src/mesa/main/transformfeedback.c

   1 /*
   2  * Mesa 3-D graphics library
   3  *
   4  * Copyright (C) 2010  VMware, Inc.  All Rights Reserved.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a
   7  * copy of this software and associated documentation files (the "Software"),
   8  * to deal in the Software without restriction, including without limitation
   9  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  10  * and/or sell copies of the Software, and to permit persons to whom the
  11  * Software is furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included
  14  * in all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  17  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  20  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  21  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  22  * OTHER DEALINGS IN THE SOFTWARE.
  23  */
  24
  25
  26 /*
  27  * Transform feedback support.
  28  *
  29  * Authors:
  30  *   Brian Paul
  31  */
  32
  33
  34 #include "buffers.h"
  35 #include "context.h"
  36 #include "hash.h"
  37 #include "macros.h"
  38 #include "mtypes.h"
  39 #include "transformfeedback.h"
  40 #include "shaderapi.h"
  41 #include "shaderobj.h"
  42 #include "main/dispatch.h"
  43
  44 #include "program/prog_parameter.h"
  45
  46 struct using_program_tuple
  47 {
  48    struct gl_shader_program *shProg;
  49    bool found;
  50 };
  51
  52 static void
  53 active_xfb_object_references_program(GLuint key, void *data, void *user_data)
  54 {
  55    struct using_program_tuple *callback_data = user_data;
  56    struct gl_transform_feedback_object *obj = data;
  57    if (obj->Active && obj->shader_program == callback_data->shProg)
  58       callback_data->found = true;
  59 }
  60
  61 /**
  62  * Return true if any active transform feedback object is using a program.
  63  */
  64 bool
  65 _mesa_transform_feedback_is_using_program(struct gl_context *ctx,
  66                                           struct gl_shader_program *shProg)
  67 {
  68    struct using_program_tuple callback_data;
  69    callback_data.shProg = shProg;
  70    callback_data.found = false;
  71
  72    _mesa_HashWalk(ctx->TransformFeedback.Objects,
  73                   active_xfb_object_references_program, &callback_data);
  74
  75    /* Also check DefaultObject, as it's not in the Objects hash table. */
  76    active_xfb_object_references_program(0, ctx->TransformFeedback.DefaultObject,
  77                                         &callback_data);
  78
  79    return callback_data.found;
  80 }
  81
  82 /**
  83  * Do reference counting of transform feedback buffers.
  84  */
  85 static void
  86 reference_transform_feedback_object(struct gl_transform_feedback_object **ptr,
  87                                     struct gl_transform_feedback_object *obj)
  88 {
  89    if (*ptr == obj)
  90       return;
  91
  92    if (*ptr) {
  93       /* Unreference the old object */
  94       struct gl_transform_feedback_object *oldObj = *ptr;
  95
  96       assert(oldObj->RefCount > 0);
  97       oldObj->RefCount--;
  98
  99       if (oldObj->RefCount == 0) {
 100          GET_CURRENT_CONTEXT(ctx);
 101          if (ctx)
 102             ctx->Driver.DeleteTransformFeedback(ctx, oldObj);
 103       }
 104
 105       *ptr = NULL;
 106    }
 107    assert(!*ptr);
 108
 109    if (obj) {
 110       /* reference new object */
 111       if (obj->RefCount == 0) {
 112          _mesa_problem(NULL, "referencing deleted transform feedback object");
 113          *ptr = NULL;
 114       }
 115       else {
 116          obj->RefCount++;
 117          obj->EverBound = GL_TRUE;
 118          *ptr = obj;
 119       }
 120    }
 121 }
 122
 123
 124 /**
 125  * Check that all the buffer objects currently bound for transform
 126  * feedback actually exist.  Raise a GL_INVALID_OPERATION error if
 127  * any buffers are missing.
 128  * \return GL_TRUE for success, GL_FALSE if error
 129  */
 130 GLboolean
 131 _mesa_validate_transform_feedback_buffers(struct gl_context *ctx)
 132 {
 133    /* XXX to do */
 134    return GL_TRUE;
 135 }
 136
 137
 138
 139 /**
 140  * Per-context init for transform feedback.
 141  */
 142 void
 143 _mesa_init_transform_feedback(struct gl_context *ctx)
 144 {
 145    /* core mesa expects this, even a dummy one, to be available */
 146    assert(ctx->Driver.NewTransformFeedback);
 147
 148    ctx->TransformFeedback.DefaultObject =
 149       ctx->Driver.NewTransformFeedback(ctx, 0);
 150
 151    assert(ctx->TransformFeedback.DefaultObject->RefCount == 1);
 152
 153    reference_transform_feedback_object(&ctx->TransformFeedback.CurrentObject,
 154                                        ctx->TransformFeedback.DefaultObject);
 155
 156    assert(ctx->TransformFeedback.DefaultObject->RefCount == 2);
 157
 158    ctx->TransformFeedback.Objects = _mesa_NewHashTable();
 159
 160    _mesa_reference_buffer_object(ctx,
 161                                  &ctx->TransformFeedback.CurrentBuffer,
 162                                  ctx->Shared->NullBufferObj);
 163 }
 164
 165
 166
 167 /**
 168  * Callback for _mesa_HashDeleteAll().
 169  */
 170 static void
 171 delete_cb(GLuint key, void *data, void *userData)
 172 {
 173    struct gl_context *ctx = (struct gl_context *) userData;
 174    struct gl_transform_feedback_object *obj =
 175       (struct gl_transform_feedback_object *) data;
 176
 177    ctx->Driver.DeleteTransformFeedback(ctx, obj);
 178 }
 179
 180
 181 /**
 182  * Per-context free/clean-up for transform feedback.
