else
  72       return (struct gl_vertex_array_object *)
  73          _mesa_HashLookup(ctx->Array.Objects, id);
  74 }
  75
  76
  77 /**
  78  * Looks up the array object for the given ID.
  79  *
  80  * Unlike _mesa_lookup_vao, this function generates a GL_INVALID_OPERATION
  81  * error if the array object does not exist. It also returns the default
  82  * array object when ctx is a compatibility profile context and id is zero.
  83  */
  84 struct gl_vertex_array_object *
  85 _mesa_lookup_vao_err(struct gl_context *ctx, GLuint id, const char *caller)
  86 {
  87    /* The ARB_direct_state_access specification says:
  88     *
  89     *    "<vaobj> is [compatibility profile:
  90     *     zero, indicating the default vertex array object, or]
  91     *     the name of the vertex array object."
  92     */
  93    if (id == 0) {
  94       if (ctx->API == API_OPENGL_CORE) {
  95          _mesa_error(ctx, GL_INVALID_OPERATION,
  96                      "%s(zero is not valid vaobj name in a core profile "
  97                      "context)", caller);
  98          return NULL;
  99       }
 100
 101       return ctx->Array.DefaultVAO;
 102    } else {
 103       struct gl_vertex_array_object *vao;
 104
 105       if (ctx->Array.LastLookedUpVAO &&
 106           ctx->Array.LastLookedUpVAO->Name == id) {
 107          vao = ctx->Array.LastLookedUpVAO;
 108       } else {
 109          vao = (struct gl_vertex_array_object *)
 110             _mesa_HashLookup(ctx->Array.Objects, id);
 111
 112          /* The ARB_direct_state_access specification says:
 113           *
 114           *    "An INVALID_OPERATION error is generated if <vaobj> is not
 115           *     [compatibility profile: zero or] the name of an existing
 116           *     vertex array object."
 117           */
 118          if (!vao || !vao->EverBound) {
 119             _mesa_error(ctx, GL_INVALID_OPERATION,
 120                         "%s(non-existent vaobj=%u)", caller, id);
 121             return NULL;
 122          }
 123
 124          _mesa_reference_vao(ctx, &ctx->Array.LastLookedUpVAO, vao);
 125       }
 126
 127       return vao;
 128    }
 129 }
 130
 131
 132 /**
 133  * For all the vertex binding points in the array object, unbind any pointers
 134  * to any buffer objects (VBOs).
 135  * This is done just prior to array object destruction.
 136  */
 137 static void
 138 unbind_array_object_vbos(struct gl_context *ctx, struct gl_vertex_array_object *obj)
 139 {
 140    GLuint i;
 141
 142    for (i = 0; i < ARRAY_SIZE(obj->VertexBinding); i++)
 143       _mesa_reference_buffer_object(ctx, &obj->VertexBinding[i].BufferObj, NULL);
 144
 145    for (i = 0; i < ARRAY_SIZE(obj->_VertexAttrib); i++)
 146       _mesa_reference_buffer_object(ctx, &obj->_VertexAttrib[i].BufferObj, NULL);
 147 }
 148
 149
 150 /**
 151  * Allocate and initialize a new vertex array object.
 152  *
 153  * This function is intended to be called via
 154  */
 155 struct gl_vertex_array_object *
 156 _mesa_new_vao(struct gl_context *ctx, GLuint name)
 157 {
 158    struct gl_vertex_array_object *obj = CALLOC_STRUCT(gl_vertex_array_object);
 159    if (obj)
 160       _mesa_initialize_vao(ctx, obj, name);
 161    return obj;
 162 }
 163
 164
 165 /**
 166  * Delete an array object.
 167  *
 168  * This function is intended to be called via
 169  * \c dd_function_table::DeleteArrayObject.
 170  */
 171 void
 172 _mesa_delete_vao(struct gl_context *ctx, struct gl_vertex_array_object *obj)
 173 {
 174    unbind_array_object_vbos(ctx, obj);
 175    _mesa_reference_buffer_object(ctx, &obj->IndexBufferObj, NULL);
 176    mtx_destroy(&obj->Mutex);
 177    free(obj->Label);
 178    free(obj);
 179 }
 180
 181
 182 /**
 183  * Set ptr to vao w/ reference counting.
