src/mesa/main/framebuffer.c

   1 /*
   2  * Mesa 3-D graphics library
   3  * Version:  6.5.1
   4  *
   5  * Copyright (C) 1999-2006  Brian Paul   All Rights Reserved.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a
   8  * copy of this software and associated documentation files (the "Software"),
   9  * to deal in the Software without restriction, including without limitation
  10  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  11  * and/or sell copies of the Software, and to permit persons to whom the
  12  * Software is furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included
  15  * in all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  18  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  20  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  21  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  22  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  23  */
  24
  25
  26 /**
  27  * Functions for allocating/managing framebuffers and renderbuffers.
  28  * Also, routines for reading/writing renderbuffer data as ubytes,
  29  * ushorts, uints, etc.
  30  */
  31
  32
  33 #include "glheader.h"
  34 #include "imports.h"
  35 #include "context.h"
  36 #include "depthstencil.h"
  37 #include "mtypes.h"
  38 #include "fbobject.h"
  39 #include "framebuffer.h"
  40 #include "renderbuffer.h"
  41
  42
  43
  44 /**
  45  * Compute/set the _DepthMax field for the given framebuffer.
  46  * This value depends on the Z buffer resolution.
  47  */
  48 static void
  49 compute_depth_max(struct gl_framebuffer *fb)
  50 {
  51    if (fb->Visual.depthBits == 0) {
  52       /* Special case.  Even if we don't have a depth buffer we need
  53        * good values for DepthMax for Z vertex transformation purposes
  54        * and for per-fragment fog computation.
  55        */
  56       fb->_DepthMax = (1 << 16) - 1;
  57    }
  58    else if (fb->Visual.depthBits < 32) {
  59       fb->_DepthMax = (1 << fb->Visual.depthBits) - 1;
  60    }
  61    else {
  62       /* Special case since shift values greater than or equal to the
  63        * number of bits in the left hand expression's type are undefined.
  64        */
  65       fb->_DepthMax = 0xffffffff;
  66    }
  67    fb->_DepthMaxF = (GLfloat) fb->_DepthMax;
  68    fb->_MRD = 1.0;  /* Minimum resolvable depth value, for polygon offset */
  69 }
  70
  71
  72 /**
  73  * Set the framebuffer's _DepthBuffer field, taking care of
  74  * reference counts, etc.
  75  */
  76 static void
  77 set_depth_renderbuffer(struct gl_framebuffer *fb,
  78                        struct gl_renderbuffer *rb)
  79 {
  80    if (fb->_DepthBuffer) {
  81       _mesa_dereference_renderbuffer(&fb->_DepthBuffer);
  82    }
  83    fb->_DepthBuffer = rb;
  84    if (rb) {
  85       rb->RefCount++;
  86    }
  87 }
  88
  89
  90 /**
  91  * Set the framebuffer's _StencilBuffer field, taking care of
  92  * reference counts, etc.
  93  */
  94 static void
  95 set_stencil_renderbuffer(struct gl_framebuffer *fb,
  96                          struct gl_renderbuffer *rb)
  97 {
  98    if (fb->_StencilBuffer) {
  99       _mesa_dereference_renderbuffer(&fb->_StencilBuffer);
 100    }
 101    fb->_StencilBuffer = rb;
 102    if (rb) {
 103       rb->RefCount++;
 104    }
 105 }
 106
 107
 108 /**
 109  * Create and initialize a gl_framebuffer object.
 110  * This is intended for creating _window_system_ framebuffers, not generic
 111  * framebuffer objects ala GL_EXT_framebuffer_object.
 112  *
 113  * \sa _mesa_new_framebuffer
 114  */
 115 struct gl_framebuffer *
 116 _mesa_create_framebuffer(const GLvisual *visual)
 117 {
 118    struct gl_framebuffer *fb = CALLOC_STRUCT(gl_framebuffer);
 119    assert(visual);
 120    if (fb) {
 121       _mesa_initialize_framebuffer(fb, visual);
 122    }
 123    return fb;
 124 }
 125
 126
 127 /**
 128  * Allocate a new gl_framebuffer object.