 183  */
 184 void
 185 _mesa_free_transform_feedback(struct gl_context *ctx)
 186 {
 187    /* core mesa expects this, even a dummy one, to be available */
 188    assert(ctx->Driver.NewTransformFeedback);
 189
 190    _mesa_reference_buffer_object(ctx,
 191                                  &ctx->TransformFeedback.CurrentBuffer,
 192                                  NULL);
 193
 194    /* Delete all feedback objects */
 195    _mesa_HashDeleteAll(ctx->TransformFeedback.Objects, delete_cb, ctx);
 196    _mesa_DeleteHashTable(ctx->TransformFeedback.Objects);
 197
 198    /* Delete the default feedback object */
 199    assert(ctx->Driver.DeleteTransformFeedback);
 200    ctx->Driver.DeleteTransformFeedback(ctx,
 201                                        ctx->TransformFeedback.DefaultObject);
 202
 203    ctx->TransformFeedback.CurrentObject = NULL;
 204 }
 205
 206
 207 /** Initialize the fields of a gl_transform_feedback_object. */
 208 void
 209 _mesa_init_transform_feedback_object(struct gl_transform_feedback_object *obj,
 210                                      GLuint name)
 211 {
 212    if (!obj)
 213       return;
 214
 215    obj->Name = name;
 216    obj->RefCount = 1;
 217    obj->EverBound = GL_FALSE;
 218 }
 219
 220
 221 /** Default fallback for ctx->Driver.NewTransformFeedback() */
 222 static struct gl_transform_feedback_object *
 223 new_transform_feedback(struct gl_context *ctx, GLuint name)
 224 {
 225    struct gl_transform_feedback_object *obj;
 226    obj = CALLOC_STRUCT(gl_transform_feedback_object);
 227    _mesa_init_transform_feedback_object(obj, name);
 228    return obj;
 229 }
 230
 231 /** Default fallback for ctx->Driver.DeleteTransformFeedback() */
 232 static void
 233 delete_transform_feedback(struct gl_context *ctx,
 234                           struct gl_transform_feedback_object *obj)
 235 {
 236    GLuint i;
 237
 238    for (i = 0; i < ARRAY_SIZE(obj->Buffers); i++) {
 239       _mesa_reference_buffer_object(ctx, &obj->Buffers[i], NULL);
 240    }
 241
 242    free(obj->Label);
 243    free(obj);
 244 }
 245
 246
 247 /** Default fallback for ctx->Driver.BeginTransformFeedback() */
 248 static void
 249 begin_transform_feedback(struct gl_context *ctx, GLenum mode,
 250                          struct gl_transform_feedback_object *obj)
 251 {
 252    /* nop */
 253 }
 254
 255 /** Default fallback for ctx->Driver.EndTransformFeedback() */
 256 static void
 257 end_transform_feedback(struct gl_context *ctx,
 258                        struct gl_transform_feedback_object *obj)
 259 {
 260    /* nop */
 261 }
 262
 263 /** Default fallback for ctx->Driver.PauseTransformFeedback() */
 264 static void
 265 pause_transform_feedback(struct gl_context *ctx,
 266                          struct gl_transform_feedback_object *obj)
 267 {
 268    /* nop */
 269 }
 270
 271 /** Default fallback for ctx->Driver.ResumeTransformFeedback() */
 272 static void
 273 resume_transform_feedback(struct gl_context *ctx,
 274                           struct gl_transform_feedback_object *obj)
 275 {
 276    /* nop */
 277 }
 278
 279
 280 /**
 281  * Plug in default device driver functions for transform feedback.
 282  * Most drivers will override some/all of these.
 283  */
 284 void
 285 _mesa_init_transform_feedback_functions(struct dd_function_table *driver)
 286 {
 287    driver->NewTransformFeedback = new_transform_feedback;
 288    driver->DeleteTransformFeedback = delete_transform_feedback;
 289    driver->BeginTransformFeedback = begin_transform_feedback;
 290    driver->EndTransformFeedback = end_transform_feedback;
 291    driver->PauseTransformFeedback = pause_transform_feedback;
 292    driver->ResumeTransformFeedback = resume_transform_feedback;
 293 }
 294
 295
 296 /**
 297  * Fill in the correct Size value for each buffer in \c obj.
 298  *
 299  * From the GL 4.3 spec, section 6.1.1 ("Binding Buffer Objects to Indexed
 300  * Targets"):
 301  *
 302  *   BindBufferBase binds the entire buffer, even when the size of the buffer
 303  *   is changed after the binding is established. It is equivalent to calling
 304  *   BindBufferRange with offset zero, while size is determined by the size of
 305  *   the bound buffer at the time the binding is used.
 306  *
 307  *   Regardless of the size specified with BindBufferRange, or indirectly with
 308  *   BindBufferBase, the GL will never read or write beyond the end of a bound
 309  *   buffer. In some cases this constraint may result in visibly different
 310  *   behavior when a buffer overflow would otherwise result, such as described
 311  *   for transform feedback operations in section 13.2.2.
 312  */
 313 static void
 314 compute_transform_feedback_buffer_sizes(
 315       struct gl_transform_feedback_object *obj)
 316 {
 317    unsigned i = 0;
 318    for (i = 0; i < MAX_FEEDBACK_BUFFERS; ++i) {
 319       GLintptr offset = obj->Offset[i];
 320       GLsizeiptr buffer_size
 321          = obj->Buffers[i] == NULL ? 0 : obj->Buffers[i]->Size;
 322       GLsizeiptr available_space
 323          = buffer_size <= offset ? 0 : buffer_size - offset;
 324       GLsizeiptr computed_size;
 325       if (obj->RequestedSize[i] == 0) {
 326          /* No size was specified at the time the buffer was bound, so allow
 327           * writing to all available space in the buffer.
 328           */
 329          computed_size = available_space;
 330       } else {
 331          /* A size was specified at the time the buffer was bound, however
 332           * it's possible that the buffer has shrunk since then.  So only
 333           * allow writing to the minimum of the specified size and the space
 334           * available.
 335           */
 336          computed_size = MIN2(available_space, obj->RequestedSize[i]);
 337       }
 338
 339       /* Legal sizes must be multiples of four, so round down if necessary. */
 340       obj->Size[i] = computed_size & ~0x3;
 341    }
 342 }
 343
 344
 345 /**
 346  * Compute the maximum number of vertices that can be written to the currently
 347  * enabled transform feedback buffers without overflowing any of them.
 348  */
 349 unsigned
 350 _mesa_compute_max_transform_feedback_vertices(
 351       const struct gl_transform_feedback_object *obj,
 352       const struct gl_transform_feedback_info *info)
 353 {
 354    unsigned max_index = 0xffffffff;
 355    unsigned i;
 356
 357    for (i = 0; i < info->NumBuffers; ++i) {
 358       unsigned stride = info->BufferStride[i];
 359       unsigned max_for_this_buffer;
 360
 361       /* Skip any inactive buffers, which have a stride of 0. */
 362       if (stride == 0)
 363          continue;
 364
 365       max_for_this_buffer = obj->Size[i] / (4 * stride);
 366       max_index = MIN2(max_index, max_for_this_buffer);
 367    }
 368
 369    return max_index;
 370 }
 371
 372
 373 /**
 374  ** Begin API functions
 375  **/
 376
 377
 378 /**
 379  * Figure out which stage of the pipeline is the source of transform feedback
 380  * data given the current context state, and return its gl_shader_program.
