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          _mesa_delete_vao(ctx, oldObj);
 207
 208       *ptr = NULL;
 209    }
 210    assert(!*ptr);
 211
 212    if (vao) {
 213       /* reference new array object */
 214       mtx_lock(&vao->Mutex);
 215       if (vao->RefCount == 0) {
 216          /* this array's being deleted (look just above) */
 217          /* Not sure this can every really happen.  Warn if it does. */
 218          _mesa_problem(NULL, "referencing deleted array object");
 219          *ptr = NULL;
 220       }
 221       else {
 222          vao->RefCount++;
 223          *ptr = vao;
 224       }
 225       mtx_unlock(&vao->Mutex);
 226    }
 227 }
 228
 229
 230
 231 static void
 232 init_array(struct gl_context *ctx,
 233            struct gl_vertex_array_object *obj, GLuint index, GLint size, GLint type)
 234 {
 235    struct gl_vertex_attrib_array *array = &obj->VertexAttrib[index];
 236    struct gl_vertex_buffer_binding *binding = &obj->VertexBinding[index];
 237
 238    array->Size = size;
 239    array->Type = type;
 240    array->Format = GL_RGBA; /* only significant for GL_EXT_vertex_array_bgra */
 241    array->Stride = 0;
 242    array->Ptr = NULL;
 243    array->RelativeOffset = 0;
 244    array->Enabled = GL_FALSE;
 245    array->Normalized = GL_FALSE;
 246    array->Integer = GL_FALSE;
 247    array->Doubles = GL_FALSE;
 248    array->_ElementSize = size * _mesa_sizeof_type(type);
 249    array->VertexBinding = index;
 250
 251    binding->Offset = 0;
 252    binding->Stride = array->_ElementSize;
 253    binding->BufferObj = NULL;
 254    binding->_BoundArrays = BITFIELD64_BIT(index);
 255
 256    /* Vertex array buffers */
 257    _mesa_reference_buffer_object(ctx, &binding->BufferObj,
 258                                  ctx->Shared->NullBufferObj);
 259 }
 260
 261
 262 /**
 263  * Initialize a gl_vertex_array_object's arrays.
 264  */
 265 void
 266 _mesa_initialize_vao(struct gl_context *ctx,
 267                      struct gl_vertex_array_object *obj,
 268                      GLuint name)
 269 {
 270    GLuint i;
 271
 272    obj->Name = name;
 273
 274    mtx_init(&obj->Mutex, mtx_plain);
 275    obj->RefCount = 1;
 276
 277    /* Init the individual arrays */
 278    for (i = 0; i < ARRAY_SIZE(obj->VertexAttrib); i++) {
 279       switch (i) {
 280       case VERT_ATTRIB_WEIGHT:
 281          init_array(ctx, obj, VERT_ATTRIB_WEIGHT, 1, GL_FLOAT);
 282          break;
 283       case VERT_ATTRIB_NORMAL:
 284          init_array(ctx, obj, VERT_ATTRIB_NORMAL, 3, GL_FLOAT);
 285          break;
 286       case VERT_ATTRIB_COLOR1:
 287          init_array(ctx, obj, VERT_ATTRIB_COLOR1, 3, GL_FLOAT);
 288          break;
 289       case VERT_ATTRIB_FOG:
 290          init_array(ctx, obj, VERT_ATTRIB_FOG, 1, GL_FLOAT);
 291          break;
 292       case VERT_ATTRIB_COLOR_INDEX:
 293          init_array(ctx, obj, VERT_ATTRIB_COLOR_INDEX, 1, GL_FLOAT);
 294          break;
 295       case VERT_ATTRIB_EDGEFLAG:
 296          init_array(ctx, obj, VERT_ATTRIB_EDGEFLAG, 1, GL_BOOL);
 297          break;
 298       case VERT_ATTRIB_POINT_SIZE:
 299          init_array(ctx, obj, VERT_ATTRIB_POINT_SIZE, 1, GL_FLOAT);
 300          break;
 301       default:
 302          init_array(ctx, obj, i, 4, GL_FLOAT);
 303          break;
 304       }
 305    }
 306
 307    _mesa_reference_buffer_object(ctx, &obj->IndexBufferObj,
 308                                  ctx->Shared->NullBufferObj);
 309 }
 310
 311
 312 /**
 313  * Add the given array object to the array object pool.
 314  */
 315 static void
 316 save_array_object( struct gl_context *ctx, struct gl_vertex_array_object *obj )
 317 {
 318    if (obj->Name > 0) {
 319       /* insert into hash table */
 320       _mesa_HashInsert(ctx->Array.Objects, obj->Name, obj);
 321    }
 322 }
 323
 324
 325 /**
 326  * Remove the given array object from the array object pool.
 327  * Do not deallocate the array object though.