 184  * Note: this should only be called from the _mesa_reference_vao()
 185  * inline function.
 186  */
 187 void
 188 _mesa_reference_vao_(struct gl_context *ctx,
 189                      struct gl_vertex_array_object **ptr,
 190                      struct gl_vertex_array_object *vao)
 191 {
 192    assert(*ptr != vao);
 193
 194    if (*ptr) {
 195       /* Unreference the old array object */
 196       GLboolean deleteFlag = GL_FALSE;
 197       struct gl_vertex_array_object *oldObj = *ptr;
 198
 199       mtx_lock(&oldObj->Mutex);
 200       assert(oldObj->RefCount > 0);
 201       oldObj->RefCount--;
 202       deleteFlag = (oldObj->RefCount == 0);
 203       mtx_unlock(&oldObj->Mutex);
 204
 205       if (deleteFlag) {
 206          assert(ctx->Driver.DeleteArrayObject);
 207          ctx->Driver.DeleteArrayObject(ctx, oldObj);
 208       }
 209
 210       *ptr = NULL;
 211    }
 212    assert(!*ptr);
 213
 214    if (vao) {
 215       /* reference new array object */
 216       mtx_lock(&vao->Mutex);
 217       if (vao->RefCount == 0) {
 218          /* this array's being deleted (look just above) */
 219          /* Not sure this can every really happen.  Warn if it does. */
 220          _mesa_problem(NULL, "referencing deleted array object");
 221          *ptr = NULL;
 222       }
 223       else {
 224          vao->RefCount++;
 225          *ptr = vao;
 226       }
 227       mtx_unlock(&vao->Mutex);
 228    }
 229 }
 230
 231
 232
 233 static void
 234 init_array(struct gl_context *ctx,
 235            struct gl_vertex_array_object *obj, GLuint index, GLint size, GLint type)
 236 {
 237    struct gl_vertex_attrib_array *array = &obj->VertexAttrib[index];
 238    struct gl_vertex_buffer_binding *binding = &obj->VertexBinding[index];
 239
 240    array->Size = size;
 241    array->Type = type;
 242    array->Format = GL_RGBA; /* only significant for GL_EXT_vertex_array_bgra */
 243    array->Stride = 0;
 244    array->Ptr = NULL;
 245    array->RelativeOffset = 0;
 246    array->Enabled = GL_FALSE;
 247    array->Normalized = GL_FALSE;
 248    array->Integer = GL_FALSE;
 249    array->Doubles = GL_FALSE;
 250    array->_ElementSize = size * _mesa_sizeof_type(type);
 251    array->VertexBinding = index;
 252
 253    binding->Offset = 0;
 254    binding->Stride = array->_ElementSize;
 255    binding->BufferObj = NULL;
 256    binding->_BoundArrays = BITFIELD64_BIT(index);
 257
 258    /* Vertex array buffers */
 259    _mesa_reference_buffer_object(ctx, &binding->BufferObj,
 260                                  ctx->Shared->NullBufferObj);
 261 }
 262
 263
 264 /**
 265  * Initialize a gl_vertex_array_object's arrays.
