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/macros.h"
  41 #include "main/mfeatures.h"
  42 #include "main/renderbuffer.h"
  43
  44 #include "pipe/p_context.h"
  45 #include "pipe/p_defines.h"
  46 #include "pipe/p_screen.h"
  47 #include "st_context.h"
  48 #include "st_cb_fbo.h"
  49 #include "st_cb_flush.h"
  50 #include "st_format.h"
  51 #include "st_texture.h"
  52 #include "st_manager.h"
  53
  54 #include "util/u_format.h"
  55 #include "util/u_inlines.h"
  56 #include "util/u_surface.h"
  57
  58
  59 /**
  60  * gl_renderbuffer::AllocStorage()
  61  * This is called to allocate the original drawing surface, and
  62  * during window resize.
  63  */
  64 static GLboolean
  65 st_renderbuffer_alloc_storage(struct gl_context * ctx,
  66                               struct gl_renderbuffer *rb,
  67                               GLenum internalFormat,
  68                               GLuint width, GLuint height)
  69 {
  70    struct st_context *st = st_context(ctx);
  71    struct pipe_context *pipe = st->pipe;
  72    struct pipe_screen *screen = st->pipe->screen;
  73    struct st_renderbuffer *strb = st_renderbuffer(rb);
  74    enum pipe_format format;
  75    struct pipe_surface surf_tmpl;
  76
  77    if (strb->format != PIPE_FORMAT_NONE)
  78       format = strb->format;
  79    else
  80       format = st_choose_renderbuffer_format(screen, internalFormat,
  81                                              rb->NumSamples);
  82
  83    if (format == PIPE_FORMAT_NONE) {
  84       return FALSE;
  85    }
  86
  87    /* init renderbuffer fields */
  88    strb->Base.Width  = width;
  89    strb->Base.Height = height;
  90    strb->Base.Format = st_pipe_format_to_mesa_format(format);
  91    strb->Base._BaseFormat = _mesa_base_fbo_format(ctx, internalFormat);
  92    strb->Base.DataType = st_format_datatype(format);
  93
  94    strb->defined = GL_FALSE;  /* undefined contents now */
  95
  96    if (strb->software) {
  97       size_t size;
  98
  99       free(strb->data);
 100
 101       assert(strb->format != PIPE_FORMAT_NONE);
 102
 103       strb->stride = util_format_get_stride(strb->format, width);
 104       size = util_format_get_2d_size(strb->format, strb->stride, height);
 105
 106       strb->data = malloc(size);
 107
 108       return strb->data != NULL;
 109    }
 110    else {
 111       struct pipe_resource template;
 112
 113       /* Free the old surface and texture
 114        */
 115       pipe_surface_reference( &strb->surface, NULL );
 116       pipe_resource_reference( &strb->texture, NULL );
 117       pipe_sampler_view_reference(&strb->sampler_view, NULL);
 118
 119       /* Setup new texture template.
