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 #include "util/bitscan.h"
  56
  57
  58 /**
  59  * Look up the array object for the given ID.
  60  *
  61  * \returns
  62  * Either a pointer to the array object with the specified ID or \c NULL for
  63  * a non-existent ID.  The spec defines ID 0 as being technically
  64  * non-existent.
  65  */
  66
  67 struct gl_vertex_array_object *
  68 _mesa_lookup_vao(struct gl_context *ctx, GLuint id)
  69 {
  70    if (id == 0)
  71       return NULL;
  72    else
  73       return (struct gl_vertex_array_object *)
  74          _mesa_HashLookup(ctx->Array.Objects, id);
  75 }
  76
  77
  78 /**
  79  * Looks up the array object for the given ID.
  80  *
  81  * Unlike _mesa_lookup_vao, this function generates a GL_INVALID_OPERATION
  82  * error if the array object does not exist. It also returns the default
  83  * array object when ctx is a compatibility profile context and id is zero.
  84  */
  85 struct gl_vertex_array_object *
  86 _mesa_lookup_vao_err(struct gl_context *ctx, GLuint id, const char *caller)
  87 {
  88    /* The ARB_direct_state_access specification says:
  89     *
  90     *    "<vaobj> is [compatibility profile:
  91     *     zero, indicating the default vertex array object, or]
  92     *     the name of the vertex array object."
  93     */
  94    if (id == 0) {
  95       if (ctx->API == API_OPENGL_CORE) {
  96          _mesa_error(ctx, GL_INVALID_OPERATION,
  97                      "%s(zero is not valid vaobj name in a core profile "
  98                      "context)", caller);
  99          return NULL;
 100       }
 101
 102       return ctx->Array.DefaultVAO;
 103    } else {
 104       struct gl_vertex_array_object *vao;
 105
 106       if (ctx->Array.LastLookedUpVAO &&
 107           ctx->Array.LastLookedUpVAO->Name == id) {
 108          vao = ctx->Array.LastLookedUpVAO;
 109       } else {
 110          vao = (struct gl_vertex_array_object *)
 111             _mesa_HashLookup(ctx->Array.Objects, id);
 112
 113          /* The ARB_direct_state_access specification says:
 114           *
 115           *    "An INVALID_OPERATION error is generated if <vaobj> is not
 116           *     [compatibility profile: zero or] the name of an existing
 117           *     vertex array object."
 118           */
 119          if (!vao || !vao->EverBound) {
 120             _mesa_error(ctx, GL_INVALID_OPERATION,
 121                         "%s(non-existent vaobj=%u)", caller, id);
 122             return NULL;
 123          }
 124
 125          _mesa_reference_vao(ctx, &ctx->Array.LastLookedUpVAO, vao);
 126       }
 127
 128       return vao;
 129    }
 130 }
 131
 132
 133 /**
 134  * For all the vertex binding points in the array object, unbind any pointers
 135  * to any buffer objects (VBOs).
 136  * This is done just prior to array object destruction.
 137  */
 138 static void
 139 unbind_array_object_vbos(struct gl_context *ctx, struct gl_vertex_array_object *obj)
 140 {
 141    GLuint i;
 142
 143    for (i = 0; i < ARRAY_SIZE(obj->BufferBinding); i++)
 144       _mesa_reference_buffer_object(ctx, &obj->BufferBinding[i].BufferObj, NULL);
 145
 146    for (i = 0; i < ARRAY_SIZE(obj->_VertexAttrib); i++)
 147       _mesa_reference_buffer_object(ctx, &obj->_VertexAttrib[i].BufferObj, NULL);
 148 }
 149
 150
 151 /**
 152  * Allocate and initialize a new vertex array object.
 153  */
 154 struct gl_vertex_array_object *
 155 _mesa_new_vao(struct gl_context *ctx, GLuint name)
 156 {
 157    struct gl_vertex_array_object *obj = CALLOC_STRUCT(gl_vertex_array_object);
 158    if (obj)
 159       _mesa_initialize_vao(ctx, obj, name);
 160    return obj;
 161 }
 162
 163
 164 /**
 165  * Delete an array object.
 166  */
 167 void
 168 _mesa_delete_vao(struct gl_context *ctx, struct gl_vertex_array_object *obj)
 169 {
 170    unbind_array_object_vbos(ctx, obj);
 171    _mesa_reference_buffer_object(ctx, &obj->IndexBufferObj, NULL);
 172    free(obj->Label);
 173    free(obj);
 174 }
 175
 176
 177 /**
 178  * Set ptr to vao w/ reference counting.