 129  * This is the default function for ctx->Driver.NewFramebuffer().
 130  * This is for allocating user-created framebuffers, not window-system
 131  * framebuffers!
 132  * \sa _mesa_create_framebuffer
 133  */
 134 struct gl_framebuffer *
 135 _mesa_new_framebuffer(GLcontext *ctx, GLuint name)
 136 {
 137    struct gl_framebuffer *fb;
 138    (void) ctx;
 139    assert(name != 0);
 140    fb = CALLOC_STRUCT(gl_framebuffer);
 141    if (fb) {
 142       fb->Name = name;
 143       fb->RefCount = 1;
 144       fb->ColorDrawBuffer[0] = GL_COLOR_ATTACHMENT0_EXT;
 145       fb->_ColorDrawBufferMask[0] = BUFFER_BIT_COLOR0;
 146       fb->ColorReadBuffer = GL_COLOR_ATTACHMENT0_EXT;
 147       fb->_ColorReadBufferIndex = BUFFER_COLOR0;
 148       fb->Delete = _mesa_destroy_framebuffer;
 149    }
 150    return fb;
 151 }
 152
 153
 154 /**
 155  * Initialize a gl_framebuffer object.  Typically used to initialize
 156  * window system-created framebuffers, not user-created framebuffers.
 157  * \sa _mesa_create_framebuffer
 158  */
 159 void
 160 _mesa_initialize_framebuffer(struct gl_framebuffer *fb, const GLvisual *visual)
 161 {
 162    assert(fb);
 163    assert(visual);
 164
 165    _mesa_bzero(fb, sizeof(struct gl_framebuffer));
 166
 167    _glthread_INIT_MUTEX(fb->Mutex);
 168
 169    /* save the visual */
 170    fb->Visual = *visual;
 171
 172    /* Init glRead/DrawBuffer state */
 173    if (visual->doubleBufferMode) {
 174       fb->ColorDrawBuffer[0] = GL_BACK;
 175       fb->_ColorDrawBufferMask[0] = BUFFER_BIT_BACK_LEFT;
 176       fb->ColorReadBuffer = GL_BACK;
 177       fb->_ColorReadBufferIndex = BUFFER_BACK_LEFT;
 178    }
 179    else {
 180       fb->ColorDrawBuffer[0] = GL_FRONT;
 181       fb->_ColorDrawBufferMask[0] = BUFFER_BIT_FRONT_LEFT;
 182       fb->ColorReadBuffer = GL_FRONT;
 183       fb->_ColorReadBufferIndex = BUFFER_FRONT_LEFT;
 184    }
 185
 186    fb->Delete = _mesa_destroy_framebuffer;
 187    fb->_Status = GL_FRAMEBUFFER_COMPLETE_EXT;
 188
 189    compute_depth_max(fb);
 190 }
 191
 192
 193 /**
 194  * Deallocate buffer and everything attached to it.
 195  * Typically called via the gl_framebuffer->Delete() method.
 196  */
 197 void
 198 _mesa_destroy_framebuffer(struct gl_framebuffer *fb)
 199 {
 200    if (fb) {
 201       _glthread_DESTROY_MUTEX(fb->Mutex);
 202       _mesa_free_framebuffer_data(fb);
 203       _mesa_free(fb);
 204    }
 205 }
 206
 207
 208 /**
 209  * Free all the data hanging off the given gl_framebuffer, but don't free
 210  * the gl_framebuffer object itself.
 211  */
 212 void
 213 _mesa_free_framebuffer_data(struct gl_framebuffer *fb)
 214 {
 215    GLuint i;
 216
 217    assert(fb);
 218
 219    for (i = 0; i < BUFFER_COUNT; i++) {
 220       struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
 221       if (att->Renderbuffer) {
 222          struct gl_renderbuffer *rb = att->Renderbuffer;
 223          /* remove framebuffer's reference to renderbuffer */
 224          _mesa_dereference_renderbuffer(&rb);
 225          if (rb && rb->Name == 0) {
 226             /* delete window system renderbuffer */
 227             _mesa_dereference_renderbuffer(&rb);
 228          }
 229       }
 230       att->Type = GL_NONE;
 231       att->Renderbuffer = NULL;
 232    }
 233
 234    /* unbind depth/stencil to decr ref counts */
 235    set_depth_renderbuffer(fb, NULL);
 236    set_stencil_renderbuffer(fb, NULL);
 237 }
 238
 239
 240 /**
 241  * Decrement the reference count on a framebuffer and delete it when
 242  * the refcount hits zero.