 381  *
 382  * If no active program can generate transform feedback data (i.e. no vertex
 383  * shader is active), returns NULL.
 384  */
 385 static struct gl_shader_program *
 386 get_xfb_source(struct gl_context *ctx)
 387 {
 388    int i;
 389    for (i = MESA_SHADER_GEOMETRY; i >= MESA_SHADER_VERTEX; i--) {
 390       if (ctx->_Shader->CurrentProgram[i] != NULL)
 391          return ctx->_Shader->CurrentProgram[i];
 392    }
 393    return NULL;
 394 }
 395
 396
 397 void GLAPIENTRY
 398 _mesa_BeginTransformFeedback(GLenum mode)
 399 {
 400    struct gl_transform_feedback_object *obj;
 401    struct gl_transform_feedback_info *info = NULL;
 402    struct gl_shader_program *source;
 403    GLuint i;
 404    unsigned vertices_per_prim;
 405    GET_CURRENT_CONTEXT(ctx);
 406
 407    obj = ctx->TransformFeedback.CurrentObject;
 408
 409    /* Figure out what pipeline stage is the source of data for transform
 410     * feedback.
 411     */
 412    source = get_xfb_source(ctx);
 413    if (source == NULL) {
 414       _mesa_error(ctx, GL_INVALID_OPERATION,
 415                   "glBeginTransformFeedback(no program active)");
 416       return;
 417    }
 418
 419    info = &source->LinkedTransformFeedback;
 420
 421    if (info->NumOutputs == 0) {
 422       _mesa_error(ctx, GL_INVALID_OPERATION,
 423                   "glBeginTransformFeedback(no varyings to record)");
 424       return;
 425    }
 426
 427    switch (mode) {
 428    case GL_POINTS:
 429       vertices_per_prim = 1;
 430       break;
 431    case GL_LINES:
 432       vertices_per_prim = 2;
 433       break;
 434    case GL_TRIANGLES:
 435       vertices_per_prim = 3;
 436       break;
 437    default:
 438       _mesa_error(ctx, GL_INVALID_ENUM, "glBeginTransformFeedback(mode)");
 439       return;
 440    }
 441
 442    if (obj->Active) {
 443       _mesa_error(ctx, GL_INVALID_OPERATION,
 444                   "glBeginTransformFeedback(already active)");
 445       return;
 446    }
 447
 448    for (i = 0; i < info->NumBuffers; ++i) {
 449       if (obj->BufferNames[i] == 0) {
 450          _mesa_error(ctx, GL_INVALID_OPERATION,
 451                      "glBeginTransformFeedback(binding point %d does not have "
 452                      "a buffer object bound)", i);
 453          return;
 454       }
 455    }
 456
 457    FLUSH_VERTICES(ctx, 0);
 458    ctx->NewDriverState |= ctx->DriverFlags.NewTransformFeedback;
 459
 460    obj->Active = GL_TRUE;
 461    ctx->TransformFeedback.Mode = mode;
 462
 463    compute_transform_feedback_buffer_sizes(obj);
 464
 465    if (_mesa_is_gles3(ctx)) {
 466       /* In GLES3, we are required to track the usage of the transform
 467        * feedback buffer and report INVALID_OPERATION if a draw call tries to
 468        * exceed it.  So compute the maximum number of vertices that we can
 469        * write without overflowing any of the buffers currently being used for
 470        * feedback.
 471        */
 472       unsigned max_vertices
 473          = _mesa_compute_max_transform_feedback_vertices(obj, info);
 474       obj->GlesRemainingPrims = max_vertices / vertices_per_prim;
 475    }
 476
 477    if (obj->shader_program != source) {
 478       ctx->NewDriverState |= ctx->DriverFlags.NewTransformFeedbackProg;
 479       obj->shader_program = source;
 480    }
 481
 482    assert(ctx->Driver.BeginTransformFeedback);
 483    ctx->Driver.BeginTransformFeedback(ctx, mode, obj);
 484 }
 485
 486
 487 void GLAPIENTRY
 488 _mesa_EndTransformFeedback(void)
 489 {
 490    struct gl_transform_feedback_object *obj;
 491    GET_CURRENT_CONTEXT(ctx);
 492
 493    obj = ctx->TransformFeedback.CurrentObject;
 494
 495    if (!obj->Active) {
 496       _mesa_error(ctx, GL_INVALID_OPERATION,
 497                   "glEndTransformFeedback(not active)");
 498       return;
 499    }
 500
 501    FLUSH_VERTICES(ctx, 0);
 502    ctx->NewDriverState |= ctx->DriverFlags.NewTransformFeedback;
 503
 504    ctx->TransformFeedback.CurrentObject->Active = GL_FALSE;
 505    ctx->TransformFeedback.CurrentObject->Paused = GL_FALSE;
 506    ctx->TransformFeedback.CurrentObject->EndedAnytime = GL_TRUE;
 507
 508    assert(ctx->Driver.EndTransformFeedback);
 509    ctx->Driver.EndTransformFeedback(ctx, obj);
 510 }
 511
 512
 513 /**
 514  * Helper used by BindBufferRange() and BindBufferBase().
 515  */
 516 static void
 517 bind_buffer_range(struct gl_context *ctx,
 518                   struct gl_transform_feedback_object *obj,
 519                   GLuint index,
 520                   struct gl_buffer_object *bufObj,
 521                   GLintptr offset, GLsizeiptr size,
 522                   bool dsa)
 523 {
 524    /* Note: no need to FLUSH_VERTICES or flag NewTransformFeedback, because
 525     * transform feedback buffers can't be changed while transform feedback is
 526     * active.
 527     */
 528
 529    if (!dsa) {
 530       /* The general binding point */
 531       _mesa_reference_buffer_object(ctx,
 532                                     &ctx->TransformFeedback.CurrentBuffer,
 533                                     bufObj);
 534    }
 535
 536    /* The per-attribute binding point */
 537    _mesa_set_transform_feedback_binding(ctx, obj, index, bufObj, offset, size);
 538 }
 539
 540
 541 /**
 542  * Specify a buffer object to receive transform feedback results.  Plus,
 543  * specify the starting offset to place the results, and max size.