 179  * Note: this should only be called from the _mesa_reference_vao()
 180  * inline function.
 181  */
 182 void
 183 _mesa_reference_vao_(struct gl_context *ctx,
 184                      struct gl_vertex_array_object **ptr,
 185                      struct gl_vertex_array_object *vao)
 186 {
 187    assert(*ptr != vao);
 188
 189    if (*ptr) {
 190       /* Unreference the old array object */
 191       struct gl_vertex_array_object *oldObj = *ptr;
 192
 193       assert(oldObj->RefCount > 0);
 194       oldObj->RefCount--;
 195
 196       if (oldObj->RefCount == 0)
 197          _mesa_delete_vao(ctx, oldObj);
 198
 199       *ptr = NULL;
 200    }
 201    assert(!*ptr);
 202
 203    if (vao) {
 204       /* reference new array object */
 205       assert(vao->RefCount > 0);
 206
 207       vao->RefCount++;
 208       *ptr = vao;
 209    }
 210 }
 211
 212
 213 /**
 214  * Initialize attribtes of a vertex array within a vertex array object.
 215  * \param vao  the container vertex array object
 216  * \param index  which array in the VAO to initialize
 217  * \param size  number of components (1, 2, 3 or 4) per attribute
 218  * \param type  datatype of the attribute (GL_FLOAT, GL_INT, etc).
 219  */
 220 static void
 221 init_array(struct gl_context *ctx,
 222            struct gl_vertex_array_object *vao,
 223            GLuint index, GLint size, GLint type)
 224 {
 225    struct gl_array_attributes *array = &vao->VertexAttrib[index];
 226    struct gl_vertex_buffer_binding *binding = &vao->BufferBinding[index];
 227
 228    array->Size = size;
 229    array->Type = type;
 230    array->Format = GL_RGBA; /* only significant for GL_EXT_vertex_array_bgra */
 231    array->Stride = 0;
 232    array->Ptr = NULL;
 233    array->RelativeOffset = 0;
 234    array->Enabled = GL_FALSE;
 235    array->Normalized = GL_FALSE;
 236    array->Integer = GL_FALSE;
 237    array->Doubles = GL_FALSE;
 238    array->_ElementSize = size * _mesa_sizeof_type(type);
 239    array->BufferBindingIndex = index;
 240
 241    binding->Offset = 0;
 242    binding->Stride = array->_ElementSize;
 243    binding->BufferObj = NULL;
 244    binding->_BoundArrays = BITFIELD64_BIT(index);
 245
 246    /* Vertex array buffers */
 247    _mesa_reference_buffer_object(ctx, &binding->BufferObj,
 248                                  ctx->Shared->NullBufferObj);
 249 }
 250
 251
 252 /**
 253  * Initialize a gl_vertex_array_object's arrays.
 254  */
 255 void
 256 _mesa_initialize_vao(struct gl_context *ctx,
 257                      struct gl_vertex_array_object *vao,
 258                      GLuint name)
 259 {
 260    GLuint i;
 261
 262    vao->Name = name;
 263
 264    vao->RefCount = 1;
 265
 266    /* Init the individual arrays */
 267    for (i = 0; i < ARRAY_SIZE(vao->VertexAttrib); i++) {
 268       switch (i) {
 269       case VERT_ATTRIB_WEIGHT:
 270          init_array(ctx, vao, VERT_ATTRIB_WEIGHT, 1, GL_FLOAT);
 271          break;
 272       case VERT_ATTRIB_NORMAL:
 273          init_array(ctx, vao, VERT_ATTRIB_NORMAL, 3, GL_FLOAT);
 274          break;
 275       case VERT_ATTRIB_COLOR1:
 276          init_array(ctx, vao, VERT_ATTRIB_COLOR1, 3, GL_FLOAT);
 277          break;
 278       case VERT_ATTRIB_FOG:
 279          init_array(ctx, vao, VERT_ATTRIB_FOG, 1, GL_FLOAT);
 280          break;
 281       case VERT_ATTRIB_COLOR_INDEX:
 282          init_array(ctx, vao, VERT_ATTRIB_COLOR_INDEX, 1, GL_FLOAT);
 283          break;
 284       case VERT_ATTRIB_EDGEFLAG:
 285          init_array(ctx, vao, VERT_ATTRIB_EDGEFLAG, 1, GL_BOOL);
 286          break;
 287       case VERT_ATTRIB_POINT_SIZE:
 288          init_array(ctx, vao, VERT_ATTRIB_POINT_SIZE, 1, GL_FLOAT);
 289          break;
 290       default:
 291          init_array(ctx, vao, i, 4, GL_FLOAT);
 292          break;
 293       }
 294    }
 295
 296    _mesa_reference_buffer_object(ctx, &vao->IndexBufferObj,
 297                                  ctx->Shared->NullBufferObj);
 298 }
 299
 300
 301 /**
 302  * Add the given array object to the array object pool.