 120        */
 121       memset(&template, 0, sizeof(template));
 122       template.target = st->internal_target;
 123       template.format = format;
 124       template.width0 = width;
 125       template.height0 = height;
 126       template.depth0 = 1;
 127       template.array_size = 1;
 128       template.last_level = 0;
 129       template.nr_samples = rb->NumSamples;
 130       if (util_format_is_depth_or_stencil(format)) {
 131          template.bind = PIPE_BIND_DEPTH_STENCIL;
 132       }
 133       else {
 134          template.bind = (PIPE_BIND_DISPLAY_TARGET |
 135                           PIPE_BIND_RENDER_TARGET);
 136       }
 137
 138       strb->texture = screen->resource_create(screen, &template);
 139
 140       if (!strb->texture)
 141          return FALSE;
 142
 143       memset(&surf_tmpl, 0, sizeof(surf_tmpl));
 144       u_surface_default_template(&surf_tmpl, strb->texture, template.bind);
 145       strb->surface = pipe->create_surface(pipe,
 146                                            strb->texture,
 147                                            &surf_tmpl);
 148       if (strb->surface) {
 149          assert(strb->surface->texture);
 150          assert(strb->surface->format);
 151          assert(strb->surface->width == width);
 152          assert(strb->surface->height == height);
 153       }
 154
 155       return strb->surface != NULL;
 156    }
 157 }
 158
 159
 160 /**
 161  * gl_renderbuffer::Delete()
 162  */
 163 static void
 164 st_renderbuffer_delete(struct gl_renderbuffer *rb)
 165 {
 166    struct st_renderbuffer *strb = st_renderbuffer(rb);
 167    ASSERT(strb);
 168    pipe_surface_reference(&strb->surface, NULL);
 169    pipe_resource_reference(&strb->texture, NULL);
 170    pipe_sampler_view_reference(&strb->sampler_view, NULL);
 171    free(strb->data);
 172    free(strb);
 173 }
 174
 175
 176 /**
 177  * gl_renderbuffer::GetPointer()
 178  */
 179 static void *
 180 null_get_pointer(struct gl_context * ctx, struct gl_renderbuffer *rb,
 181                  GLint x, GLint y)
 182 {
 183    /* By returning NULL we force all software rendering to go through
 184     * the span routines.
 185     */
 186 #if 0
 187    assert(0);  /* Should never get called with softpipe */
 188 #endif
 189    return NULL;
 190 }
 191
 192
 193 /**
 194  * Called via ctx->Driver.NewFramebuffer()
 195  */
 196 static struct gl_framebuffer *
 197 st_new_framebuffer(struct gl_context *ctx, GLuint name)
 198 {
 199    /* XXX not sure we need to subclass gl_framebuffer for pipe */
 200    return _mesa_new_framebuffer(ctx, name);
 201 }
 202
 203
 204 /**
 205  * Called via ctx->Driver.NewRenderbuffer()
 206  */
 207 static struct gl_renderbuffer *
 208 st_new_renderbuffer(struct gl_context *ctx, GLuint name)
 209 {
 210    struct st_renderbuffer *strb = ST_CALLOC_STRUCT(st_renderbuffer);
 211    if (strb) {
 212       _mesa_init_renderbuffer(&strb->Base, name);
 213       strb->Base.Delete = st_renderbuffer_delete;
 214       strb->Base.AllocStorage = st_renderbuffer_alloc_storage;
 215       strb->Base.GetPointer = null_get_pointer;
 216       strb->format = PIPE_FORMAT_NONE;
 217       return &strb->Base;
 218    }
 219    return NULL;
 220 }
 221
 222
 223 /**
 224  * Allocate a renderbuffer for a an on-screen window (not a user-created
 225  * renderbuffer).  The window system code determines the format.
 226  */
 227 struct gl_renderbuffer *
 228 st_new_renderbuffer_fb(enum pipe_format format, int samples, boolean sw)
 229 {
 230    struct st_renderbuffer *strb;
 231
 232    strb = ST_CALLOC_STRUCT(st_renderbuffer);
 233    if (!strb) {
 234       _mesa_error(NULL, GL_OUT_OF_MEMORY, "creating renderbuffer");
 235       return NULL;
 236    }
 237
 238    _mesa_init_renderbuffer(&strb->Base, 0);