 266  */
 267 void
 268 _mesa_initialize_vao(struct gl_context *ctx,
 269                      struct gl_vertex_array_object *obj,
 270                      GLuint name)
 271 {
 272    GLuint i;
 273
 274    obj->Name = name;
 275
 276    mtx_init(&obj->Mutex, mtx_plain);
 277    obj->RefCount = 1;
 278
 279    /* Init the individual arrays */
 280    for (i = 0; i < ARRAY_SIZE(obj->VertexAttrib); i++) {
 281       switch (i) {
 282       case VERT_ATTRIB_WEIGHT:
 283          init_array(ctx, obj, VERT_ATTRIB_WEIGHT, 1, GL_FLOAT);
 284          break;
 285       case VERT_ATTRIB_NORMAL:
 286          init_array(ctx, obj, VERT_ATTRIB_NORMAL, 3, GL_FLOAT);
 287          break;
 288       case VERT_ATTRIB_COLOR1:
 289          init_array(ctx, obj, VERT_ATTRIB_COLOR1, 3, GL_FLOAT);
 290          break;
 291       case VERT_ATTRIB_FOG:
 292          init_array(ctx, obj, VERT_ATTRIB_FOG, 1, GL_FLOAT);
 293          break;
 294       case VERT_ATTRIB_COLOR_INDEX:
 295          init_array(ctx, obj, VERT_ATTRIB_COLOR_INDEX, 1, GL_FLOAT);
 296          break;
 297       case VERT_ATTRIB_EDGEFLAG:
 298          init_array(ctx, obj, VERT_ATTRIB_EDGEFLAG, 1, GL_BOOL);
 299          break;
 300       case VERT_ATTRIB_POINT_SIZE:
 301          init_array(ctx, obj, VERT_ATTRIB_POINT_SIZE, 1, GL_FLOAT);
 302          break;
 303       default:
 304          init_array(ctx, obj, i, 4, GL_FLOAT);
 305          break;
 306       }
 307    }
 308
 309    _mesa_reference_buffer_object(ctx, &obj->IndexBufferObj,
 310                                  ctx->Shared->NullBufferObj);
 311 }
 312
 313
 314 /**
 315  * Add the given array object to the array object pool.
 316  */
 317 static void
 318 save_array_object( struct gl_context *ctx, struct gl_vertex_array_object *obj )
 319 {
 320    if (obj->Name > 0) {
 321       /* insert into hash table */
 322       _mesa_HashInsert(ctx->Array.Objects, obj->Name, obj);
 323    }
 324 }
 325
 326
 327 /**
 328  * Remove the given array object from the array object pool.
 329  * Do not deallocate the array object though.
 330  */
 331 static void
 332 remove_array_object( struct gl_context *ctx, struct gl_vertex_array_object *obj )
 333 {
 334    if (obj->Name > 0) {
 335       /* remove from hash table */
 336       _mesa_HashRemove(ctx->Array.Objects, obj->Name);
 337    }
 338 }
 339
 340
 341 /**
 342  * Updates the derived gl_client_arrays when a gl_vertex_attrib_array
 343  * or a gl_vertex_buffer_binding has changed.
 344  */
 345 void
 346 _mesa_update_vao_client_arrays(struct gl_context *ctx,
 347                                struct gl_vertex_array_object *vao)
 348 {
 349    GLbitfield64 arrays = vao->NewArrays;
 350
 351    while (arrays) {
 352       struct gl_client_array *client_array;
 353       struct gl_vertex_attrib_array *attrib_array;
 354       struct gl_vertex_buffer_binding *buffer_binding;
 355
 356       GLint attrib = ffsll(arrays) - 1;
 357       arrays ^= BITFIELD64_BIT(attrib);
 358
 359       attrib_array = &vao->VertexAttrib[attrib];
 360       buffer_binding = &vao->VertexBinding[attrib_array->VertexBinding];
 361       client_array = &vao->_VertexAttrib[attrib];
 362
 363       _mesa_update_client_array(ctx, client_array, attrib_array,
 364                                 buffer_binding);
 365    }
 366 }
 367
 368
 369 /**********************************************************************/
 370 /* API Functions                                                      */
 371 /**********************************************************************/
 372
 373
 374 /**
 375  * Helper for _mesa_BindVertexArray() and _mesa_BindVertexArrayAPPLE().
 376  * \param genRequired  specifies behavour when id was not generated with
 377  *                     glGenVertexArrays().
 378  */
 379 static void
 380 bind_vertex_array(struct gl_context *ctx, GLuint id, GLboolean genRequired)
 381 {
 382    struct gl_vertex_array_object * const oldObj = ctx->Array.VAO;
 383    struct gl_vertex_array_object *newObj = NULL;
 384
 385    assert(oldObj != NULL);
 386
 387    if ( oldObj->Name == id )
 388       return;   /* rebinding the same array object- no change */
 389
 390    /*
 391     * Get pointer to new array object (newObj)
 392     */
 393    if (id == 0) {
 394       /* The spec says there is no array object named 0, but we use
 395        * one internally because it simplifies things.