 303  */
 304 static void
 305 save_array_object(struct gl_context *ctx, struct gl_vertex_array_object *vao)
 306 {
 307    if (vao->Name > 0) {
 308       /* insert into hash table */
 309       _mesa_HashInsert(ctx->Array.Objects, vao->Name, vao);
 310    }
 311 }
 312
 313
 314 /**
 315  * Remove the given array object from the array object pool.
 316  * Do not deallocate the array object though.
 317  */
 318 static void
 319 remove_array_object(struct gl_context *ctx, struct gl_vertex_array_object *vao)
 320 {
 321    if (vao->Name > 0) {
 322       /* remove from hash table */
 323       _mesa_HashRemove(ctx->Array.Objects, vao->Name);
 324    }
 325 }
 326
 327
 328 /**
 329  * Updates the derived gl_vertex_arrays when a gl_vertex_attrib_array
 330  * or a gl_vertex_buffer_binding has changed.
 331  */
 332 void
 333 _mesa_update_vao_client_arrays(struct gl_context *ctx,
 334                                struct gl_vertex_array_object *vao)
 335 {
 336    GLbitfield64 arrays = vao->NewArrays;
 337
 338    while (arrays) {
 339       const int attrib = u_bit_scan64(&arrays);
 340       struct gl_vertex_array *client_array = &vao->_VertexAttrib[attrib];
 341       const struct gl_array_attributes *attrib_array =
 342          &vao->VertexAttrib[attrib];
 343       const struct gl_vertex_buffer_binding *buffer_binding =
 344          &vao->BufferBinding[attrib_array->BufferBindingIndex];
 345
 346       _mesa_update_client_array(ctx, client_array, attrib_array,
 347                                 buffer_binding);
 348    }
 349 }
 350
 351
 352 bool
 353 _mesa_all_varyings_in_vbos(const struct gl_vertex_array_object *vao)
 354 {
 355    /* Walk those enabled arrays that have the default vbo attached */
 356    GLbitfield64 mask = vao->_Enabled & ~vao->VertexAttribBufferMask;
 357
 358    while (mask) {
 359       /* Do not use u_bit_scan64 as we can walk multiple
 360        * attrib arrays at once
 361        */
 362       const int i = ffsll(mask) - 1;
 363       const struct gl_array_attributes *attrib_array =
 364          &vao->VertexAttrib[i];
 365       const struct gl_vertex_buffer_binding *buffer_binding =
 366          &vao->BufferBinding[attrib_array->BufferBindingIndex];
 367
 368       /* Only enabled arrays shall appear in the _Enabled bitmask */
 369       assert(attrib_array->Enabled);
 370       /* We have already masked out vao->VertexAttribBufferMask  */
 371       assert(!_mesa_is_bufferobj(buffer_binding->BufferObj));
 372
 373       /* Bail out once we find the first non vbo with a non zero stride */
 374       if (buffer_binding->Stride != 0)
 375          return false;
 376
 377       /* Note that we cannot use the xor variant since the _BoundArray mask
 378        * may contain array attributes that are bound but not enabled.
 379        */
 380       mask &= ~buffer_binding->_BoundArrays;
 381    }
 382
 383    return true;
 384 }
 385
 386 bool
 387 _mesa_all_buffers_are_unmapped(const struct gl_vertex_array_object *vao)
 388 {
 389    /* Walk the enabled arrays that have a vbo attached */
 390    GLbitfield64 mask = vao->_Enabled & vao->VertexAttribBufferMask;
 391
 392    while (mask) {
 393       const int i = ffsll(mask) - 1;
 394       const struct gl_array_attributes *attrib_array =
 395          &vao->VertexAttrib[i];
 396       const struct gl_vertex_buffer_binding *buffer_binding =
 397          &vao->BufferBinding[attrib_array->BufferBindingIndex];
 398
 399       /* Only enabled arrays shall appear in the _Enabled bitmask */
 400       assert(attrib_array->Enabled);
 401       /* We have already masked with vao->VertexAttribBufferMask  */
 402       assert(_mesa_is_bufferobj(buffer_binding->BufferObj));
 403
 404       /* Bail out once we find the first disallowed mapping */
 405       if (_mesa_check_disallowed_mapping(buffer_binding->BufferObj))
 406          return false;
 407
 408       /* We have handled everything that is bound to this buffer_binding. */
 409       mask &= ~buffer_binding->_BoundArrays;
 410    }
 411
 412    return true;
 413 }
 414
 415 /**********************************************************************/
 416 /* API Functions                                                      */
 417 /**********************************************************************/
 418
 419
 420 /**
 421  * Helper for _mesa_BindVertexArray() and _mesa_BindVertexArrayAPPLE().
