src/mesa/state_tracker/st_cb_fbo.c

   1 /**************************************************************************
   2  *
   3  * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
   4  * 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
   8  * "Software"), to deal in the Software without restriction, including
   9  * without limitation the rights to use, copy, modify, merge, publish,
  10  * distribute, sub license, and/or sell copies of the Software, and to
  11  * permit persons to whom the Software is furnished to do so, subject to
  12  * the following conditions:
  13  *
  14  * The above copyright notice and this permission notice (including the
  15  * next paragraph) shall be included in all copies or substantial portions
  16  * 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
  20  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
  21  * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
  22  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  23  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  24  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  **************************************************************************/
  27
  28
  29 /**
  30  * Framebuffer/renderbuffer functions.
  31  *
  32  * \author Brian Paul
  33  */
  34
  35
  36 #include "main/imports.h"
  37 #include "main/context.h"
  38 #include "main/fbobject.h"
  39 #include "main/framebuffer.h"
  40 #include "main/renderbuffer.h"
  41
  42 #include "pipe/p_context.h"
  43 #include "pipe/p_defines.h"
  44 #include "pipe/p_screen.h"
  45 #include "st_context.h"
  46 #include "st_cb_fbo.h"
  47 #include "st_cb_texture.h"
  48 #include "st_format.h"
  49 #include "st_public.h"
  50 #include "st_texture.h"
  51
  52 #include "util/u_format.h"
  53 #include "util/u_rect.h"
  54
  55
  56 /**
  57  * Compute the renderbuffer's Red/Green/EtcBit fields from the pipe format.
  58  */
  59 static int
  60 init_renderbuffer_bits(struct st_renderbuffer *strb,
  61                        enum pipe_format pipeFormat)
  62 {
  63    struct pipe_format_info info;
  64
  65    if (!st_get_format_info( pipeFormat, &info )) {
  66       assert( 0 );
  67    }
  68
  69    strb->Base.Format = info.mesa_format;
  70    strb->Base.DataType = st_format_datatype(pipeFormat);
  71
  72    return info.size;
  73 }
  74
  75 /**
  76  * gl_renderbuffer::AllocStorage()
  77  * This is called to allocate the original drawing surface, and
  78  * during window resize.
  79  */
  80 static GLboolean
  81 st_renderbuffer_alloc_storage(GLcontext * ctx, struct gl_renderbuffer *rb,
  82                               GLenum internalFormat,
  83                               GLuint width, GLuint height)
  84 {
  85    struct pipe_context *pipe = ctx->st->pipe;
  86    struct st_renderbuffer *strb = st_renderbuffer(rb);
  87    enum pipe_format format;
  88
  89    if (strb->format != PIPE_FORMAT_NONE)
  90       format = strb->format;
  91    else
  92       format = st_choose_renderbuffer_format(pipe->screen, internalFormat);
  93
  94    /* init renderbuffer fields */
  95    strb->Base.Width  = width;
  96    strb->Base.Height = height;
  97    init_renderbuffer_bits(strb, format);
  98
  99    strb->defined = GL_FALSE;  /* undefined contents now */
 100
 101    if(strb->software) {
 102       struct pipe_format_block block;
 103       size_t size;
 104
 105       _mesa_free(strb->data);
 106
 107       assert(strb->format != PIPE_FORMAT_NONE);
 108       pf_get_block(strb->format, &block);
 109
 110       strb->stride = pf_get_stride(&block, width);
 111       size = pf_get_2d_size(&block, strb->stride, height);
 112
 113       strb->data = _mesa_malloc(size);
 114
 115       return strb->data != NULL;
 116    }
 117    else {
 118       struct pipe_texture template;
 119       unsigned surface_usage;
 120
 121       /* Free the old surface and texture
 122        */
 123       pipe_surface_reference( &strb->surface, NULL );
 124       pipe_texture_reference( &strb->texture, NULL );
 125
 126       /* Setup new texture template.