 328  */
 329 static void
 330 remove_array_object( struct gl_context *ctx, struct gl_vertex_array_object *obj )
 331 {
 332    if (obj->Name > 0) {
 333       /* remove from hash table */
 334       _mesa_HashRemove(ctx->Array.Objects, obj->Name);
 335    }
 336 }
 337
 338
 339 /**
 340  * Updates the derived gl_client_arrays when a gl_vertex_attrib_array
 341  * or a gl_vertex_buffer_binding has changed.
 342  */
 343 void
 344 _mesa_update_vao_client_arrays(struct gl_context *ctx,
 345                                struct gl_vertex_array_object *vao)
 346 {
 347    GLbitfield64 arrays = vao->NewArrays;
 348
 349    while (arrays) {
 350       struct gl_client_array *client_array;
 351       struct gl_vertex_attrib_array *attrib_array;
 352       struct gl_vertex_buffer_binding *buffer_binding;
 353
 354       GLint attrib = ffsll(arrays) - 1;
 355       arrays ^= BITFIELD64_BIT(attrib);
 356
 357       attrib_array = &vao->VertexAttrib[attrib];
 358       buffer_binding = &vao->VertexBinding[attrib_array->VertexBinding];
 359       client_array = &vao->_VertexAttrib[attrib];
 360
 361       _mesa_update_client_array(ctx, client_array, attrib_array,
 362                                 buffer_binding);
 363    }
 364 }
 365
 366
 367 /**********************************************************************/
 368 /* API Functions                                                      */
 369 /**********************************************************************/
 370
 371
 372 /**
 373  * Helper for _mesa_BindVertexArray() and _mesa_BindVertexArrayAPPLE().
 374  * \param genRequired  specifies behavour when id was not generated with
 375  *                     glGenVertexArrays().
 376  */
 377 static void
 378 bind_vertex_array(struct gl_context *ctx, GLuint id, GLboolean genRequired)
 379 {
 380    struct gl_vertex_array_object * const oldObj = ctx->Array.VAO;
 381    struct gl_vertex_array_object *newObj = NULL;
 382
 383    assert(oldObj != NULL);
 384
 385    if ( oldObj->Name == id )
 386       return;   /* rebinding the same array object- no change */
 387
 388    /*
 389     * Get pointer to new array object (newObj)
 390     */
 391    if (id == 0) {
 392       /* The spec says there is no array object named 0, but we use
 393        * one internally because it simplifies things.
 394        */
 395       newObj = ctx->Array.DefaultVAO;
 396    }
 397    else {
 398       /* non-default array object */
 399       newObj = _mesa_lookup_vao(ctx, id);
 400       if (!newObj) {
 401          if (genRequired) {
 402             _mesa_error(ctx, GL_INVALID_OPERATION,
 403                         "glBindVertexArray(non-gen name)");
 404             return;
 405          }
 406
 407          /* For APPLE version, generate a new array object now */
 408          newObj = _mesa_new_vao(ctx, id);
 409          if (!newObj) {
 410             _mesa_error(ctx, GL_OUT_OF_MEMORY, "glBindVertexArrayAPPLE");
 411             return;
 412          }
 413
 414          save_array_object(ctx, newObj);
 415       }
 416
 417       if (!newObj->EverBound) {
 418          /* The "Interactions with APPLE_vertex_array_object" section of the
 419           * GL_ARB_vertex_array_object spec says:
 420           *
 421           *     "The first bind call, either BindVertexArray or
 422           *     BindVertexArrayAPPLE, determines the semantic of the object."
 423           */
 424          newObj->ARBsemantics = genRequired;
 425          newObj->EverBound = GL_TRUE;
 426       }
 427    }
 428
 429    if (ctx->Array.DrawMethod == DRAW_ARRAYS) {
 430       /* The _DrawArrays pointer is pointing at the VAO being unbound and
 431        * that VAO may be in the process of being deleted. If it's not going
 432        * to be deleted, this will have no effect, because the pointer needs
 433        * to be updated by the VBO module anyway.
 434        *
 435        * Before the VBO module can update the pointer, we have to set it
 436        * to NULL for drivers not to set up arrays which are not bound,
 437        * or to prevent a crash if the VAO being unbound is going to be
 438        * deleted.
 439        */
 440       ctx->Array._DrawArrays = NULL;
 441       ctx->Array.DrawMethod = DRAW_NONE;
 442    }
 443
 444    ctx->NewState |= _NEW_ARRAY;
 445    _mesa_reference_vao(ctx, &ctx->Array.VAO, newObj);
 446
 447    /* Pass BindVertexArray call to device driver */
 448    if (ctx->Driver.BindArrayObject && newObj)
 449       ctx->Driver.BindArrayObject(ctx, newObj);
 450 }
 451
 452
 453 /**
 454  * ARB version of glBindVertexArray()
 455  * This function behaves differently from glBindVertexArrayAPPLE() in
 456  * that this function requires all ids to have been previously generated
 457  * by glGenVertexArrays[APPLE]().