 243  * Note: we pass the address of a pointer and set it to NULL if we delete it.
 244  */
 245 void
 246 _mesa_dereference_framebuffer(struct gl_framebuffer **fb)
 247 {
 248    GLboolean deleteFlag = GL_FALSE;
 249
 250    _glthread_LOCK_MUTEX((*fb)->Mutex);
 251    {
 252       ASSERT((*fb)->RefCount > 0);
 253       (*fb)->RefCount--;
 254       deleteFlag = ((*fb)->RefCount == 0);
 255    }
 256    _glthread_UNLOCK_MUTEX((*fb)->Mutex);
 257
 258    if (deleteFlag) {
 259       (*fb)->Delete(*fb);
 260       *fb = NULL;
 261    }
 262 }
 263
 264
 265
 266
 267 /**
 268  * Resize the given framebuffer's renderbuffers to the new width and height.
 269  * This should only be used for window-system framebuffers, not
 270  * user-created renderbuffers (i.e. made with GL_EXT_framebuffer_object).
 271  * This will typically be called via ctx->Driver.ResizeBuffers() or directly
 272  * from a device driver.
 273  *
 274  * \note it's possible for ctx to be null since a window can be resized
 275  * without a currently bound rendering context.
 276  */
 277 void
 278 _mesa_resize_framebuffer(GLcontext *ctx, struct gl_framebuffer *fb,
 279                          GLuint width, GLuint height)
 280 {
 281    GLuint i;
 282
 283    /* XXX I think we could check if the size is not changing
 284     * and return early.
 285     */
 286
 287    /* For window system framebuffers, Name is zero */
 288    assert(fb->Name == 0);
 289
 290    for (i = 0; i < BUFFER_COUNT; i++) {
 291       struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
 292       if (att->Type == GL_RENDERBUFFER_EXT && att->Renderbuffer) {
 293          struct gl_renderbuffer *rb = att->Renderbuffer;
 294          /* only resize if size is changing */
 295          if (rb->Width != width || rb->Height != height) {
 296             /* could just as well pass rb->_ActualFormat here */
 297             if (rb->AllocStorage(ctx, rb, rb->InternalFormat, width, height)) {
 298                ASSERT(rb->Width == width);
 299                ASSERT(rb->Height == height);
 300             }
 301             else {
 302                _mesa_error(ctx, GL_OUT_OF_MEMORY, "Resizing framebuffer");
 303                /* no return */
 304             }
 305          }
 306       }
 307    }
 308
 309    if (fb->_DepthBuffer) {
 310       struct gl_renderbuffer *rb = fb->_DepthBuffer;
 311       if (rb->Width != width || rb->Height != height) {
 312          if (!rb->AllocStorage(ctx, rb, rb->InternalFormat, width, height)) {
 313             _mesa_error(ctx, GL_OUT_OF_MEMORY, "Resizing framebuffer");
 314          }
 315       }
 316    }
 317
 318    if (fb->_StencilBuffer) {
 319       struct gl_renderbuffer *rb = fb->_StencilBuffer;
 320       if (rb->Width != width || rb->Height != height) {
 321          if (!rb->AllocStorage(ctx, rb, rb->InternalFormat, width, height)) {
 322             _mesa_error(ctx, GL_OUT_OF_MEMORY, "Resizing framebuffer");
 323          }
 324       }
 325    }
 326
 327    fb->Width = width;
 328    fb->Height = height;
 329
 330    if (ctx) {
 331       /* update scissor / window bounds */
 332       _mesa_update_draw_buffer_bounds(ctx);
 333       /* Signal new buffer state so that swrast will update its clipping
 334        * info (the CLIP_BIT flag).