 239    strb->Base.ClassID = 0x4242; /* just a unique value */
 240    strb->Base.NumSamples = samples;
 241    strb->Base.Format = st_pipe_format_to_mesa_format(format);
 242    strb->Base._BaseFormat = _mesa_get_format_base_format(strb->Base.Format);
 243    strb->Base.DataType = st_format_datatype(format);
 244    strb->format = format;
 245    strb->software = sw;
 246
 247    switch (format) {
 248    case PIPE_FORMAT_R8G8B8A8_UNORM:
 249    case PIPE_FORMAT_B8G8R8A8_UNORM:
 250    case PIPE_FORMAT_A8R8G8B8_UNORM:
 251    case PIPE_FORMAT_R8G8B8X8_UNORM:
 252    case PIPE_FORMAT_B8G8R8X8_UNORM:
 253    case PIPE_FORMAT_X8R8G8B8_UNORM:
 254    case PIPE_FORMAT_B5G5R5A1_UNORM:
 255    case PIPE_FORMAT_B4G4R4A4_UNORM:
 256    case PIPE_FORMAT_B5G6R5_UNORM:
 257       strb->Base.InternalFormat = GL_RGBA;
 258       break;
 259    case PIPE_FORMAT_Z16_UNORM:
 260       strb->Base.InternalFormat = GL_DEPTH_COMPONENT16;
 261       break;
 262    case PIPE_FORMAT_Z32_UNORM:
 263       strb->Base.InternalFormat = GL_DEPTH_COMPONENT32;
 264       break;
 265    case PIPE_FORMAT_Z24_UNORM_S8_USCALED:
 266    case PIPE_FORMAT_S8_USCALED_Z24_UNORM:
 267    case PIPE_FORMAT_Z24X8_UNORM:
 268    case PIPE_FORMAT_X8Z24_UNORM:
 269       strb->Base.InternalFormat = GL_DEPTH24_STENCIL8_EXT;
 270       break;
 271    case PIPE_FORMAT_S8_USCALED:
 272       strb->Base.InternalFormat = GL_STENCIL_INDEX8_EXT;
 273       break;
 274    case PIPE_FORMAT_R16G16B16A16_SNORM:
 275       strb->Base.InternalFormat = GL_RGBA16;
 276       break;
 277    case PIPE_FORMAT_R8_UNORM:
 278       strb->Base.InternalFormat = GL_R8;
 279       break;
 280    case PIPE_FORMAT_R8G8_UNORM:
 281       strb->Base.InternalFormat = GL_RG8;
 282       break;
 283    case PIPE_FORMAT_R16_UNORM:
 284       strb->Base.InternalFormat = GL_R16;
 285       break;
 286    case PIPE_FORMAT_R16G16_UNORM:
 287       strb->Base.InternalFormat = GL_RG16;
 288       break;
 289    default:
 290       _mesa_problem(NULL,
 291                     "Unexpected format in st_new_renderbuffer_fb");
 292       free(strb);
 293       return NULL;
 294    }
 295
 296    /* st-specific methods */
 297    strb->Base.Delete = st_renderbuffer_delete;
 298    strb->Base.AllocStorage = st_renderbuffer_alloc_storage;
 299    strb->Base.GetPointer = null_get_pointer;
 300
 301    /* surface is allocated in st_renderbuffer_alloc_storage() */
 302    strb->surface = NULL;
 303
 304    return &strb->Base;
 305 }
 306
 307
 308
 309
 310 /**
 311  * Called via ctx->Driver.BindFramebufferEXT().
 312  */
 313 static void
 314 st_bind_framebuffer(struct gl_context *ctx, GLenum target,
 315                     struct gl_framebuffer *fb, struct gl_framebuffer *fbread)
 316 {
 317
 318 }
 319
 320 /**
 321  * Called by ctx->Driver.FramebufferRenderbuffer
 322  */
 323 static void
 324 st_framebuffer_renderbuffer(struct gl_context *ctx,
 325                             struct gl_framebuffer *fb,
 326                             GLenum attachment,
 327                             struct gl_renderbuffer *rb)
 328 {
 329    /* XXX no need for derivation? */
 330    _mesa_framebuffer_renderbuffer(ctx, fb, attachment, rb);
 331 }
 332
 333
 334 /**
 335  * Called by ctx->Driver.RenderTexture
 336  */
 337 static void
 338 st_render_texture(struct gl_context *ctx,
 339                   struct gl_framebuffer *fb,
 340                   struct gl_renderbuffer_attachment *att)
 341 {
 342    struct st_context *st = st_context(ctx);
 343    struct pipe_context *pipe = st->pipe;
 344    struct st_renderbuffer *strb;
 345    struct gl_renderbuffer *rb;
 346    struct pipe_resource *pt = st_get_texobj_resource(att->Texture);
 347    struct st_texture_object *stObj;
 348    const struct gl_texture_image *texImage;