 544  * Called from the glBindBufferRange() and glTransformFeedbackBufferRange
 545  * functions.
 546  */
 547 void
 548 _mesa_bind_buffer_range_transform_feedback(struct gl_context *ctx,
 549                                            struct gl_transform_feedback_object *obj,
 550                                            GLuint index,
 551                                            struct gl_buffer_object *bufObj,
 552                                            GLintptr offset,
 553                                            GLsizeiptr size,
 554                                            bool dsa)
 555 {
 556    const char *gl_methd_name;
 557    if (dsa)
 558       gl_methd_name = "glTransformFeedbackBufferRange";
 559    else
 560       gl_methd_name = "glBindBufferRange";
 561
 562
 563    if (obj->Active) {
 564       _mesa_error(ctx, GL_INVALID_OPERATION, "%s(transform feedback active)",
 565                   gl_methd_name);
 566       return;
 567    }
 568
 569    if (index >= ctx->Const.MaxTransformFeedbackBuffers) {
 570       /* OpenGL 4.5 core profile, 6.1, pdf page 82: "An INVALID_VALUE error is
 571        * generated if index is greater than or equal to the number of binding
 572        * points for transform feedback, as described in section 6.7.1."
 573        */
 574       _mesa_error(ctx, GL_INVALID_VALUE, "%s(index=%d out of bounds)",
 575                   gl_methd_name, index);
 576       return;
 577    }
 578
 579    if (size & 0x3) {
 580       /* OpenGL 4.5 core profile, 6.7, pdf page 103: multiple of 4 */
 581       _mesa_error(ctx, GL_INVALID_VALUE, "%s(size=%d must be a multiple of "
 582                   "four)", gl_methd_name, (int) size);
 583       return;
 584    }
 585
 586    if (offset & 0x3) {
 587       /* OpenGL 4.5 core profile, 6.7, pdf page 103: multiple of 4 */
 588       _mesa_error(ctx, GL_INVALID_VALUE, "%s(offset=%d must be a multiple "
 589                   "of four)", gl_methd_name, (int) offset);
 590       return;
 591    }
 592
 593    if (offset < 0) {
 594       /* OpenGL 4.5 core profile, 6.1, pdf page 82: "An INVALID_VALUE error is
 595        * generated by BindBufferRange if offset is negative."
 596        *
 597        * OpenGL 4.5 core profile, 13.2, pdf page 445: "An INVALID_VALUE error
 598        * is generated by TransformFeedbackBufferRange if offset is negative."
 599        */
 600       _mesa_error(ctx, GL_INVALID_VALUE, "%s(offset=%d must be >= 0)",
 601                   gl_methd_name,
 602                   (int) offset);
 603       return;
 604    }
 605
 606    if (size <= 0 && (dsa || bufObj != ctx->Shared->NullBufferObj)) {
 607       /* OpenGL 4.5 core profile, 6.1, pdf page 82: "An INVALID_VALUE error is
 608        * generated by BindBufferRange if buffer is non-zero and size is less
 609        * than or equal to zero."
 610        *
 611        * OpenGL 4.5 core profile, 13.2, pdf page 445: "An INVALID_VALUE error
 612        * is generated by TransformFeedbackBufferRange if size is less than or
 613        * equal to zero."
 614        */
 615       _mesa_error(ctx, GL_INVALID_VALUE, "%s(size=%d must be > 0)",
 616                   gl_methd_name, (int) size);
 617       return;
 618    }
 619
 620    bind_buffer_range(ctx, obj, index, bufObj, offset, size, dsa);
 621 }
 622
 623
 624 /**
 625  * Specify a buffer object to receive transform feedback results.
 626  * As above, but start at offset = 0.
 627  * Called from the glBindBufferBase() and glTransformFeedbackBufferBase()
 628  * functions.
 629  */
 630 void
 631 _mesa_bind_buffer_base_transform_feedback(struct gl_context *ctx,
 632                                           struct gl_transform_feedback_object *obj,
 633                                           GLuint index,
 634                                           struct gl_buffer_object *bufObj,
 635                                           bool dsa)
 636 {
 637    if (obj->Active) {
 638       _mesa_error(ctx, GL_INVALID_OPERATION,
 639                   "%s(transform feedback active)",
 640                   dsa ? "glTransformFeedbackBufferBase" : "glBindBufferBase");
 641       return;
 642    }
 643
 644    if (index >= ctx->Const.MaxTransformFeedbackBuffers) {
 645       _mesa_error(ctx, GL_INVALID_VALUE, "%s(index=%d out of bounds)",
 646                   dsa ? "glTransformFeedbackBufferBase" : "glBindBufferBase",
 647                   index);
 648       return;
 649    }
 650
 651    bind_buffer_range(ctx, obj, index, bufObj, 0, 0, dsa);
 652 }
 653
 654 /**
 655  * Wrapper around lookup_transform_feedback_object that throws
 656  * GL_INVALID_OPERATION if id is not in the hash table. After calling
 657  * _mesa_error, it returns NULL.
 658  */
 659 static struct gl_transform_feedback_object *
 660 lookup_transform_feedback_object_err(struct gl_context *ctx,
 661                                      GLuint xfb, const char* func)
 662 {
 663    struct gl_transform_feedback_object *obj;
 664
 665    obj = _mesa_lookup_transform_feedback_object(ctx, xfb);
 666    if (!obj) {
 667       _mesa_error(ctx, GL_INVALID_OPERATION,
 668                   "%s(xfb=%u: non-generated object name)", func, xfb);
 669    }
 670
 671    return obj;
 672 }
 673
 674 /**
 675  * Wrapper around _mesa_lookup_bufferobj that throws GL_INVALID_VALUE if id
 676  * is not in the hash table. Specialised version for the
 677  * transform-feedback-related functions. After calling _mesa_error, it
 678  * returns NULL.
 679  */
 680 static struct gl_buffer_object *
 681 lookup_transform_feedback_bufferobj_err(struct gl_context *ctx,
 682                                         GLuint buffer, const char* func)
 683 {
 684    struct gl_buffer_object *bufObj;
 685
 686    /* OpenGL 4.5 core profile, 13.2, pdf page 444: buffer must be zero or the
 687     * name of an existing buffer object.