 335        */
 336       ctx->NewState |= _NEW_BUFFERS;
 337    }
 338 }
 339
 340
 341 /**
 342  * Examine all the framebuffer's renderbuffers to update the Width/Height
 343  * fields of the framebuffer.  If we have renderbuffers with different
 344  * sizes, set the framebuffer's width and height to zero.
 345  * Note: this is only intended for user-created framebuffers, not
 346  * window-system framebuffes.
 347  */
 348 static void
 349 update_framebuffer_size(struct gl_framebuffer *fb)
 350 {
 351    GLboolean haveSize = GL_FALSE;
 352    GLuint i;
 353
 354    /* user-created framebuffers only */
 355    assert(fb->Name);
 356
 357    for (i = 0; i < BUFFER_COUNT; i++) {
 358       struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
 359       const struct gl_renderbuffer *rb = att->Renderbuffer;
 360       if (rb) {
 361          if (haveSize) {
 362             if (rb->Width != fb->Width && rb->Height != fb->Height) {
 363                /* size mismatch! */
 364                fb->Width = 0;
 365                fb->Height = 0;
 366                return;
 367             }
 368          }
 369          else {
 370             fb->Width = rb->Width;
 371             fb->Height = rb->Height;
 372             haveSize = GL_TRUE;
 373          }
 374       }
 375    }
 376 }
 377
 378
 379 /**
 380  * Update the context's current drawing buffer's Xmin, Xmax, Ymin, Ymax fields.
 381  * These values are computed from the buffer's width and height and
 382  * the scissor box, if it's enabled.
 383  * \param ctx  the GL context.
 384  */
 385 void
 386 _mesa_update_draw_buffer_bounds(GLcontext *ctx)
 387 {
 388    struct gl_framebuffer *buffer = ctx->DrawBuffer;
 389
 390    if (!buffer)
 391       return;
 392
 393    if (buffer->Name) {
 394       /* user-created framebuffer size depends on the renderbuffers */
 395       update_framebuffer_size(buffer);
 396    }
 397
 398    buffer->_Xmin = 0;
 399    buffer->_Ymin = 0;
 400    buffer->_Xmax = buffer->Width;
 401    buffer->_Ymax = buffer->Height;
 402
 403    if (ctx->Scissor.Enabled) {
 404       if (ctx->Scissor.X > buffer->_Xmin) {
 405          buffer->_Xmin = ctx->Scissor.X;
 406       }
 407       if (ctx->Scissor.Y > buffer->_Ymin) {
 408          buffer->_Ymin = ctx->Scissor.Y;
 409       }
 410       if (ctx->Scissor.X + ctx->Scissor.Width < buffer->_Xmax) {
 411          buffer->_Xmax = ctx->Scissor.X + ctx->Scissor.Width;
 412       }
 413       if (ctx->Scissor.Y + ctx->Scissor.Height < buffer->_Ymax) {
 414          buffer->_Ymax = ctx->Scissor.Y + ctx->Scissor.Height;
 415       }
 416       /* finally, check for empty region */
 417       if (buffer->_Xmin > buffer->_Xmax) {
 418          buffer->_Xmin = buffer->_Xmax;
 419       }
 420       if (buffer->_Ymin > buffer->_Ymax) {
 421          buffer->_Ymin = buffer->_Ymax;
 422       }
 423    }
 424
 425    ASSERT(buffer->_Xmin <= buffer->_Xmax);
 426    ASSERT(buffer->_Ymin <= buffer->_Ymax);
 427 }
 428
 429
 430 /**
 431  * The glGet queries of the framebuffer red/green/blue size, stencil size,
 432  * etc. are satisfied by the fields of ctx->DrawBuffer->Visual.  These can
 433  * change depending on the renderbuffer bindings.  This function updates
 434  * the given framebuffer's Visual from the current renderbuffer bindings.
 435  *
 436  * This may apply to user-created framebuffers or window system framebuffers.
 437  *
 438  * Also note: ctx->DrawBuffer->Visual.depthBits might not equal
 439  * ctx->DrawBuffer->Attachment[BUFFER_DEPTH].Renderbuffer.DepthBits.