 349    struct pipe_surface surf_tmpl;
 350
 351    /* When would this fail?  Perhaps assert? */
 352    if (!pt)
 353       return;
 354
 355    /* get pointer to texture image we're rendeing to */
 356    texImage = att->Texture->Image[att->CubeMapFace][att->TextureLevel];
 357
 358    /* create new renderbuffer which wraps the texture image */
 359    rb = st_new_renderbuffer(ctx, 0);
 360    if (!rb) {
 361       _mesa_error(ctx, GL_OUT_OF_MEMORY, "glFramebufferTexture()");
 362       return;
 363    }
 364
 365    _mesa_reference_renderbuffer(&att->Renderbuffer, rb);
 366    assert(rb->RefCount == 1);
 367    rb->AllocStorage = NULL; /* should not get called */
 368    strb = st_renderbuffer(rb);
 369
 370    assert(strb->Base.RefCount > 0);
 371
 372    /* get the texture for the texture object */
 373    stObj = st_texture_object(att->Texture);
 374
 375    /* point renderbuffer at texobject */
 376    strb->rtt = stObj;
 377    strb->rtt_level = att->TextureLevel;
 378    strb->rtt_face = att->CubeMapFace;
 379    strb->rtt_slice = att->Zoffset;
 380
 381    rb->Width = texImage->Width2;
 382    rb->Height = texImage->Height2;
 383    rb->_BaseFormat = texImage->_BaseFormat;
 384    /*printf("***** render to texture level %d: %d x %d\n", att->TextureLevel, rb->Width, rb->Height);*/
 385
 386    /*printf("***** pipe texture %d x %d\n", pt->width0, pt->height0);*/
 387
 388    pipe_resource_reference( &strb->texture, pt );
 389
 390    pipe_surface_reference(&strb->surface, NULL);
 391
 392    pipe_sampler_view_reference(&strb->sampler_view,
 393                                st_get_texture_sampler_view(stObj, pipe));
 394
 395    assert(strb->rtt_level <= strb->texture->last_level);
 396
 397    /* new surface for rendering into the texture */
 398    memset(&surf_tmpl, 0, sizeof(surf_tmpl));
 399    surf_tmpl.format = ctx->Color.sRGBEnabled ? strb->texture->format : util_format_linear(strb->texture->format);
 400    surf_tmpl.usage = PIPE_BIND_RENDER_TARGET;
 401    surf_tmpl.u.tex.level = strb->rtt_level;
 402    surf_tmpl.u.tex.first_layer = strb->rtt_face + strb->rtt_slice;
 403    surf_tmpl.u.tex.last_layer = strb->rtt_face + strb->rtt_slice;
 404    strb->surface = pipe->create_surface(pipe,
 405                                         strb->texture,
 406                                         &surf_tmpl);
 407
 408    strb->format = pt->format;
 409
 410    strb->Base.Format = st_pipe_format_to_mesa_format(pt->format);
 411    strb->Base.DataType = st_format_datatype(pt->format);
 412
 413    /*
 414    printf("RENDER TO TEXTURE obj=%p pt=%p surf=%p  %d x %d\n",
 415           att->Texture, pt, strb->surface, rb->Width, rb->Height);
 416    */
 417
 418    /* Invalidate buffer state so that the pipe's framebuffer state
 419     * gets updated.
 420     * That's where the new renderbuffer (which we just created) gets
 421     * passed to the pipe as a (color/depth) render target.
 422     */
 423    st_invalidate_state(ctx, _NEW_BUFFERS);
 424 }
 425
 426
 427 /**
 428  * Called via ctx->Driver.FinishRenderTexture.
 429  */
 430 static void
 431 st_finish_render_texture(struct gl_context *ctx,
 432                          struct gl_renderbuffer_attachment *att)
 433 {
 434    struct st_context *st = st_context(ctx);
 435    struct st_renderbuffer *strb = st_renderbuffer(att->Renderbuffer);
 436
 437    if (!strb)
 438       return;
 439
 440    st_flush(st, PIPE_FLUSH_RENDER_CACHE, NULL);
 441
 442    strb->rtt = NULL;
 443
 444    /*
 445    printf("FINISH RENDER TO TEXTURE surf=%p\n", strb->surface);
 446    */
 447
 448    /* restore previous framebuffer state */
 449    st_invalidate_state(ctx, _NEW_BUFFERS);
 450 }
 451
 452
 453 /**
 454  * Validate a renderbuffer attachment for a particular set of bindings.