 688     */
 689    if (buffer == 0) {
 690       bufObj = ctx->Shared->NullBufferObj;
 691    } else {
 692       bufObj = _mesa_lookup_bufferobj(ctx, buffer);
 693       if (!bufObj) {
 694          _mesa_error(ctx, GL_INVALID_VALUE, "%s(invalid buffer=%u)", func,
 695                      buffer);
 696       }
 697    }
 698
 699    return bufObj;
 700 }
 701
 702 void GLAPIENTRY
 703 _mesa_TransformFeedbackBufferBase(GLuint xfb, GLuint index, GLuint buffer)
 704 {
 705    GET_CURRENT_CONTEXT(ctx);
 706    struct gl_transform_feedback_object *obj;
 707    struct gl_buffer_object *bufObj;
 708
 709    if (!ctx->Extensions.ARB_direct_state_access) {
 710       _mesa_error(ctx, GL_INVALID_OPERATION,
 711                   "glTransformFeedbackBufferBase(GL_ARB_direct_state_access "
 712                   "is not supported)");
 713       return;
 714    }
 715
 716    obj = lookup_transform_feedback_object_err(ctx, xfb,
 717                                               "glTransformFeedbackBufferBase");
 718    if(!obj) {
 719       return;
 720    }
 721
 722    bufObj = lookup_transform_feedback_bufferobj_err(ctx, buffer,
 723                                               "glTransformFeedbackBufferBase");
 724    if(!bufObj) {
 725       return;
 726    }
 727
 728    _mesa_bind_buffer_base_transform_feedback(ctx, obj, index, bufObj, true);
 729 }
 730
 731 void GLAPIENTRY
 732 _mesa_TransformFeedbackBufferRange(GLuint xfb, GLuint index, GLuint buffer,
 733                                    GLintptr offset, GLsizeiptr size)
 734 {
 735    GET_CURRENT_CONTEXT(ctx);
 736    struct gl_transform_feedback_object *obj;
 737    struct gl_buffer_object *bufObj;
 738
 739    if (!ctx->Extensions.ARB_direct_state_access) {
 740       _mesa_error(ctx, GL_INVALID_OPERATION,
 741                   "glTransformFeedbackBufferRange(GL_ARB_direct_state_access "
 742                   "is not supported)");
 743       return;
 744    }
 745
 746    obj = lookup_transform_feedback_object_err(ctx, xfb,
 747                                               "glTransformFeedbackBufferRange");
 748    if(!obj) {
 749       return;
 750    }
 751
 752    bufObj = lookup_transform_feedback_bufferobj_err(ctx, buffer,
 753                                               "glTransformFeedbackBufferRange");
 754    if(!bufObj) {
 755       return;
 756    }
 757
 758    _mesa_bind_buffer_range_transform_feedback(ctx, obj, index, bufObj, offset,
 759                                               size, true);
 760 }
 761
 762 /**
 763  * Specify a buffer object to receive transform feedback results, plus the
 764  * offset in the buffer to start placing results.
 765  * This function is part of GL_EXT_transform_feedback, but not GL3.
 766  */
 767 void GLAPIENTRY
 768 _mesa_BindBufferOffsetEXT(GLenum target, GLuint index, GLuint buffer,
 769                           GLintptr offset)
 770 {
 771    struct gl_transform_feedback_object *obj;
 772    struct gl_buffer_object *bufObj;
 773    GET_CURRENT_CONTEXT(ctx);
 774
 775    if (target != GL_TRANSFORM_FEEDBACK_BUFFER) {
 776       _mesa_error(ctx, GL_INVALID_ENUM, "glBindBufferOffsetEXT(target)");
 777       return;
 778    }
 779
 780    obj = ctx->TransformFeedback.CurrentObject;
 781
 782    if (obj->Active) {
 783       _mesa_error(ctx, GL_INVALID_OPERATION,
 784                   "glBindBufferOffsetEXT(transform feedback active)");
 785       return;
 786    }
 787
 788    if (index >= ctx->Const.MaxTransformFeedbackBuffers) {
 789       _mesa_error(ctx, GL_INVALID_VALUE,
 790                   "glBindBufferOffsetEXT(index=%d)", index);
 791       return;
 792    }
 793
 794    if (offset & 0x3) {
 795       /* must be multiple of four */
 796       _mesa_error(ctx, GL_INVALID_VALUE,
 797                   "glBindBufferOffsetEXT(offset=%d)", (int) offset);
 798       return;
 799    }
 800
 801    if (buffer == 0) {
 802       bufObj = ctx->Shared->NullBufferObj;
 803    } else {
 804       bufObj = _mesa_lookup_bufferobj(ctx, buffer);
 805    }
 806
 807    if (!bufObj) {
 808       _mesa_error(ctx, GL_INVALID_OPERATION,
 809                   "glBindBufferOffsetEXT(invalid buffer=%u)", buffer);
 810       return;
 811    }
 812
 813    bind_buffer_range(ctx, obj, index, bufObj, offset, 0, false);
 814 }
 815
 816
 817 /**
 818  * This function specifies the transform feedback outputs to be written
 819  * to the feedback buffer(s), and in what order.
 820  */
 821 void GLAPIENTRY
 822 _mesa_TransformFeedbackVaryings(GLuint program, GLsizei count,
 823                                 const GLchar * const *varyings,
 824                                 GLenum bufferMode)
 825 {
 826    struct gl_shader_program *shProg;
 827    GLint i;
 828    GET_CURRENT_CONTEXT(ctx);
 829
 830    /* From the ARB_transform_feedback2 specification:
 831     * "The error INVALID_OPERATION is generated by TransformFeedbackVaryings
 832     *  if the current transform feedback object is active, even if paused."