 440  * The former one is used to convert floating point depth values into
 441  * integer Z values.
 442  */
 443 void
 444 _mesa_update_framebuffer_visual(struct gl_framebuffer *fb)
 445 {
 446    GLuint i;
 447
 448    _mesa_bzero(&fb->Visual, sizeof(fb->Visual));
 449    fb->Visual.rgbMode = GL_TRUE; /* assume this */
 450
 451 #if 0 /* this _might_ be needed */
 452    if (fb->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
 453       /* leave visual fields zero'd */
 454       return;
 455    }
 456 #endif
 457
 458    /* find first RGB or CI renderbuffer */
 459    for (i = 0; i < BUFFER_COUNT; i++) {
 460       if (fb->Attachment[i].Renderbuffer) {
 461          const struct gl_renderbuffer *rb = fb->Attachment[i].Renderbuffer;
 462          if (rb->_BaseFormat == GL_RGBA || rb->_BaseFormat == GL_RGB) {
 463             fb->Visual.redBits = rb->RedBits;
 464             fb->Visual.greenBits = rb->GreenBits;
 465             fb->Visual.blueBits = rb->BlueBits;
 466             fb->Visual.alphaBits = rb->AlphaBits;
 467             fb->Visual.rgbBits = fb->Visual.redBits
 468                + fb->Visual.greenBits + fb->Visual.blueBits;
 469             fb->Visual.floatMode = GL_FALSE;
 470             break;
 471          }
 472          else if (rb->_BaseFormat == GL_COLOR_INDEX) {
 473             fb->Visual.indexBits = rb->IndexBits;
 474             fb->Visual.rgbMode = GL_FALSE;
 475             break;
 476          }
 477       }
 478    }
 479
 480    if (fb->Attachment[BUFFER_DEPTH].Renderbuffer) {
 481       fb->Visual.haveDepthBuffer = GL_TRUE;
 482       fb->Visual.depthBits
 483          = fb->Attachment[BUFFER_DEPTH].Renderbuffer->DepthBits;
 484    }
 485
 486    if (fb->Attachment[BUFFER_STENCIL].Renderbuffer) {
 487       fb->Visual.haveStencilBuffer = GL_TRUE;
 488       fb->Visual.stencilBits
 489          = fb->Attachment[BUFFER_STENCIL].Renderbuffer->StencilBits;
 490    }
 491
 492    if (fb->Attachment[BUFFER_ACCUM].Renderbuffer) {
 493       fb->Visual.haveAccumBuffer = GL_TRUE;
 494       fb->Visual.accumRedBits
 495          = fb->Attachment[BUFFER_DEPTH].Renderbuffer->RedBits;
 496       fb->Visual.accumGreenBits
 497          = fb->Attachment[BUFFER_DEPTH].Renderbuffer->GreenBits;
 498       fb->Visual.accumBlueBits
 499          = fb->Attachment[BUFFER_DEPTH].Renderbuffer->BlueBits;
 500       fb->Visual.accumAlphaBits
 501          = fb->Attachment[BUFFER_DEPTH].Renderbuffer->AlphaBits;
 502    }
 503
 504    compute_depth_max(fb);
 505 }
 506
 507
 508 /**
 509  * Update the framebuffer's _DepthBuffer field using the renderbuffer
 510  * found at the given attachment index.
 511  *
 512  * If that attachment points to a combined GL_DEPTH_STENCIL renderbuffer,
 513  * create and install a depth wrapper/adaptor.