 127        */
 128       memset(&template, 0, sizeof(template));
 129       template.target = PIPE_TEXTURE_2D;
 130       template.format = format;
 131       pf_get_block(format, &template.block);
 132       template.width0 = width;
 133       template.height0 = height;
 134       template.depth0 = 1;
 135       template.last_level = 0;
 136       template.nr_samples = rb->NumSamples;
 137       if (util_format_is_depth_or_stencil(format)) {
 138          template.tex_usage = PIPE_TEXTURE_USAGE_DEPTH_STENCIL;
 139       }
 140       else {
 141          template.tex_usage = (PIPE_TEXTURE_USAGE_DISPLAY_TARGET |
 142                                PIPE_TEXTURE_USAGE_RENDER_TARGET);
 143       }
 144
 145       /* Probably need dedicated flags for surface usage too:
 146        */
 147       surface_usage = (PIPE_BUFFER_USAGE_GPU_READ |
 148                        PIPE_BUFFER_USAGE_GPU_WRITE);
 149 #if 0
 150                        PIPE_BUFFER_USAGE_CPU_READ |
 151                        PIPE_BUFFER_USAGE_CPU_WRITE);
 152 #endif
 153
 154       strb->texture = pipe->screen->texture_create( pipe->screen,
 155                                                     &template );
 156
 157       if (!strb->texture)
 158          return FALSE;
 159
 160       strb->surface = pipe->screen->get_tex_surface( pipe->screen,
 161                                                      strb->texture,
 162                                                      0, 0, 0,
 163                                                      surface_usage );
 164       if (strb->surface) {
 165          assert(strb->surface->texture);
 166          assert(strb->surface->format);
 167          assert(strb->surface->width == width);
 168          assert(strb->surface->height == height);
 169       }
 170
 171       return strb->surface != NULL;
 172    }
 173 }
 174
 175
 176 /**
 177  * gl_renderbuffer::Delete()
 178  */
 179 static void
 180 st_renderbuffer_delete(struct gl_renderbuffer *rb)
 181 {
 182    struct st_renderbuffer *strb = st_renderbuffer(rb);
 183    ASSERT(strb);
 184    pipe_surface_reference(&strb->surface, NULL);
 185    pipe_texture_reference(&strb->texture, NULL);
 186    _mesa_free(strb->data);
 187    _mesa_free(strb);
 188 }
 189
 190
 191 /**
 192  * gl_renderbuffer::GetPointer()
 193  */
 194 static void *
 195 null_get_pointer(GLcontext * ctx, struct gl_renderbuffer *rb,
 196                  GLint x, GLint y)
 197 {
 198    /* By returning NULL we force all software rendering to go through
 199     * the span routines.
 200     */
 201 #if 0
 202    assert(0);  /* Should never get called with softpipe */
 203 #endif
 204    return NULL;
 205 }
 206
 207
 208 /**
 209  * Called via ctx->Driver.NewFramebuffer()
 210  */
 211 static struct gl_framebuffer *
 212 st_new_framebuffer(GLcontext *ctx, GLuint name)
 213 {
 214    /* XXX not sure we need to subclass gl_framebuffer for pipe */
 215    return _mesa_new_framebuffer(ctx, name);
 216 }
 217
 218
 219 /**
 220  * Called via ctx->Driver.NewRenderbuffer()
 221  */
 222 static struct gl_renderbuffer *
 223 st_new_renderbuffer(GLcontext *ctx, GLuint name)
 224 {
 225    struct st_renderbuffer *strb = ST_CALLOC_STRUCT(st_renderbuffer);
 226    if (strb) {
 227       _mesa_init_renderbuffer(&strb->Base, name);
 228       strb->Base.Delete = st_renderbuffer_delete;
 229       strb->Base.AllocStorage = st_renderbuffer_alloc_storage;
 230       strb->Base.GetPointer = null_get_pointer;
 231       strb->format = PIPE_FORMAT_NONE;
 232       return &strb->Base;
 233    }
 234    return NULL;
 235 }
 236
 237
 238 /**
 239  * Allocate a renderbuffer for a an on-screen window (not a user-created
 240  * renderbuffer).  The window system code determines the format.