 833     */
 834    if (ctx->TransformFeedback.CurrentObject->Active) {
 835       _mesa_error(ctx, GL_INVALID_OPERATION,
 836                "glTransformFeedbackVaryings(current object is active)");
 837       return;
 838    }
 839
 840    switch (bufferMode) {
 841    case GL_INTERLEAVED_ATTRIBS:
 842       break;
 843    case GL_SEPARATE_ATTRIBS:
 844       break;
 845    default:
 846       _mesa_error(ctx, GL_INVALID_ENUM,
 847                   "glTransformFeedbackVaryings(bufferMode)");
 848       return;
 849    }
 850
 851    if (count < 0 ||
 852        (bufferMode == GL_SEPARATE_ATTRIBS &&
 853         (GLuint) count > ctx->Const.MaxTransformFeedbackBuffers)) {
 854       _mesa_error(ctx, GL_INVALID_VALUE,
 855                   "glTransformFeedbackVaryings(count=%d)", count);
 856       return;
 857    }
 858
 859    shProg = _mesa_lookup_shader_program(ctx, program);
 860    if (!shProg) {
 861       _mesa_error(ctx, GL_INVALID_VALUE,
 862                   "glTransformFeedbackVaryings(program=%u)", program);
 863       return;
 864    }
 865
 866    if (ctx->Extensions.ARB_transform_feedback3) {
 867       if (bufferMode == GL_INTERLEAVED_ATTRIBS) {
 868          unsigned buffers = 1;
 869
 870          for (i = 0; i < count; i++) {
 871             if (strcmp(varyings[i], "gl_NextBuffer") == 0)
 872                buffers++;
 873          }
 874
 875          if (buffers > ctx->Const.MaxTransformFeedbackBuffers) {
 876             _mesa_error(ctx, GL_INVALID_OPERATION,
 877                         "glTransformFeedbackVaryings(too many gl_NextBuffer "
 878                         "occurences)");
 879             return;
 880          }
 881       } else {
 882          for (i = 0; i < count; i++) {
 883             if (strcmp(varyings[i], "gl_NextBuffer") == 0 ||
 884                 strcmp(varyings[i], "gl_SkipComponents1") == 0 ||
 885                 strcmp(varyings[i], "gl_SkipComponents2") == 0 ||
 886                 strcmp(varyings[i], "gl_SkipComponents3") == 0 ||
 887                 strcmp(varyings[i], "gl_SkipComponents4") == 0) {
 888                _mesa_error(ctx, GL_INVALID_OPERATION,
 889                            "glTransformFeedbackVaryings(SEPARATE_ATTRIBS,"
 890                            "varying=%s)",
 891                            varyings[i]);
 892                return;
 893             }
 894          }
 895       }
 896    }
 897
 898    /* free existing varyings, if any */
 899    for (i = 0; i < (GLint) shProg->TransformFeedback.NumVarying; i++) {
 900       free(shProg->TransformFeedback.VaryingNames[i]);
 901    }
 902    free(shProg->TransformFeedback.VaryingNames);
 903
 904    /* allocate new memory for varying names */
 905    shProg->TransformFeedback.VaryingNames =
 906       malloc(count * sizeof(GLchar *));
 907
 908    if (!shProg->TransformFeedback.VaryingNames) {
 909       _mesa_error(ctx, GL_OUT_OF_MEMORY, "glTransformFeedbackVaryings()");
 910       return;
 911    }
 912
 913    /* Save the new names and the count */
 914    for (i = 0; i < count; i++) {
 915       shProg->TransformFeedback.VaryingNames[i] = strdup(varyings[i]);
 916    }
 917    shProg->TransformFeedback.NumVarying = count;
 918
 919    shProg->TransformFeedback.BufferMode = bufferMode;
 920
 921    /* No need to invoke FLUSH_VERTICES or flag NewTransformFeedback since
 922     * the varyings won't be used until shader link time.
 923     */
 924 }
 925
 926
 927 /**
 928  * Get info about the transform feedback outputs which are to be written
 929  * to the feedback buffer(s).
 930  */
 931 void GLAPIENTRY
 932 _mesa_GetTransformFeedbackVarying(GLuint program, GLuint index,
 933                                   GLsizei bufSize, GLsizei *length,
 934                                   GLsizei *size, GLenum *type, GLchar *name)
 935 {
 936    const struct gl_shader_program *shProg;
 937    struct gl_program_resource *res;
 938    GET_CURRENT_CONTEXT(ctx);
 939
 940    shProg = _mesa_lookup_shader_program(ctx, program);
 941    if (!shProg) {
 942       _mesa_error(ctx, GL_INVALID_VALUE,
 943                   "glGetTransformFeedbackVarying(program=%u)", program);
 944       return;
 945    }
 946
 947    res = _mesa_program_resource_find_index((struct gl_shader_program *) shProg,
 948                                            GL_TRANSFORM_FEEDBACK_VARYING,
 949                                            index);
 950    if (!res) {
 951       _mesa_error(ctx, GL_INVALID_VALUE,
 952                   "glGetTransformFeedbackVarying(index=%u)", index);
 953       return;
 954    }
 955
 956    /* return the varying's name and length */
 957    _mesa_copy_string(name, bufSize, length, _mesa_program_resource_name(res));
 958
 959    /* return the datatype and value's size (in datatype units) */
 960    if (type)
 961       _mesa_program_resource_prop((struct gl_shader_program *) shProg,
 962                                   res, index, GL_TYPE, (GLint*) type,
 963                                   "glGetTransformFeedbackVarying");
 964    if (size)
 965       _mesa_program_resource_prop((struct gl_shader_program *) shProg,
 966                                   res, index, GL_ARRAY_SIZE, (GLint*) size,
 967                                   "glGetTransformFeedbackVarying");
 968 }
 969
 970
 971
 972 struct gl_transform_feedback_object *
 973 _mesa_lookup_transform_feedback_object(struct gl_context *ctx, GLuint name)
 974 {
 975    /* OpenGL 4.5 core profile, 13.2 pdf page 444: "xfb must be zero, indicating
 976     * the default transform feedback object, or the name of an existing
 977     * transform feedback object."