 458  */
 459 void GLAPIENTRY
 460 _mesa_BindVertexArray( GLuint id )
 461 {
 462    GET_CURRENT_CONTEXT(ctx);
 463    bind_vertex_array(ctx, id, GL_TRUE);
 464 }
 465
 466
 467 /**
 468  * Bind a new array.
 469  *
 470  * \todo
 471  * The binding could be done more efficiently by comparing the non-NULL
 472  * pointers in the old and new objects.  The only arrays that are "dirty" are
 473  * the ones that are non-NULL in either object.
 474  */
 475 void GLAPIENTRY
 476 _mesa_BindVertexArrayAPPLE( GLuint id )
 477 {
 478    GET_CURRENT_CONTEXT(ctx);
 479    bind_vertex_array(ctx, id, GL_FALSE);
 480 }
 481
 482
 483 /**
 484  * Delete a set of array objects.
 485  *
 486  * \param n      Number of array objects to delete.
 487  * \param ids    Array of \c n array object IDs.
 488  */
 489 void GLAPIENTRY
 490 _mesa_DeleteVertexArrays(GLsizei n, const GLuint *ids)
 491 {
 492    GET_CURRENT_CONTEXT(ctx);
 493    GLsizei i;
 494
 495    if (n < 0) {
 496       _mesa_error(ctx, GL_INVALID_VALUE, "glDeleteVertexArray(n)");
 497       return;
 498    }
 499
 500    for (i = 0; i < n; i++) {
 501       struct gl_vertex_array_object *obj = _mesa_lookup_vao(ctx, ids[i]);
 502
 503       if ( obj != NULL ) {
 504          assert( obj->Name == ids[i] );
 505
 506          /* If the array object is currently bound, the spec says "the binding
 507           * for that object reverts to zero and the default vertex array
 508           * becomes current."
 509           */
 510          if ( obj == ctx->Array.VAO ) {
 511             _mesa_BindVertexArray(0);
 512          }
 513
 514          /* The ID is immediately freed for re-use */
 515          remove_array_object(ctx, obj);
 516
 517          if (ctx->Array.LastLookedUpVAO == obj)
 518             _mesa_reference_vao(ctx, &ctx->Array.LastLookedUpVAO, NULL);
 519
 520          /* Unreference the array object.
 521           * If refcount hits zero, the object will be deleted.
 522           */
 523          _mesa_reference_vao(ctx, &obj, NULL);
 524       }
 525    }
 526 }
 527
 528
 529 /**
 530  * Generate a set of unique array object IDs and store them in \c arrays.
 531  * Helper for _mesa_GenVertexArrays[APPLE]() and _mesa_CreateVertexArrays()
 532  * below.
 533  *
 534  * \param n       Number of IDs to generate.
 535  * \param arrays  Array of \c n locations to store the IDs.
 536  * \param create  Indicates that the objects should also be created.
 537  * \param func    The name of the GL entry point.
 538  */
 539 static void
 540 gen_vertex_arrays(struct gl_context *ctx, GLsizei n, GLuint *arrays,
 541                   bool create, const char *func)
 542 {
 543    GLuint first;
 544    GLint i;
 545
 546    if (n < 0) {
 547       _mesa_error(ctx, GL_INVALID_VALUE, "%s(n < 0)", func);
 548       return;
 549    }
 550
 551    if (!arrays) {
 552       return;
 553    }
 554
 555    first = _mesa_HashFindFreeKeyBlock(ctx->Array.Objects, n);
 556
 557    /* For the sake of simplicity we create the array objects in both
 558     * the Gen* and Create* cases.  The only difference is the value of
 559     * EverBound, which is set to true in the Create* case.
 560     */
 561    for (i = 0; i < n; i++) {
 562       struct gl_vertex_array_object *obj;
 563       GLuint name = first + i;
 564
 565       obj = _mesa_new_vao(ctx, name);
 566       if (!obj) {
 567          _mesa_error(ctx, GL_OUT_OF_MEMORY, "%s", func);
 568          return;
 569       }
 570       obj->EverBound = create;
 571       save_array_object(ctx, obj);
 572       arrays[i] = first + i;
 573    }
 574 }
 575
 576
 577 /**
 578  * ARB version of glGenVertexArrays()
 579  * All arrays will be required to live in VBOs.
 580  */
 581 void GLAPIENTRY
 582 _mesa_GenVertexArrays(GLsizei n, GLuint *arrays)
 583 {
 584    GET_CURRENT_CONTEXT(ctx);
 585    gen_vertex_arrays(ctx, n, arrays, false, "glGenVertexArrays");
 586 }
 587
 588
 589 /**
 590  * APPLE version of glGenVertexArraysAPPLE()
 591  * Arrays may live in VBOs or ordinary memory.