 396        */
 397       newObj = ctx->Array.DefaultVAO;
 398    }
 399    else {
 400       /* non-default array object */
 401       newObj = _mesa_lookup_vao(ctx, id);
 402       if (!newObj) {
 403          if (genRequired) {
 404             _mesa_error(ctx, GL_INVALID_OPERATION,
 405                         "glBindVertexArray(non-gen name)");
 406             return;
 407          }
 408
 409          /* For APPLE version, generate a new array object now */
 410          newObj = _mesa_new_vao(ctx, id);
 411          if (!newObj) {
 412             _mesa_error(ctx, GL_OUT_OF_MEMORY, "glBindVertexArrayAPPLE");
 413             return;
 414          }
 415
 416          save_array_object(ctx, newObj);
 417       }
 418
 419       if (!newObj->EverBound) {
 420          /* The "Interactions with APPLE_vertex_array_object" section of the
 421           * GL_ARB_vertex_array_object spec says:
 422           *
 423           *     "The first bind call, either BindVertexArray or
 424           *     BindVertexArrayAPPLE, determines the semantic of the object."
 425           */
 426          newObj->ARBsemantics = genRequired;
 427          newObj->EverBound = GL_TRUE;
 428       }
 429    }
 430
 431    if (ctx->Array.DrawMethod == DRAW_ARRAYS) {
 432       /* The _DrawArrays pointer is pointing at the VAO being unbound and
 433        * that VAO may be in the process of being deleted. If it's not going
 434        * to be deleted, this will have no effect, because the pointer needs
 435        * to be updated by the VBO module anyway.
 436        *
 437        * Before the VBO module can update the pointer, we have to set it
 438        * to NULL for drivers not to set up arrays which are not bound,
 439        * or to prevent a crash if the VAO being unbound is going to be
 440        * deleted.
 441        */
 442       ctx->Array._DrawArrays = NULL;
 443       ctx->Array.DrawMethod = DRAW_NONE;
 444    }
 445
 446    ctx->NewState |= _NEW_ARRAY;
 447    _mesa_reference_vao(ctx, &ctx->Array.VAO, newObj);
 448
 449    /* Pass BindVertexArray call to device driver */
 450    if (ctx->Driver.BindArrayObject && newObj)
 451       ctx->Driver.BindArrayObject(ctx, newObj);
 452 }
 453
 454
 455 /**
 456  * ARB version of glBindVertexArray()
 457  * This function behaves differently from glBindVertexArrayAPPLE() in
 458  * that this function requires all ids to have been previously generated
 459  * by glGenVertexArrays[APPLE]().
 460  */
 461 void GLAPIENTRY
 462 _mesa_BindVertexArray( GLuint id )
 463 {
 464    GET_CURRENT_CONTEXT(ctx);
 465    bind_vertex_array(ctx, id, GL_TRUE);
 466 }
 467
 468
 469 /**
 470  * Bind a new array.
 471  *
 472  * \todo
 473  * The binding could be done more efficiently by comparing the non-NULL
 474  * pointers in the old and new objects.  The only arrays that are "dirty" are
 475  * the ones that are non-NULL in either object.
 476  */
 477 void GLAPIENTRY
 478 _mesa_BindVertexArrayAPPLE( GLuint id )
 479 {
 480    GET_CURRENT_CONTEXT(ctx);
 481    bind_vertex_array(ctx, id, GL_FALSE);
 482 }
 483
 484
 485 /**
 486  * Delete a set of array objects.
 487  *
 488  * \param n      Number of array objects to delete.
 489  * \param ids    Array of \c n array object IDs.