 455  */
 456 static GLboolean
 457 st_validate_attachment(struct gl_context *ctx,
 458                        struct pipe_screen *screen,
 459                        const struct gl_renderbuffer_attachment *att,
 460                        unsigned bindings)
 461 {
 462    const struct st_texture_object *stObj = st_texture_object(att->Texture);
 463    enum pipe_format format;
 464    gl_format texFormat;
 465
 466    /* Only validate texture attachments for now, since
 467     * st_renderbuffer_alloc_storage makes sure that
 468     * the format is supported.
 469     */
 470    if (att->Type != GL_TEXTURE)
 471       return GL_TRUE;
 472
 473    if (!stObj)
 474       return GL_FALSE;
 475
 476    format = stObj->pt->format;
 477    texFormat =
 478       stObj->base.Image[att->CubeMapFace][att->TextureLevel]->TexFormat;
 479
 480    /* If the encoding is sRGB and sRGB rendering cannot be enabled,
 481     * check for linear format support instead.
 482     * Later when we create a surface, we change the format to a linear one. */
 483    if (!ctx->Const.sRGBCapable &&
 484        _mesa_get_format_color_encoding(texFormat) == GL_SRGB) {
 485       const gl_format linearFormat = _mesa_get_srgb_format_linear(texFormat);
 486       format = st_mesa_format_to_pipe_format(linearFormat);
 487    }
 488
 489    return screen->is_format_supported(screen, format,
 490                                       PIPE_TEXTURE_2D,
 491                                       stObj->pt->nr_samples, bindings, 0);
 492 }
 493
 494
 495 /**
 496  * Check if two renderbuffer attachments name a combined depth/stencil
 497  * renderbuffer.
 498  */
 499 GLboolean
 500 st_is_depth_stencil_combined(const struct gl_renderbuffer_attachment *depth,
 501                              const struct gl_renderbuffer_attachment *stencil)
 502 {
 503    assert(depth && stencil);
 504
 505    if (depth->Type == stencil->Type) {
 506       if (depth->Type == GL_RENDERBUFFER_EXT &&
 507           depth->Renderbuffer == stencil->Renderbuffer)
 508          return GL_TRUE;
 509
 510       if (depth->Type == GL_TEXTURE &&
 511           depth->Texture == stencil->Texture)
 512          return GL_TRUE;
 513    }
 514
 515    return GL_FALSE;
 516 }
 517
 518
 519 /**
 520  * Check that the framebuffer configuration is valid in terms of what
 521  * the driver can support.
 522  *
 523  * For Gallium we only supports combined Z+stencil, not separate buffers.