 978     */
 979    if (name == 0) {
 980       return ctx->TransformFeedback.DefaultObject;
 981    }
 982    else
 983       return (struct gl_transform_feedback_object *)
 984          _mesa_HashLookup(ctx->TransformFeedback.Objects, name);
 985 }
 986
 987 static void
 988 create_transform_feedbacks(struct gl_context *ctx, GLsizei n, GLuint *ids,
 989                            bool dsa)
 990 {
 991    GLuint first;
 992    const char* func;
 993
 994    if (dsa)
 995       func = "glCreateTransformFeedbacks";
 996    else
 997       func = "glGenTransformFeedbacks";
 998
 999    if (n < 0) {
1000       _mesa_error(ctx, GL_INVALID_VALUE, "%s(n < 0)", func);
1001       return;
1002    }
1003
1004    if (!ids)
1005       return;
1006
1007    /* we don't need contiguous IDs, but this might be faster */
1008    first = _mesa_HashFindFreeKeyBlock(ctx->TransformFeedback.Objects, n);
1009    if (first) {
1010       GLsizei i;
1011       for (i = 0; i < n; i++) {
1012          struct gl_transform_feedback_object *obj
1013             = ctx->Driver.NewTransformFeedback(ctx, first + i);
1014          if (!obj) {
1015             _mesa_error(ctx, GL_OUT_OF_MEMORY, "%s", func);
1016             return;
1017          }
1018          ids[i] = first + i;
1019          _mesa_HashInsert(ctx->TransformFeedback.Objects, first + i, obj);
1020          if (dsa) {
1021             /* this is normally done at bind time in the non-dsa case */
1022             obj->EverBound = GL_TRUE;
1023          }
1024       }
1025    }
1026    else {
1027       _mesa_error(ctx, GL_OUT_OF_MEMORY, "%s", func);
1028    }
1029 }
1030
1031 /**
1032  * Create new transform feedback objects.   Transform feedback objects
1033  * encapsulate the state related to transform feedback to allow quickly
1034  * switching state (and drawing the results, below).
1035  * Part of GL_ARB_transform_feedback2.
1036  */
1037 void GLAPIENTRY
1038 _mesa_GenTransformFeedbacks(GLsizei n, GLuint *names)
1039 {
1040    GET_CURRENT_CONTEXT(ctx);
1041
1042    /* GenTransformFeedbacks should just reserve the object names that a
1043     * subsequent call to BindTransformFeedback should actively create. For
1044     * the sake of simplicity, we reserve the names and create the objects
1045     * straight away.
1046     */
1047
1048    create_transform_feedbacks(ctx, n, names, false);
1049 }
1050
1051 /**
1052  * Create new transform feedback objects.   Transform feedback objects
1053  * encapsulate the state related to transform feedback to allow quickly
1054  * switching state (and drawing the results, below).
1055  * Part of GL_ARB_direct_state_access.
1056  */
1057 void GLAPIENTRY
1058 _mesa_CreateTransformFeedbacks(GLsizei n, GLuint *names)
1059 {
1060    GET_CURRENT_CONTEXT(ctx);
1061
1062    if (!ctx->Extensions.ARB_direct_state_access) {
1063       _mesa_error(ctx, GL_INVALID_OPERATION,
1064                   "glCreateTransformFeedbacks(GL_ARB_direct_state_access "
1065                   "is not supported)");
1066       return;
1067    }
1068
1069    create_transform_feedbacks(ctx, n, names, true);
1070 }
1071
1072
1073 /**
1074  * Is the given ID a transform feedback object?
1075  * Part of GL_ARB_transform_feedback2.
1076  */
1077 GLboolean GLAPIENTRY
1078 _mesa_IsTransformFeedback(GLuint name)
1079 {
1080    struct gl_transform_feedback_object *obj;
1081    GET_CURRENT_CONTEXT(ctx);
1082
1083    ASSERT_OUTSIDE_BEGIN_END_WITH_RETVAL(ctx, GL_FALSE);
1084
1085    if (name == 0)
1086       return GL_FALSE;
1087
1088    obj = _mesa_lookup_transform_feedback_object(ctx, name);
1089    if (obj == NULL)
1090       return GL_FALSE;
1091
1092    return obj->EverBound;
1093 }
1094
1095
1096 /**
1097  * Bind the given transform feedback object.
1098  * Part of GL_ARB_transform_feedback2.
1099  */
1100 void GLAPIENTRY
1101 _mesa_BindTransformFeedback(GLenum target, GLuint name)
1102 {
1103    struct gl_transform_feedback_object *obj;
1104    GET_CURRENT_CONTEXT(ctx);
1105
1106    if (target != GL_TRANSFORM_FEEDBACK) {
1107       _mesa_error(ctx, GL_INVALID_ENUM, "glBindTransformFeedback(target)");
1108       return;
1109    }
1110
1111    if (_mesa_is_xfb_active_and_unpaused(ctx)) {
1112       _mesa_error(ctx, GL_INVALID_OPERATION,
1113               "glBindTransformFeedback(transform is active, or not paused)");
1114       return;
1115    }
1116
1117    obj = _mesa_lookup_transform_feedback_object(ctx, name);
1118    if (!obj) {
1119       _mesa_error(ctx, GL_INVALID_OPERATION,
1120                   "glBindTransformFeedback(name=%u)", name);
1121       return;
1122    }
1123
1124    reference_transform_feedback_object(&ctx->TransformFeedback.CurrentObject,
1125                                        obj);
1126 }
1127
1128
1129 /**
1130  * Delete the given transform feedback objects.
1131  * Part of GL_ARB_transform_feedback2.
1132  */
1133 void GLAPIENTRY
1134 _mesa_DeleteTransformFeedbacks(GLsizei n, const GLuint *names)
1135 {
1136    GLint i;
1137    GET_CURRENT_CONTEXT(ctx);
1138
1139    if (n < 0) {
1140       _mesa_error(ctx, GL_INVALID_VALUE, "glDeleteTransformFeedbacks(n < 0)");
1141       return;
1142    }
1143
1144    if (!names)
1145       return;
1146
1147    for (i = 0; i < n; i++) {
1148       if (names[i] > 0) {
1149          struct gl_transform_feedback_object *obj
1150             = _mesa_lookup_transform_feedback_object(ctx, names[i]);
1151          if (obj) {
1152             if (obj->Active) {
1153                _mesa_error(ctx, GL_INVALID_OPERATION,
1154                            "glDeleteTransformFeedbacks(object %u is active)",
1155                            names[i]);
1156                return;
1157             }
1158             _mesa_HashRemove(ctx->TransformFeedback.Objects, names[i]);
1159             /* unref, but object may not be deleted until later */
1160             reference_transform_feedback_object(&obj, NULL);
1161          }
1162       }
1163    }
1164 }
1165
1166
1167 /**
1168  * Pause transform feedback.
1169  * Part of GL_ARB_transform_feedback2.