 514  *
 515  * \param fb  the framebuffer whose _DepthBuffer field to update
 516  * \param attIndex  indicates the renderbuffer to possibly wrap
 517  */
 518 void
 519 _mesa_update_depth_buffer(GLcontext *ctx,
 520                           struct gl_framebuffer *fb,
 521                           GLuint attIndex)
 522 {
 523    struct gl_renderbuffer *depthRb;
 524
 525    /* only one possiblity for now */
 526    ASSERT(attIndex == BUFFER_DEPTH);
 527
 528    depthRb = fb->Attachment[attIndex].Renderbuffer;
 529
 530    if (depthRb && depthRb->_ActualFormat == GL_DEPTH24_STENCIL8_EXT) {
 531       /* The attached depth buffer is a GL_DEPTH_STENCIL renderbuffer */
 532       if (!fb->_DepthBuffer
 533           || fb->_DepthBuffer->Wrapped != depthRb
 534           || fb->_DepthBuffer->_BaseFormat != GL_DEPTH_COMPONENT) {
 535          /* need to update wrapper */
 536          struct gl_renderbuffer *wrapper
 537             = _mesa_new_z24_renderbuffer_wrapper(ctx, depthRb);
 538          set_depth_renderbuffer(fb, wrapper);
 539          ASSERT(fb->_DepthBuffer->Wrapped == depthRb);
 540       }
 541    }
 542    else {
 543       /* depthRb may be null */
 544       set_depth_renderbuffer(fb, depthRb);
 545    }
 546 }
 547
 548
 549 /**
 550  * Update the framebuffer's _StencilBuffer field using the renderbuffer
 551  * found at the given attachment index.
 552  *
 553  * If that attachment points to a combined GL_DEPTH_STENCIL renderbuffer,
 554  * create and install a stencil wrapper/adaptor.
 555  *
 556  * \param fb  the framebuffer whose _StencilBuffer field to update
 557  * \param attIndex  indicates the renderbuffer to possibly wrap
 558  */
 559 void
 560 _mesa_update_stencil_buffer(GLcontext *ctx,
 561                             struct gl_framebuffer *fb,
 562                             GLuint attIndex)
 563 {
 564    struct gl_renderbuffer *stencilRb;
 565
 566    ASSERT(attIndex == BUFFER_DEPTH ||
 567           attIndex == BUFFER_STENCIL);
 568
 569    stencilRb = fb->Attachment[attIndex].Renderbuffer;
 570
 571    if (stencilRb && stencilRb->_ActualFormat == GL_DEPTH24_STENCIL8_EXT) {
 572       /* The attached stencil buffer is a GL_DEPTH_STENCIL renderbuffer */
 573       if (!fb->_StencilBuffer
 574           || fb->_StencilBuffer->Wrapped != stencilRb
 575           || fb->_StencilBuffer->_BaseFormat != GL_STENCIL_INDEX) {
 576          /* need to update wrapper */
 577          struct gl_renderbuffer *wrapper
 578             = _mesa_new_s8_renderbuffer_wrapper(ctx, stencilRb);
 579          set_stencil_renderbuffer(fb, wrapper);
 580          ASSERT(fb->_StencilBuffer->Wrapped == stencilRb);
 581       }
 582    }
 583    else {
 584       /* stencilRb may be null */
 585       set_stencil_renderbuffer(fb, stencilRb);
 586    }
 587 }
 588
 589
 590 /**
 591  * Update the list of color drawing renderbuffer pointers.
 592  * Later, when we're rendering we'll loop from 0 to _NumColorDrawBuffers
 593  * writing colors.
 594  */
 595 static void
 596 update_color_draw_buffers(GLcontext *ctx, struct gl_framebuffer *fb)
 597 {
 598    GLuint output;
 599
 600    /*
 601     * Fragment programs can write to multiple colorbuffers with
 602     * the GL_ARB_draw_buffers extension.
 603     */
 604    for (output = 0; output < ctx->Const.MaxDrawBuffers; output++) {
 605       GLbitfield bufferMask = fb->_ColorDrawBufferMask[output];
 606       GLuint count = 0;
 607       GLuint i;
 608       /* We need the inner loop here because glDrawBuffer(GL_FRONT_AND_BACK)
 609        * can specify writing to two or four color buffers (for example).
 610        */
 611       for (i = 0; bufferMask && i < BUFFER_COUNT; i++) {
 612          const GLuint bufferBit = 1 << i;
 613          if (bufferBit & bufferMask) {
 614             struct gl_renderbuffer *rb = fb->Attachment[i].Renderbuffer;
 615             if (rb) {
 616                fb->_ColorDrawBuffers[output][count] = rb;
 617                count++;
 618             }
 619             else {
 620                /*_mesa_warning(ctx, "DrawBuffer names a missing buffer!\n");*/
 621             }
 622             bufferMask &= ~bufferBit;
 623          }
 624       }
 625       fb->_NumColorDrawBuffers[output] = count;
 626    }
 627 }
 628
 629
 630 /**
 631  * Update the color read renderbuffer pointer.