 241  */
 242 struct gl_renderbuffer *
 243 st_new_renderbuffer_fb(enum pipe_format format, int samples, boolean sw)
 244 {
 245    struct st_renderbuffer *strb;
 246
 247    strb = ST_CALLOC_STRUCT(st_renderbuffer);
 248    if (!strb) {
 249       _mesa_error(NULL, GL_OUT_OF_MEMORY, "creating renderbuffer");
 250       return NULL;
 251    }
 252
 253    _mesa_init_renderbuffer(&strb->Base, 0);
 254    strb->Base.ClassID = 0x4242; /* just a unique value */
 255    strb->Base.NumSamples = samples;
 256    strb->format = format;
 257    init_renderbuffer_bits(strb, format);
 258    strb->software = sw;
 259
 260    switch (format) {
 261    case PIPE_FORMAT_A8R8G8B8_UNORM:
 262    case PIPE_FORMAT_B8G8R8A8_UNORM:
 263    case PIPE_FORMAT_X8R8G8B8_UNORM:
 264    case PIPE_FORMAT_B8G8R8X8_UNORM:
 265    case PIPE_FORMAT_A1R5G5B5_UNORM:
 266    case PIPE_FORMAT_A4R4G4B4_UNORM:
 267    case PIPE_FORMAT_R5G6B5_UNORM:
 268       strb->Base.InternalFormat = GL_RGBA;
 269       break;
 270    case PIPE_FORMAT_Z16_UNORM:
 271       strb->Base.InternalFormat = GL_DEPTH_COMPONENT16;
 272       break;
 273    case PIPE_FORMAT_Z32_UNORM:
 274       strb->Base.InternalFormat = GL_DEPTH_COMPONENT32;
 275       break;
 276    case PIPE_FORMAT_S8Z24_UNORM:
 277    case PIPE_FORMAT_Z24S8_UNORM:
 278    case PIPE_FORMAT_X8Z24_UNORM:
 279    case PIPE_FORMAT_Z24X8_UNORM:
 280       strb->Base.InternalFormat = GL_DEPTH24_STENCIL8_EXT;
 281       break;
 282    case PIPE_FORMAT_S8_UNORM:
 283       strb->Base.InternalFormat = GL_STENCIL_INDEX8_EXT;
 284       break;
 285    case PIPE_FORMAT_R16G16B16A16_SNORM:
 286       strb->Base.InternalFormat = GL_RGBA16;
 287       break;
 288    default:
 289       _mesa_problem(NULL,
 290                     "Unexpected format in st_new_renderbuffer_fb");
 291       _mesa_free(strb);
 292       return NULL;
 293    }
 294
 295    /* st-specific methods */
 296    strb->Base.Delete = st_renderbuffer_delete;
 297    strb->Base.AllocStorage = st_renderbuffer_alloc_storage;
 298    strb->Base.GetPointer = null_get_pointer;
 299
 300    /* surface is allocated in st_renderbuffer_alloc_storage() */
 301    strb->surface = NULL;
 302
 303    return &strb->Base;
 304 }
 305
 306
 307
 308
 309 /**
 310  * Called via ctx->Driver.BindFramebufferEXT().
 311  */
 312 static void
 313 st_bind_framebuffer(GLcontext *ctx, GLenum target,
 314                     struct gl_framebuffer *fb, struct gl_framebuffer *fbread)
 315 {
 316
 317 }
 318
 319 /**
 320  * Called by ctx->Driver.FramebufferRenderbuffer
 321  */
 322 static void
 323 st_framebuffer_renderbuffer(GLcontext *ctx,
 324                             struct gl_framebuffer *fb,
 325                             GLenum attachment,
 326                             struct gl_renderbuffer *rb)
 327 {
 328    /* XXX no need for derivation? */
 329    _mesa_framebuffer_renderbuffer(ctx, fb, attachment, rb);
 330 }
 331
 332
 333 /**
 334  * Called by ctx->Driver.RenderTexture
 335  */
 336 static void
 337 st_render_texture(GLcontext *ctx,
 338                   struct gl_framebuffer *fb,
 339                   struct gl_renderbuffer_attachment *att)
 340 {
 341    struct pipe_screen *screen = ctx->st->pipe->screen;
 342    struct st_renderbuffer *strb;
 343    struct gl_renderbuffer *rb;
 344    struct pipe_texture *pt = st_get_texobj_texture(att->Texture);
 345    struct st_texture_object *stObj;
 346    const struct gl_texture_image *texImage =
 347       att->Texture->Image[att->CubeMapFace][att->TextureLevel];
 348
 349    if (!pt)
 350       return;
 351
 352    /* create new renderbuffer which wraps the texture image */