 422  * \param genRequired  specifies behavour when id was not generated with
 423  *                     glGenVertexArrays().
 424  */
 425 static void
 426 bind_vertex_array(struct gl_context *ctx, GLuint id, GLboolean genRequired)
 427 {
 428    struct gl_vertex_array_object * const oldObj = ctx->Array.VAO;
 429    struct gl_vertex_array_object *newObj = NULL;
 430
 431    assert(oldObj != NULL);
 432
 433    if ( oldObj->Name == id )
 434       return;   /* rebinding the same array object- no change */
 435
 436    /*
 437     * Get pointer to new array object (newObj)
 438     */
 439    if (id == 0) {
 440       /* The spec says there is no array object named 0, but we use
 441        * one internally because it simplifies things.
 442        */
 443       newObj = ctx->Array.DefaultVAO;
 444    }
 445    else {
 446       /* non-default array object */
 447       newObj = _mesa_lookup_vao(ctx, id);
 448       if (!newObj) {
 449          if (genRequired) {
 450             _mesa_error(ctx, GL_INVALID_OPERATION,
 451                         "glBindVertexArray(non-gen name)");
 452             return;
 453          }
 454
 455          /* For APPLE version, generate a new array object now */
 456          newObj = _mesa_new_vao(ctx, id);
 457          if (!newObj) {
 458             _mesa_error(ctx, GL_OUT_OF_MEMORY, "glBindVertexArrayAPPLE");
 459             return;
 460          }
 461
 462          save_array_object(ctx, newObj);
 463       }
 464
 465       if (!newObj->EverBound) {
 466          /* The "Interactions with APPLE_vertex_array_object" section of the
 467           * GL_ARB_vertex_array_object spec says:
 468           *
 469           *     "The first bind call, either BindVertexArray or
 470           *     BindVertexArrayAPPLE, determines the semantic of the object."
 471           */
 472          newObj->ARBsemantics = genRequired;
 473          newObj->EverBound = GL_TRUE;
 474       }
 475    }
 476
 477    if (ctx->Array.DrawMethod == DRAW_ARRAYS) {
 478       /* The _DrawArrays pointer is pointing at the VAO being unbound and
 479        * that VAO may be in the process of being deleted. If it's not going
 480        * to be deleted, this will have no effect, because the pointer needs
 481        * to be updated by the VBO module anyway.
 482        *
 483        * Before the VBO module can update the pointer, we have to set it
 484        * to NULL for drivers not to set up arrays which are not bound,
 485        * or to prevent a crash if the VAO being unbound is going to be
 486        * deleted.
 487        */
 488       ctx->Array._DrawArrays = NULL;
 489       ctx->Array.DrawMethod = DRAW_NONE;
 490    }
 491
 492    ctx->NewState |= _NEW_ARRAY;
 493    _mesa_reference_vao(ctx, &ctx->Array.VAO, newObj);
 494 }
 495
 496
 497 /**
 498  * ARB version of glBindVertexArray()
 499  * This function behaves differently from glBindVertexArrayAPPLE() in
 500  * that this function requires all ids to have been previously generated
 501  * by glGenVertexArrays[APPLE]().
 502  */
 503 void GLAPIENTRY
 504 _mesa_BindVertexArray( GLuint id )
 505 {
 506    GET_CURRENT_CONTEXT(ctx);
 507    bind_vertex_array(ctx, id, GL_TRUE);
 508 }
 509
 510
 511 /**
 512  * Bind a new array.
 513  *
 514  * \todo
 515  * The binding could be done more efficiently by comparing the non-NULL
 516  * pointers in the old and new objects.  The only arrays that are "dirty" are
 517  * the ones that are non-NULL in either object.