 632  * Unlike the DrawBuffer, we can only read from one (or zero) color buffers.
 633  */
 634 static void
 635 update_color_read_buffer(GLcontext *ctx, struct gl_framebuffer *fb)
 636 {
 637    (void) ctx;
 638    if (fb->_ColorReadBufferIndex == -1) {
 639       fb->_ColorReadBuffer = NULL; /* legal! */
 640    }
 641    else {
 642       ASSERT(fb->_ColorReadBufferIndex >= 0);
 643       ASSERT(fb->_ColorReadBufferIndex < BUFFER_COUNT);
 644       fb->_ColorReadBuffer
 645          = fb->Attachment[fb->_ColorReadBufferIndex].Renderbuffer;
 646    }
 647 }
 648
 649
 650 /**
 651  * Update state related to the current draw/read framebuffers.
 652  * Specifically, update these framebuffer fields:
 653  *    _ColorDrawBuffers
 654  *    _NumColorDrawBuffers
 655  *    _ColorReadBuffer
 656  *    _DepthBuffer
 657  *    _StencilBuffer
 658  * If the current framebuffer is user-created, make sure it's complete.
 659  * The following functions can effect this state:  glReadBuffer,
 660  * glDrawBuffer, glDrawBuffersARB, glFramebufferRenderbufferEXT,
 661  * glRenderbufferStorageEXT.
 662  */
 663 void
 664 _mesa_update_framebuffer(GLcontext *ctx)
 665 {
 666    struct gl_framebuffer *fb = ctx->DrawBuffer;
 667
 668    /* Completeness only matters for user-created framebuffers */
 669    if (fb->Name != 0) {
 670       _mesa_test_framebuffer_completeness(ctx, fb);
 671       _mesa_update_framebuffer_visual(fb);
 672    }
 673
 674    update_color_draw_buffers(ctx, fb);
 675    update_color_read_buffer(ctx, fb);
 676    _mesa_update_depth_buffer(ctx, fb, BUFFER_DEPTH);
 677    _mesa_update_stencil_buffer(ctx, fb, BUFFER_STENCIL);
 678
 679    compute_depth_max(fb);
 680 }
 681
 682
 683 /**
 684  * Check if the renderbuffer for a read operation (glReadPixels, glCopyPixels,
 685  * glCopyTex[Sub]Image, etc. exists.
 686  * \param format  a basic image format such as GL_RGB, GL_RGBA, GL_ALPHA,
 687  *                GL_DEPTH_COMPONENT, etc. or GL_COLOR, GL_DEPTH, GL_STENCIL.