 353    rb = st_new_renderbuffer(ctx, 0);
 354    if (!rb) {
 355       _mesa_error(ctx, GL_OUT_OF_MEMORY, "glFramebufferTexture()");
 356       return;
 357    }
 358
 359    _mesa_reference_renderbuffer(&att->Renderbuffer, rb);
 360    assert(rb->RefCount == 1);
 361    rb->AllocStorage = NULL; /* should not get called */
 362    strb = st_renderbuffer(rb);
 363
 364    assert(strb->Base.RefCount > 0);
 365
 366    /* get the texture for the texture object */
 367    stObj = st_texture_object(att->Texture);
 368
 369    /* point renderbuffer at texobject */
 370    strb->rtt = stObj;
 371    strb->rtt_level = att->TextureLevel;
 372    strb->rtt_face = att->CubeMapFace;
 373    strb->rtt_slice = att->Zoffset;
 374
 375    rb->Width = texImage->Width2;
 376    rb->Height = texImage->Height2;
 377    rb->_BaseFormat = texImage->_BaseFormat;
 378    /*printf("***** render to texture level %d: %d x %d\n", att->TextureLevel, rb->Width, rb->Height);*/
 379
 380    /*printf("***** pipe texture %d x %d\n", pt->width0, pt->height0);*/
 381
 382    pipe_texture_reference( &strb->texture, pt );
 383
 384    pipe_surface_reference(&strb->surface, NULL);
 385
 386    /* new surface for rendering into the texture */
 387    strb->surface = screen->get_tex_surface(screen,
 388                                            strb->texture,
 389                                            strb->rtt_face,
 390                                            strb->rtt_level,
 391                                            strb->rtt_slice,
 392                                            PIPE_BUFFER_USAGE_GPU_READ |
 393                                            PIPE_BUFFER_USAGE_GPU_WRITE);
 394
 395    init_renderbuffer_bits(strb, pt->format);
 396
 397    /*
 398    printf("RENDER TO TEXTURE obj=%p pt=%p surf=%p  %d x %d\n",
 399           att->Texture, pt, strb->surface, rb->Width, rb->Height);
 400    */
 401
 402    /* Invalidate buffer state so that the pipe's framebuffer state
 403     * gets updated.
 404     * That's where the new renderbuffer (which we just created) gets
 405     * passed to the pipe as a (color/depth) render target.
 406     */
 407    st_invalidate_state(ctx, _NEW_BUFFERS);
 408 }
 409
 410
 411 /**
 412  * Called via ctx->Driver.FinishRenderTexture.
 413  */
 414 static void
 415 st_finish_render_texture(GLcontext *ctx,
 416                          struct gl_renderbuffer_attachment *att)
 417 {
 418    struct st_renderbuffer *strb = st_renderbuffer(att->Renderbuffer);
 419
 420    if (!strb)
 421       return;
 422
 423    st_flush( ctx->st, PIPE_FLUSH_RENDER_CACHE, NULL );
 424
 425    if (strb->surface)
 426       pipe_surface_reference( &strb->surface, NULL );
 427
 428    strb->rtt = NULL;
 429
 430    /*
 431    printf("FINISH RENDER TO TEXTURE surf=%p\n", strb->surface);
 432    */
 433
 434    _mesa_reference_renderbuffer(&att->Renderbuffer, NULL);
 435
 436    /* restore previous framebuffer state */
 437    st_invalidate_state(ctx, _NEW_BUFFERS);
 438 }
 439
 440
 441 /**
 442  * Validate a renderbuffer attachment for a particular usage.
 443  */
 444
 445 static GLboolean
 446 st_validate_attachment(struct pipe_screen *screen,
 447                        const struct gl_renderbuffer_attachment *att,
 448                        GLuint usage)
 449 {
 450    const struct st_texture_object *stObj =
 451       st_texture_object(att->Texture);
 452
 453    /**
 454     * Only validate texture attachments for now, since
 455     * st_renderbuffer_alloc_storage makes sure that
 456     * the format is supported.