 518  */
 519 void GLAPIENTRY
 520 _mesa_BindVertexArrayAPPLE( GLuint id )
 521 {
 522    GET_CURRENT_CONTEXT(ctx);
 523    bind_vertex_array(ctx, id, GL_FALSE);
 524 }
 525
 526
 527 /**
 528  * Delete a set of array objects.
 529  *
 530  * \param n      Number of array objects to delete.
 531  * \param ids    Array of \c n array object IDs.
 532  */
 533 void GLAPIENTRY
 534 _mesa_DeleteVertexArrays(GLsizei n, const GLuint *ids)
 535 {
 536    GET_CURRENT_CONTEXT(ctx);
 537    GLsizei i;
 538
 539    if (n < 0) {
 540       _mesa_error(ctx, GL_INVALID_VALUE, "glDeleteVertexArray(n)");
 541       return;
 542    }
 543
 544    for (i = 0; i < n; i++) {
 545       struct gl_vertex_array_object *obj = _mesa_lookup_vao(ctx, ids[i]);
 546
 547       if ( obj != NULL ) {
 548          assert( obj->Name == ids[i] );
 549
 550          /* If the array object is currently bound, the spec says "the binding
 551           * for that object reverts to zero and the default vertex array
 552           * becomes current."
 553           */
 554          if ( obj == ctx->Array.VAO ) {
 555             _mesa_BindVertexArray(0);
 556          }
 557
 558          /* The ID is immediately freed for re-use */
 559          remove_array_object(ctx, obj);
 560
 561          if (ctx->Array.LastLookedUpVAO == obj)
 562             _mesa_reference_vao(ctx, &ctx->Array.LastLookedUpVAO, NULL);
 563
 564          /* Unreference the array object.
 565           * If refcount hits zero, the object will be deleted.
 566           */
 567          _mesa_reference_vao(ctx, &obj, NULL);
 568       }
 569    }
 570 }
 571
 572
 573 /**
 574  * Generate a set of unique array object IDs and store them in \c arrays.
 575  * Helper for _mesa_GenVertexArrays[APPLE]() and _mesa_CreateVertexArrays()
 576  * below.
 577  *
 578  * \param n       Number of IDs to generate.
 579  * \param arrays  Array of \c n locations to store the IDs.
 580  * \param create  Indicates that the objects should also be created.
 581  * \param func    The name of the GL entry point.
 582  */
 583 static void
 584 gen_vertex_arrays(struct gl_context *ctx, GLsizei n, GLuint *arrays,
 585                   bool create, const char *func)
 586 {
 587    GLuint first;
 588    GLint i;
 589
 590    if (n < 0) {
 591       _mesa_error(ctx, GL_INVALID_VALUE, "%s(n < 0)", func);
 592       return;
 593    }
 594
 595    if (!arrays) {
 596       return;
 597    }
 598
 599    first = _mesa_HashFindFreeKeyBlock(ctx->Array.Objects, n);
 600
 601    /* For the sake of simplicity we create the array objects in both
 602     * the Gen* and Create* cases.  The only difference is the value of
 603     * EverBound, which is set to true in the Create* case.
 604     */
 605    for (i = 0; i < n; i++) {
 606       struct gl_vertex_array_object *obj;
 607       GLuint name = first + i;
 608
 609       obj = _mesa_new_vao(ctx, name);
 610       if (!obj) {
 611          _mesa_error(ctx, GL_OUT_OF_MEMORY, "%s", func);
 612          return;
 613       }
 614       obj->EverBound = create;
 615       save_array_object(ctx, obj);
 616       arrays[i] = first + i;
 617    }
 618 }
 619
 620
 621 /**
 622  * ARB version of glGenVertexArrays()
 623  * All arrays will be required to live in VBOs.
 624  */
 625 void GLAPIENTRY
 626 _mesa_GenVertexArrays(GLsizei n, GLuint *arrays)
 627 {
 628    GET_CURRENT_CONTEXT(ctx);
 629    gen_vertex_arrays(ctx, n, arrays, false, "glGenVertexArrays");
 630 }
 631
 632
 633 /**
 634  * APPLE version of glGenVertexArraysAPPLE()
 635  * Arrays may live in VBOs or ordinary memory.
 636  */
 637 void GLAPIENTRY
 638 _mesa_GenVertexArraysAPPLE(GLsizei n, GLuint *arrays)
 639 {
 640    GET_CURRENT_CONTEXT(ctx);
 641    gen_vertex_arrays(ctx, n, arrays, false, "glGenVertexArraysAPPLE");
 642 }
 643
 644
 645 /**
 646  * ARB_direct_state_access
 647  * Generates ID's and creates the array objects.