 490  */
 491 void GLAPIENTRY
 492 _mesa_DeleteVertexArrays(GLsizei n, const GLuint *ids)
 493 {
 494    GET_CURRENT_CONTEXT(ctx);
 495    GLsizei i;
 496
 497    if (n < 0) {
 498       _mesa_error(ctx, GL_INVALID_VALUE, "glDeleteVertexArray(n)");
 499       return;
 500    }
 501
 502    for (i = 0; i < n; i++) {
 503       struct gl_vertex_array_object *obj = _mesa_lookup_vao(ctx, ids[i]);
 504
 505       if ( obj != NULL ) {
 506          assert( obj->Name == ids[i] );
 507
 508          /* If the array object is currently bound, the spec says "the binding
 509           * for that object reverts to zero and the default vertex array
 510           * becomes current."
 511           */
 512          if ( obj == ctx->Array.VAO ) {
 513             _mesa_BindVertexArray(0);
 514          }
 515
 516          /* The ID is immediately freed for re-use */
 517          remove_array_object(ctx, obj);
 518
 519          if (ctx->Array.LastLookedUpVAO == obj)
 520             _mesa_reference_vao(ctx, &ctx->Array.LastLookedUpVAO, NULL);
 521
 522          /* Unreference the array object.
 523           * If refcount hits zero, the object will be deleted.
 524           */
 525          _mesa_reference_vao(ctx, &obj, NULL);
 526       }
 527    }
 528 }
 529
 530
 531 /**
 532  * Generate a set of unique array object IDs and store them in \c arrays.
 533  * Helper for _mesa_GenVertexArrays[APPLE]() and _mesa_CreateVertexArrays()
 534  * below.
 535  *
 536  * \param n       Number of IDs to generate.
 537  * \param arrays  Array of \c n locations to store the IDs.
 538  * \param create  Indicates that the objects should also be created.
 539  * \param func    The name of the GL entry point.
 540  */
 541 static void
 542 gen_vertex_arrays(struct gl_context *ctx, GLsizei n, GLuint *arrays,
 543                   bool create, const char *func)
 544 {
 545    GLuint first;
 546    GLint i;
 547
 548    if (n < 0) {
 549       _mesa_error(ctx, GL_INVALID_VALUE, "%s(n < 0)", func);
 550       return;
 551    }
 552
 553    if (!arrays) {
 554       return;
 555    }
 556
 557    first = _mesa_HashFindFreeKeyBlock(ctx->Array.Objects, n);
 558
 559    /* For the sake of simplicity we create the array objects in both
 560     * the Gen* and Create* cases.  The only difference is the value of
 561     * EverBound, which is set to true in the Create* case.
 562     */
 563    for (i = 0; i < n; i++) {
 564       struct gl_vertex_array_object *obj;
 565       GLuint name = first + i;
 566
 567       obj = _mesa_new_vao(ctx, name);
 568       if (!obj) {
 569          _mesa_error(ctx, GL_OUT_OF_MEMORY, "%s", func);
 570          return;
 571       }
 572       obj->EverBound = create;
 573       save_array_object(ctx, obj);
 574       arrays[i] = first + i;
 575    }
 576 }
 577
 578
 579 /**
 580  * ARB version of glGenVertexArrays()
 581  * All arrays will be required to live in VBOs.
 582  */
 583 void GLAPIENTRY
 584 _mesa_GenVertexArrays(GLsizei n, GLuint *arrays)
 585 {
 586    GET_CURRENT_CONTEXT(ctx);
 587    gen_vertex_arrays(ctx, n, arrays, false, "glGenVertexArrays");
 588 }
 589
 590
 591 /**
 592  * APPLE version of glGenVertexArraysAPPLE()
 593  * Arrays may live in VBOs or ordinary memory.
 594  */
 595 void GLAPIENTRY
 596 _mesa_GenVertexArraysAPPLE(GLsizei n, GLuint *arrays)
 597 {
 598    GET_CURRENT_CONTEXT(ctx);
 599    gen_vertex_arrays(ctx, n, arrays, false, "glGenVertexArraysAPPLE");
 600 }
 601
 602
 603 /**
 604  * ARB_direct_state_access
 605  * Generates ID's and creates the array objects.