 457     */
 458
 459    if (att->Type != GL_TEXTURE)
 460       return GL_TRUE;
 461
 462    if (!stObj)
 463       return GL_FALSE;
 464
 465    return screen->is_format_supported(screen, stObj->pt->format,
 466                                       PIPE_TEXTURE_2D,
 467                                       usage, 0);
 468 }
 469
 470 /**
 471  * Check that the framebuffer configuration is valid in terms of what
 472  * the driver can support.
 473  *
 474  * For Gallium we only supports combined Z+stencil, not separate buffers.
 475  */
 476 static void
 477 st_validate_framebuffer(GLcontext *ctx, struct gl_framebuffer *fb)
 478 {
 479    struct pipe_screen *screen = ctx->st->pipe->screen;
 480    const struct gl_renderbuffer *depthRb =
 481       fb->Attachment[BUFFER_DEPTH].Renderbuffer;
 482    const struct gl_renderbuffer *stencilRb =
 483       fb->Attachment[BUFFER_STENCIL].Renderbuffer;
 484    GLuint i;
 485
 486    if (stencilRb && depthRb && stencilRb != depthRb) {
 487       fb->_Status = GL_FRAMEBUFFER_UNSUPPORTED_EXT;
 488       return;
 489    }
 490
 491    if (!st_validate_attachment(screen,
 492                                &fb->Attachment[BUFFER_DEPTH],
 493                                PIPE_TEXTURE_USAGE_DEPTH_STENCIL)) {
 494       fb->_Status = GL_FRAMEBUFFER_UNSUPPORTED_EXT;
 495       return;
 496    }
 497    if (!st_validate_attachment(screen,
 498                                &fb->Attachment[BUFFER_STENCIL],
 499                                PIPE_TEXTURE_USAGE_DEPTH_STENCIL)) {
 500       fb->_Status = GL_FRAMEBUFFER_UNSUPPORTED_EXT;
 501       return;
 502    }
 503    for (i = 0; i < ctx->Const.MaxColorAttachments; i++) {
 504       if (!st_validate_attachment(screen,
 505                                   &fb->Attachment[BUFFER_COLOR0 + i],
 506                                   PIPE_TEXTURE_USAGE_RENDER_TARGET)) {
 507          fb->_Status = GL_FRAMEBUFFER_UNSUPPORTED_EXT;
 508          return;
 509       }
 510    }
 511 }
 512
 513
 514 /**
 515  * Copy back color buffer to front color buffer.
 516  */
 517 static void
 518 copy_back_to_front(struct st_context *st,
 519                    struct gl_framebuffer *fb,
 520                    gl_buffer_index frontIndex,
 521                    gl_buffer_index backIndex)
 522
 523 {
 524    struct st_framebuffer *stfb = (struct st_framebuffer *) fb;
 525    struct pipe_surface *surf_front, *surf_back;
 526
 527    (void) st_get_framebuffer_surface(stfb, frontIndex, &surf_front);
 528    (void) st_get_framebuffer_surface(stfb, backIndex, &surf_back);
 529
 530    if (surf_front && surf_back) {
 531       if (st->pipe->surface_copy) {
 532          st->pipe->surface_copy(st->pipe,
 533                                 surf_front, 0, 0,  /* dest */
 534                                 surf_back, 0, 0,   /* src */
 535                                 fb->Width, fb->Height);
 536       } else {
 537          util_surface_copy(st->pipe, FALSE,
 538                            surf_front, 0, 0,
 539                            surf_back, 0, 0,
 540                            fb->Width, fb->Height);
 541       }
 542    }
 543 }
 544
 545
 546 /**
 547  * Check if we're drawing into, or read from, a front color buffer.  If the
 548  * front buffer is missing, create it now.
 549  *
 550  * The back color buffer must exist since we'll use its format/samples info
 551  * for creating the front buffer.