 648  */
 649 void GLAPIENTRY
 650 _mesa_CreateVertexArrays(GLsizei n, GLuint *arrays)
 651 {
 652    GET_CURRENT_CONTEXT(ctx);
 653    gen_vertex_arrays(ctx, n, arrays, true, "glCreateVertexArrays");
 654 }
 655
 656
 657 /**
 658  * Determine if ID is the name of an array object.
 659  *
 660  * \param id  ID of the potential array object.
 661  * \return  \c GL_TRUE if \c id is the name of a array object,
 662  *          \c GL_FALSE otherwise.
 663  */
 664 GLboolean GLAPIENTRY
 665 _mesa_IsVertexArray( GLuint id )
 666 {
 667    struct gl_vertex_array_object * obj;
 668    GET_CURRENT_CONTEXT(ctx);
 669    ASSERT_OUTSIDE_BEGIN_END_WITH_RETVAL(ctx, GL_FALSE);
 670
 671    if (id == 0)
 672       return GL_FALSE;
 673
 674    obj = _mesa_lookup_vao(ctx, id);
 675    if (obj == NULL)
 676       return GL_FALSE;
 677
 678    return obj->EverBound;
 679 }
 680
 681
 682 /**
 683  * Sets the element array buffer binding of a vertex array object.
 684  *
 685  * This is the ARB_direct_state_access equivalent of
 686  * glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, buffer).
 687  */
 688 void GLAPIENTRY
 689 _mesa_VertexArrayElementBuffer(GLuint vaobj, GLuint buffer)
 690 {
 691    GET_CURRENT_CONTEXT(ctx);
 692    struct gl_vertex_array_object *vao;
 693    struct gl_buffer_object *bufObj;
 694
 695    ASSERT_OUTSIDE_BEGIN_END(ctx);
 696
 697    /* The GL_ARB_direct_state_access specification says:
 698     *
 699     *    "An INVALID_OPERATION error is generated by VertexArrayElementBuffer
 700     *     if <vaobj> is not [compatibility profile: zero or] the name of an
 701     *     existing vertex array object."
 702     */
 703    vao =_mesa_lookup_vao_err(ctx, vaobj, "glVertexArrayElementBuffer");
 704    if (!vao)
 705       return;
 706
 707    /* The GL_ARB_direct_state_access specification says:
 708     *
 709     *    "An INVALID_OPERATION error is generated if <buffer> is not zero or
 710     *     the name of an existing buffer object."
 711     */
 712    if (buffer != 0)
 713       bufObj = _mesa_lookup_bufferobj_err(ctx, buffer,
 714                                           "glVertexArrayElementBuffer");
 715    else
 716       bufObj = ctx->Shared->NullBufferObj;
 717
 718    if (bufObj)
 719       _mesa_reference_buffer_object(ctx, &vao->IndexBufferObj, bufObj);
 720 }
 721
 722
 723 void GLAPIENTRY
 724 _mesa_GetVertexArrayiv(GLuint vaobj, GLenum pname, GLint *param)
 725 {
 726    GET_CURRENT_CONTEXT(ctx);
 727    struct gl_vertex_array_object *vao;
 728
 729    ASSERT_OUTSIDE_BEGIN_END(ctx);
 730
 731    /* The GL_ARB_direct_state_access specification says:
 732     *
 733     *   "An INVALID_OPERATION error is generated if <vaobj> is not
 734     *    [compatibility profile: zero or] the name of an existing
 735     *    vertex array object."
 736     */
 737    vao =_mesa_lookup_vao_err(ctx, vaobj, "glGetVertexArrayiv");
 738    if (!vao)
 739       return;
 740
 741    /* The GL_ARB_direct_state_access specification says:
 742     *
 743     *   "An INVALID_ENUM error is generated if <pname> is not
 744     *    ELEMENT_ARRAY_BUFFER_BINDING."
 745     */
 746    if (pname != GL_ELEMENT_ARRAY_BUFFER_BINDING) {
 747       _mesa_error(ctx, GL_INVALID_ENUM,
 748                   "glGetVertexArrayiv(pname != "
 749                   "GL_ELEMENT_ARRAY_BUFFER_BINDING)");
 750       return;
 751    }
 752
 753    param[0] = vao->IndexBufferObj->Name;
 754 }