1170  */
1171 void GLAPIENTRY
1172 _mesa_PauseTransformFeedback(void)
1173 {
1174    struct gl_transform_feedback_object *obj;
1175    GET_CURRENT_CONTEXT(ctx);
1176
1177    obj = ctx->TransformFeedback.CurrentObject;
1178
1179    if (!_mesa_is_xfb_active_and_unpaused(ctx)) {
1180       _mesa_error(ctx, GL_INVALID_OPERATION,
1181            "glPauseTransformFeedback(feedback not active or already paused)");
1182       return;
1183    }
1184
1185    FLUSH_VERTICES(ctx, 0);
1186    ctx->NewDriverState |= ctx->DriverFlags.NewTransformFeedback;
1187
1188    obj->Paused = GL_TRUE;
1189
1190    assert(ctx->Driver.PauseTransformFeedback);
1191    ctx->Driver.PauseTransformFeedback(ctx, obj);
1192 }
1193
1194
1195 /**
1196  * Resume transform feedback.
1197  * Part of GL_ARB_transform_feedback2.
1198  */
1199 void GLAPIENTRY
1200 _mesa_ResumeTransformFeedback(void)
1201 {
1202    struct gl_transform_feedback_object *obj;
1203    GET_CURRENT_CONTEXT(ctx);
1204
1205    obj = ctx->TransformFeedback.CurrentObject;
1206
1207    if (!obj->Active || !obj->Paused) {
1208       _mesa_error(ctx, GL_INVALID_OPERATION,
1209                "glResumeTransformFeedback(feedback not active or not paused)");
1210       return;
1211    }
1212
1213    /* From the ARB_transform_feedback2 specification:
1214     * "The error INVALID_OPERATION is generated by ResumeTransformFeedback if
1215     *  the program object being used by the current transform feedback object
1216     *  is not active."
1217     */
1218    if (obj->shader_program != get_xfb_source(ctx)) {
1219       _mesa_error(ctx, GL_INVALID_OPERATION,
1220                   "glResumeTransformFeedback(wrong program bound)");
1221       return;
1222    }
1223
1224    FLUSH_VERTICES(ctx, 0);
1225    ctx->NewDriverState |= ctx->DriverFlags.NewTransformFeedback;
1226
1227    obj->Paused = GL_FALSE;
1228
1229    assert(ctx->Driver.ResumeTransformFeedback);
1230    ctx->Driver.ResumeTransformFeedback(ctx, obj);
1231 }
1232
1233 extern void GLAPIENTRY
1234 _mesa_GetTransformFeedbackiv(GLuint xfb, GLenum pname, GLint *param)
1235 {
1236     struct gl_transform_feedback_object *obj;
1237     GET_CURRENT_CONTEXT(ctx);
1238
1239     if (!ctx->Extensions.ARB_direct_state_access) {
1240        _mesa_error(ctx, GL_INVALID_OPERATION,
1241                    "glGetTransformFeedbackiv(GL_ARB_direct_state_access "
1242                    "is not supported)");
1243        return;
1244     }
1245
1246     obj = lookup_transform_feedback_object_err(ctx, xfb,
1247                                                "glGetTransformFeedbackiv");
1248     if(!obj) {
1249        return;
1250     }
1251
1252     switch(pname) {
1253     case GL_TRANSFORM_FEEDBACK_PAUSED:
1254        *param = obj->Paused;
1255        break;
1256     case GL_TRANSFORM_FEEDBACK_ACTIVE:
1257        *param = obj->Active;
1258        break;
1259     default:
1260        _mesa_error(ctx, GL_INVALID_ENUM,
1261                    "glGetTransformFeedbackiv(pname=%i)", pname);
1262     }
1263 }
1264
1265 extern void GLAPIENTRY
1266 _mesa_GetTransformFeedbacki_v(GLuint xfb, GLenum pname, GLuint index,
1267                               GLint *param)
1268 {
1269    struct gl_transform_feedback_object *obj;
1270    GET_CURRENT_CONTEXT(ctx);
1271
1272    if (!ctx->Extensions.ARB_direct_state_access) {
1273       _mesa_error(ctx, GL_INVALID_OPERATION,
1274                   "glGetTransformFeedbacki_v(GL_ARB_direct_state_access "
1275                   "is not supported)");
1276       return;
1277    }
1278
1279    obj = lookup_transform_feedback_object_err(ctx, xfb,
1280                                               "glGetTransformFeedbacki_v");
1281    if(!obj) {
1282       return;
1283    }
1284
1285    if (index >= ctx->Const.MaxTransformFeedbackBuffers) {
1286       _mesa_error(ctx, GL_INVALID_VALUE,
1287                   "glGetTransformFeedbacki_v(index=%i)", index);
1288       return;
1289    }
1290
1291    switch(pname) {
1292    case GL_TRANSFORM_FEEDBACK_BUFFER_BINDING:
1293       *param = obj->BufferNames[index];
1294       break;
1295    default:
1296       _mesa_error(ctx, GL_INVALID_ENUM,
1297                   "glGetTransformFeedbacki_v(pname=%i)", pname);
1298    }
1299 }
1300
1301 extern void GLAPIENTRY
1302 _mesa_GetTransformFeedbacki64_v(GLuint xfb, GLenum pname, GLuint index,
1303                                 GLint64 *param)
1304 {
1305    struct gl_transform_feedback_object *obj;
1306    GET_CURRENT_CONTEXT(ctx);
1307
1308    if (!ctx->Extensions.ARB_direct_state_access) {
1309       _mesa_error(ctx, GL_INVALID_OPERATION,
1310                   "glGetTransformFeedbacki64_v(GL_ARB_direct_state_access "
1311                   "is not supported)");
1312       return;
1313    }
1314
1315    obj = lookup_transform_feedback_object_err(ctx, xfb,
1316                                               "glGetTransformFeedbacki64_v");
1317    if(!obj) {
1318       return;
1319    }
1320
1321    if (index >= ctx->Const.MaxTransformFeedbackBuffers) {
1322       _mesa_error(ctx, GL_INVALID_VALUE,
1323                   "glGetTransformFeedbacki64_v(index=%i)", index);
1324       return;
1325    }
1326
1327    switch(pname) {
1328    case GL_TRANSFORM_FEEDBACK_BUFFER_START:
1329       *param = obj->Offset[index];
1330       break;
1331    case GL_TRANSFORM_FEEDBACK_BUFFER_SIZE:
1332       *param = obj->RequestedSize[index];
1333       break;
1334    default:
1335       _mesa_error(ctx, GL_INVALID_ENUM,
1336                   "glGetTransformFeedbacki64_v(pname=%i)", pname);
1337    }
1338 }