 552  *
 553  * \param frontIndex  either BUFFER_FRONT_LEFT or BUFFER_FRONT_RIGHT
 554  * \param backIndex  either BUFFER_BACK_LEFT or BUFFER_BACK_RIGHT
 555  */
 556 static void
 557 check_create_front_buffer(GLcontext *ctx, struct gl_framebuffer *fb,
 558                           gl_buffer_index frontIndex,
 559                           gl_buffer_index backIndex)
 560 {
 561    if (fb->Attachment[frontIndex].Renderbuffer == NULL) {
 562       GLboolean create = GL_FALSE;
 563
 564       /* check if drawing to or reading from front buffer */
 565       if (fb->_ColorReadBufferIndex == frontIndex) {
 566          create = GL_TRUE;
 567       }
 568       else {
 569          GLuint b;
 570          for (b = 0; b < fb->_NumColorDrawBuffers; b++) {
 571             if (fb->_ColorDrawBufferIndexes[b] == frontIndex) {
 572                create = GL_TRUE;
 573                break;
 574             }
 575          }
 576       }
 577
 578       if (create) {
 579          struct st_renderbuffer *back;
 580          struct gl_renderbuffer *front;
 581          enum pipe_format colorFormat;
 582          uint samples;
 583
 584          if (0)
 585             _mesa_debug(ctx, "Allocate new front buffer\n");
 586
 587          /* get back renderbuffer info */
 588          back = st_renderbuffer(fb->Attachment[backIndex].Renderbuffer);
 589          colorFormat = back->format;
 590          samples = back->Base.NumSamples;
 591
 592          /* create front renderbuffer */
 593          front = st_new_renderbuffer_fb(colorFormat, samples, FALSE);
 594          _mesa_add_renderbuffer(fb, frontIndex, front);
 595
 596          /* alloc texture/surface for new front buffer */
 597          front->AllocStorage(ctx, front, front->InternalFormat,
 598                              fb->Width, fb->Height);
 599
 600          /* initialize the front color buffer contents by copying
 601           * the back buffer.
 602           */
 603          copy_back_to_front(ctx->st, fb, frontIndex, backIndex);
 604       }
 605    }
 606 }
 607
 608
 609 /**
 610  * If front left/right color buffers are missing, create them now.
 611  */
 612 static void
 613 check_create_front_buffers(GLcontext *ctx, struct gl_framebuffer *fb)
 614 {
 615    /* check if we need to create the front left buffer now */
 616    check_create_front_buffer(ctx, fb, BUFFER_FRONT_LEFT, BUFFER_BACK_LEFT);
 617
 618    if (fb->Visual.stereoMode) {
 619       check_create_front_buffer(ctx, fb, BUFFER_FRONT_RIGHT, BUFFER_BACK_RIGHT);
 620    }
 621
 622    st_invalidate_state(ctx, _NEW_BUFFERS);
 623 }
 624
 625
 626 /**
 627  * Called via glDrawBuffer.
 628  */
 629 static void
 630 st_DrawBuffers(GLcontext *ctx, GLsizei count, const GLenum *buffers)
 631 {
 632    (void) count;
 633    (void) buffers;
 634    check_create_front_buffers(ctx, ctx->DrawBuffer);
 635 }
 636
 637
 638 /**
 639  * Called via glReadBuffer.
 640  */
 641 static void
 642 st_ReadBuffer(GLcontext *ctx, GLenum buffer)
 643 {
 644    (void) buffer;
 645    check_create_front_buffers(ctx, ctx->ReadBuffer);
 646 }
 647
 648
 649 void st_init_fbo_functions(struct dd_function_table *functions)
 650 {
 651    functions->NewFramebuffer = st_new_framebuffer;
 652    functions->NewRenderbuffer = st_new_renderbuffer;
 653    functions->BindFramebuffer = st_bind_framebuffer;
 654    functions->FramebufferRenderbuffer = st_framebuffer_renderbuffer;
 655    functions->RenderTexture = st_render_texture;
 656    functions->FinishRenderTexture = st_finish_render_texture;
 657    functions->ValidateFramebuffer = st_validate_framebuffer;
 658    /* no longer needed by core Mesa, drivers handle resizes...
 659    functions->ResizeBuffers = st_resize_buffers;
 660    */
 661
 662    functions->DrawBuffers = st_DrawBuffers;
 663    functions->ReadBuffer = st_ReadBuffer;
 664 }