 592  */
 593 void GLAPIENTRY
 594 _mesa_GenVertexArraysAPPLE(GLsizei n, GLuint *arrays)
 595 {
 596    GET_CURRENT_CONTEXT(ctx);
 597    gen_vertex_arrays(ctx, n, arrays, false, "glGenVertexArraysAPPLE");
 598 }
 599
 600
 601 /**
 602  * ARB_direct_state_access
 603  * Generates ID's and creates the array objects.
 604  */
 605 void GLAPIENTRY
 606 _mesa_CreateVertexArrays(GLsizei n, GLuint *arrays)
 607 {
 608    GET_CURRENT_CONTEXT(ctx);
 609    gen_vertex_arrays(ctx, n, arrays, true, "glCreateVertexArrays");
 610 }
 611
 612
 613 /**
 614  * Determine if ID is the name of an array object.
 615  *
 616  * \param id  ID of the potential array object.
 617  * \return  \c GL_TRUE if \c id is the name of a array object,
 618  *          \c GL_FALSE otherwise.
 619  */
 620 GLboolean GLAPIENTRY
 621 _mesa_IsVertexArray( GLuint id )
 622 {
 623    struct gl_vertex_array_object * obj;
 624    GET_CURRENT_CONTEXT(ctx);
 625    ASSERT_OUTSIDE_BEGIN_END_WITH_RETVAL(ctx, GL_FALSE);
 626
 627    if (id == 0)
 628       return GL_FALSE;
 629
 630    obj = _mesa_lookup_vao(ctx, id);
 631    if (obj == NULL)
 632       return GL_FALSE;
 633
 634    return obj->EverBound;
 635 }
 636
 637
 638 /**
 639  * Sets the element array buffer binding of a vertex array object.
 640  *
 641  * This is the ARB_direct_state_access equivalent of
 642  * glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, buffer).
 643  */
 644 void GLAPIENTRY
 645 _mesa_VertexArrayElementBuffer(GLuint vaobj, GLuint buffer)
 646 {
 647    GET_CURRENT_CONTEXT(ctx);
 648    struct gl_vertex_array_object *vao;
 649    struct gl_buffer_object *bufObj;
 650
 651    ASSERT_OUTSIDE_BEGIN_END(ctx);
 652
 653    /* The GL_ARB_direct_state_access specification says:
 654     *
 655     *    "An INVALID_OPERATION error is generated by VertexArrayElementBuffer
 656     *     if <vaobj> is not [compatibility profile: zero or] the name of an
 657     *     existing vertex array object."
 658     */
 659    vao =_mesa_lookup_vao_err(ctx, vaobj, "glVertexArrayElementBuffer");
 660    if (!vao)
 661       return;
 662
 663    /* The GL_ARB_direct_state_access specification says:
 664     *
 665     *    "An INVALID_OPERATION error is generated if <buffer> is not zero or
 666     *     the name of an existing buffer object."
 667     */
 668    if (buffer != 0)
 669       bufObj = _mesa_lookup_bufferobj_err(ctx, buffer,
 670                                           "glVertexArrayElementBuffer");
 671    else
 672       bufObj = ctx->Shared->NullBufferObj;
 673
 674    if (bufObj)
 675       _mesa_reference_buffer_object(ctx, &vao->IndexBufferObj, bufObj);
 676 }
 677
 678
 679 void GLAPIENTRY
 680 _mesa_GetVertexArrayiv(GLuint vaobj, GLenum pname, GLint *param)
 681 {
 682    GET_CURRENT_CONTEXT(ctx);
 683    struct gl_vertex_array_object *vao;
 684
 685    ASSERT_OUTSIDE_BEGIN_END(ctx);
 686
 687    /* The GL_ARB_direct_state_access specification says:
 688     *
 689     *   "An INVALID_OPERATION error is generated if <vaobj> is not
 690     *    [compatibility profile: zero or] the name of an existing
 691     *    vertex array object."
 692     */
 693    vao =_mesa_lookup_vao_err(ctx, vaobj, "glGetVertexArrayiv");
 694    if (!vao)
 695       return;
 696
 697    /* The GL_ARB_direct_state_access specification says:
 698     *
 699     *   "An INVALID_ENUM error is generated if <pname> is not
 700     *    ELEMENT_ARRAY_BUFFER_BINDING."
 701     */
 702    if (pname != GL_ELEMENT_ARRAY_BUFFER_BINDING) {
 703       _mesa_error(ctx, GL_INVALID_ENUM,
 704                   "glGetVertexArrayiv(pname != "
 705                   "GL_ELEMENT_ARRAY_BUFFER_BINDING)");
 706       return;
 707    }
 708
 709    param[0] = vao->IndexBufferObj->Name;
 710 }