 606  */
 607 void GLAPIENTRY
 608 _mesa_CreateVertexArrays(GLsizei n, GLuint *arrays)
 609 {
 610    GET_CURRENT_CONTEXT(ctx);
 611    gen_vertex_arrays(ctx, n, arrays, true, "glCreateVertexArrays");
 612 }
 613
 614
 615 /**
 616  * Determine if ID is the name of an array object.
 617  *
 618  * \param id  ID of the potential array object.
 619  * \return  \c GL_TRUE if \c id is the name of a array object,
 620  *          \c GL_FALSE otherwise.
 621  */
 622 GLboolean GLAPIENTRY
 623 _mesa_IsVertexArray( GLuint id )
 624 {
 625    struct gl_vertex_array_object * obj;
 626    GET_CURRENT_CONTEXT(ctx);
 627    ASSERT_OUTSIDE_BEGIN_END_WITH_RETVAL(ctx, GL_FALSE);
 628
 629    if (id == 0)
 630       return GL_FALSE;
 631
 632    obj = _mesa_lookup_vao(ctx, id);
 633    if (obj == NULL)
 634       return GL_FALSE;
 635
 636    return obj->EverBound;
 637 }
 638
 639
 640 /**
 641  * Sets the element array buffer binding of a vertex array object.
 642  *
 643  * This is the ARB_direct_state_access equivalent of
 644  * glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, buffer).
 645  */
 646 void GLAPIENTRY
 647 _mesa_VertexArrayElementBuffer(GLuint vaobj, GLuint buffer)
 648 {
 649    GET_CURRENT_CONTEXT(ctx);
 650    struct gl_vertex_array_object *vao;
 651    struct gl_buffer_object *bufObj;
 652
 653    ASSERT_OUTSIDE_BEGIN_END(ctx);
 654
 655    /* The GL_ARB_direct_state_access specification says:
 656     *
 657     *    "An INVALID_OPERATION error is generated by VertexArrayElementBuffer
 658     *     if <vaobj> is not [compatibility profile: zero or] the name of an
 659     *     existing vertex array object."
 660     */
 661    vao =_mesa_lookup_vao_err(ctx, vaobj, "glVertexArrayElementBuffer");
 662    if (!vao)
 663       return;
 664
 665    /* The GL_ARB_direct_state_access specification says:
 666     *
 667     *    "An INVALID_OPERATION error is generated if <buffer> is not zero or
 668     *     the name of an existing buffer object."
 669     */
 670    if (buffer != 0)
 671       bufObj = _mesa_lookup_bufferobj_err(ctx, buffer,
 672                                           "glVertexArrayElementBuffer");
 673    else
 674       bufObj = ctx->Shared->NullBufferObj;
 675
 676    if (bufObj)
 677       _mesa_reference_buffer_object(ctx, &vao->IndexBufferObj, bufObj);
 678 }
 679
 680
 681 void GLAPIENTRY
 682 _mesa_GetVertexArrayiv(GLuint vaobj, GLenum pname, GLint *param)
 683 {
 684    GET_CURRENT_CONTEXT(ctx);
 685    struct gl_vertex_array_object *vao;
 686
 687    ASSERT_OUTSIDE_BEGIN_END(ctx);
 688
 689    /* The GL_ARB_direct_state_access specification says:
 690     *
 691     *   "An INVALID_OPERATION error is generated if <vaobj> is not
 692     *    [compatibility profile: zero or] the name of an existing
 693     *    vertex array object."
 694     */
 695    vao =_mesa_lookup_vao_err(ctx, vaobj, "glGetVertexArrayiv");
 696    if (!vao)
 697       return;
 698
 699    /* The GL_ARB_direct_state_access specification says:
 700     *
 701     *   "An INVALID_ENUM error is generated if <pname> is not
 702     *    ELEMENT_ARRAY_BUFFER_BINDING."
 703     */
 704    if (pname != GL_ELEMENT_ARRAY_BUFFER_BINDING) {
 705       _mesa_error(ctx, GL_INVALID_ENUM,
 706                   "glGetVertexArrayiv(pname != "
 707                   "GL_ELEMENT_ARRAY_BUFFER_BINDING)");
 708       return;
 709    }
 710
 711    param[0] = vao->IndexBufferObj->Name;
 712 }