 524  */
 525 static void
 526 st_validate_framebuffer(struct gl_context *ctx, struct gl_framebuffer *fb)
 527 {
 528    struct st_context *st = st_context(ctx);
 529    struct pipe_screen *screen = st->pipe->screen;
 530    const struct gl_renderbuffer_attachment *depth =
 531          &fb->Attachment[BUFFER_DEPTH];
 532    const struct gl_renderbuffer_attachment *stencil =
 533          &fb->Attachment[BUFFER_STENCIL];
 534    GLuint i;
 535
 536    if (depth->Type && stencil->Type && depth->Type != stencil->Type) {
 537       fb->_Status = GL_FRAMEBUFFER_UNSUPPORTED_EXT;
 538       return;
 539    }
 540    if (depth->Type == GL_RENDERBUFFER_EXT &&
 541        stencil->Type == GL_RENDERBUFFER_EXT &&
 542        depth->Renderbuffer != stencil->Renderbuffer) {
 543       fb->_Status = GL_FRAMEBUFFER_UNSUPPORTED_EXT;
 544       return;
 545    }
 546    if (depth->Type == GL_TEXTURE &&
 547        stencil->Type == GL_TEXTURE &&
 548        depth->Texture != stencil->Texture) {
 549       fb->_Status = GL_FRAMEBUFFER_UNSUPPORTED_EXT;
 550       return;
 551    }
 552
 553    if (!st_validate_attachment(ctx,
 554                                screen,
 555                                depth,
 556                                PIPE_BIND_DEPTH_STENCIL)) {
 557       fb->_Status = GL_FRAMEBUFFER_UNSUPPORTED_EXT;
 558       return;
 559    }
 560    if (!st_validate_attachment(ctx,
 561                                screen,
 562                                stencil,
 563                                PIPE_BIND_DEPTH_STENCIL)) {
 564       fb->_Status = GL_FRAMEBUFFER_UNSUPPORTED_EXT;
 565       return;
 566    }
 567    for (i = 0; i < ctx->Const.MaxColorAttachments; i++) {
 568       if (!st_validate_attachment(ctx,
 569                                   screen,
 570                                   &fb->Attachment[BUFFER_COLOR0 + i],
 571                                   PIPE_BIND_RENDER_TARGET)) {
 572          fb->_Status = GL_FRAMEBUFFER_UNSUPPORTED_EXT;
 573          return;
 574       }
 575    }
 576 }
 577
 578
 579 /**
 580  * Called via glDrawBuffer.
 581  */
 582 static void
 583 st_DrawBuffers(struct gl_context *ctx, GLsizei count, const GLenum *buffers)
 584 {
 585    struct st_context *st = st_context(ctx);
 586    struct gl_framebuffer *fb = ctx->DrawBuffer;
 587    GLuint i;
 588
 589    (void) count;
 590    (void) buffers;
 591
 592    /* add the renderbuffers on demand */
 593    for (i = 0; i < fb->_NumColorDrawBuffers; i++) {
 594       gl_buffer_index idx = fb->_ColorDrawBufferIndexes[i];
 595       st_manager_add_color_renderbuffer(st, fb, idx);
 596    }
 597 }
 598
 599
 600 /**
 601  * Called via glReadBuffer.
 602  */
 603 static void
 604 st_ReadBuffer(struct gl_context *ctx, GLenum buffer)
 605 {
 606    struct st_context *st = st_context(ctx);
 607    struct gl_framebuffer *fb = ctx->ReadBuffer;
 608
 609    (void) buffer;
 610
 611    /* add the renderbuffer on demand */
 612    st_manager_add_color_renderbuffer(st, fb, fb->_ColorReadBufferIndex);
 613 }
 614
 615
 616 void st_init_fbo_functions(struct dd_function_table *functions)
 617 {
 618 #if FEATURE_EXT_framebuffer_object
 619    functions->NewFramebuffer = st_new_framebuffer;
 620    functions->NewRenderbuffer = st_new_renderbuffer;
 621    functions->BindFramebuffer = st_bind_framebuffer;
 622    functions->FramebufferRenderbuffer = st_framebuffer_renderbuffer;
 623    functions->RenderTexture = st_render_texture;
 624    functions->FinishRenderTexture = st_finish_render_texture;
 625    functions->ValidateFramebuffer = st_validate_framebuffer;
 626 #endif
 627    /* no longer needed by core Mesa, drivers handle resizes...
 628    functions->ResizeBuffers = st_resize_buffers;
 629    */
 630
 631    functions->DrawBuffers = st_DrawBuffers;
 632    functions->ReadBuffer = st_ReadBuffer;
 633 }
 634
 635 /* XXX unused ? */
 636 struct pipe_sampler_view *
 637 st_get_renderbuffer_sampler_view(struct st_renderbuffer *rb,
 638                                  struct pipe_context *pipe)
 639 {
 640    if (!rb->sampler_view) {
 641       rb->sampler_view = st_create_texture_sampler_view(pipe, rb->texture);
 642    }
 643
 644    return rb->sampler_view;
 645 }