 688  * \return GL_TRUE if buffer exists, GL_FALSE otherwise
 689  */
 690 GLboolean
 691 _mesa_source_buffer_exists(GLcontext *ctx, GLenum format)
 692 {
 693    const struct gl_renderbuffer_attachment *att
 694       = ctx->ReadBuffer->Attachment;
 695
 696    if (ctx->ReadBuffer->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
 697       return GL_FALSE;
 698    }
 699
 700    switch (format) {
 701    case GL_COLOR:
 702    case GL_RED:
 703    case GL_GREEN:
 704    case GL_BLUE:
 705    case GL_ALPHA:
 706    case GL_LUMINANCE:
 707    case GL_LUMINANCE_ALPHA:
 708    case GL_INTENSITY:
 709    case GL_RGB:
 710    case GL_BGR:
 711    case GL_RGBA:
 712    case GL_BGRA:
 713    case GL_ABGR_EXT:
 714    case GL_COLOR_INDEX:
 715       if (ctx->ReadBuffer->_ColorReadBuffer == NULL) {
 716          return GL_FALSE;
 717       }
 718       /* XXX enable this post 6.5 release:
 719       ASSERT(ctx->ReadBuffer->_ColorReadBuffer->RedBits > 0 ||
 720              ctx->ReadBuffer->_ColorReadBuffer->IndexBits > 0);
 721       */
 722       break;
 723    case GL_DEPTH:
 724    case GL_DEPTH_COMPONENT:
 725       if (!att[BUFFER_DEPTH].Renderbuffer) {
 726          return GL_FALSE;
 727       }
 728       ASSERT(att[BUFFER_DEPTH].Renderbuffer->DepthBits > 0);
 729       break;
 730    case GL_STENCIL:
 731    case GL_STENCIL_INDEX:
 732       if (!att[BUFFER_STENCIL].Renderbuffer) {
 733          return GL_FALSE;
 734       }
 735       ASSERT(att[BUFFER_STENCIL].Renderbuffer->StencilBits > 0);
 736       break;
 737    case GL_DEPTH_STENCIL_EXT:
 738       if (!att[BUFFER_DEPTH].Renderbuffer ||
 739           !att[BUFFER_STENCIL].Renderbuffer) {
 740          return GL_FALSE;
 741       }
 742       ASSERT(att[BUFFER_DEPTH].Renderbuffer->DepthBits > 0);
 743       ASSERT(att[BUFFER_STENCIL].Renderbuffer->StencilBits > 0);
 744       break;
 745    default:
 746       _mesa_problem(ctx,
 747                     "Unexpected format 0x%x in _mesa_source_buffer_exists",
 748                     format);
 749       return GL_FALSE;
 750    }
 751
 752    /* OK */
 753    return GL_TRUE;
 754 }
 755
 756
 757 /**
 758  * As above, but for drawing operations.
 759  * XXX code do some code merging w/ above function.
 760  */
 761 GLboolean
 762 _mesa_dest_buffer_exists(GLcontext *ctx, GLenum format)
 763 {
 764    const struct gl_renderbuffer_attachment *att
 765       = ctx->ReadBuffer->Attachment;
 766
 767    if (ctx->DrawBuffer->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
 768       return GL_FALSE;
 769    }
 770
 771    switch (format) {
 772    case GL_COLOR:
 773    case GL_RED:
 774    case GL_GREEN:
 775    case GL_BLUE:
 776    case GL_ALPHA:
 777    case GL_LUMINANCE:
 778    case GL_LUMINANCE_ALPHA:
 779    case GL_INTENSITY:
 780    case GL_RGB:
 781    case GL_BGR:
 782    case GL_RGBA:
 783    case GL_BGRA:
 784    case GL_ABGR_EXT:
 785    case GL_COLOR_INDEX:
 786       /* nothing special */
 787       /* Could assert that colorbuffer has RedBits > 0 */
 788       break;
 789    case GL_DEPTH:
 790    case GL_DEPTH_COMPONENT:
 791       if (!att[BUFFER_DEPTH].Renderbuffer) {
 792          return GL_FALSE;
 793       }
 794       ASSERT(att[BUFFER_DEPTH].Renderbuffer->DepthBits > 0);
 795       break;
 796    case GL_STENCIL:
 797    case GL_STENCIL_INDEX:
 798       if (!att[BUFFER_STENCIL].Renderbuffer) {
 799          return GL_FALSE;
 800       }
 801       ASSERT(att[BUFFER_STENCIL].Renderbuffer->StencilBits > 0);
 802       break;
 803    case GL_DEPTH_STENCIL_EXT:
 804       if (!att[BUFFER_DEPTH].Renderbuffer ||
 805           !att[BUFFER_STENCIL].Renderbuffer) {
 806          return GL_FALSE;
 807       }
 808       ASSERT(att[BUFFER_DEPTH].Renderbuffer->DepthBits > 0);
 809       ASSERT(att[BUFFER_STENCIL].Renderbuffer->StencilBits > 0);
 810       break;
 811    default:
 812       _mesa_problem(ctx,
 813                     "Unexpected format 0x%x in _mesa_source_buffer_exists",
 814                     format);
 815       return GL_FALSE;
 816    }
 817
 818    /* OK */
 819    return GL_TRUE;
 820 }