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_unreference_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_unreference_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    fb->RefCount = 1;
 170
 171    /* save the visual */
 172    fb->Visual = *visual;
 173
 174    /* Init glRead/DrawBuffer state */
 175    if (visual->doubleBufferMode) {
 176       fb->ColorDrawBuffer[0] = GL_BACK;
 177       fb->_ColorDrawBufferMask[0] = BUFFER_BIT_BACK_LEFT;
 178       fb->ColorReadBuffer = GL_BACK;
 179       fb->_ColorReadBufferIndex = BUFFER_BACK_LEFT;
 180    }
 181    else {
 182       fb->ColorDrawBuffer[0] = GL_FRONT;
 183       fb->_ColorDrawBufferMask[0] = BUFFER_BIT_FRONT_LEFT;
 184       fb->ColorReadBuffer = GL_FRONT;
 185       fb->_ColorReadBufferIndex = BUFFER_FRONT_LEFT;
 186    }
 187
 188    fb->Delete = _mesa_destroy_framebuffer;
 189    fb->_Status = GL_FRAMEBUFFER_COMPLETE_EXT;
 190
 191    compute_depth_max(fb);
 192 }
 193
 194
 195 /**
 196  * Deallocate buffer and everything attached to it.
 197  * Typically called via the gl_framebuffer->Delete() method.
 198  */
 199 void
 200 _mesa_destroy_framebuffer(struct gl_framebuffer *fb)
 201 {
 202    if (fb) {
 203       _mesa_free_framebuffer_data(fb);
 204       _mesa_free(fb);
 205    }
 206 }
 207
 208
 209 /**
 210  * Free all the data hanging off the given gl_framebuffer, but don't free
 211  * the gl_framebuffer object itself.
 212  */
 213 void
 214 _mesa_free_framebuffer_data(struct gl_framebuffer *fb)
 215 {
 216    GLuint i;
 217
 218    assert(fb);
 219    assert(fb->RefCount == 0);
 220
 221    _glthread_DESTROY_MUTEX(fb->Mutex);
 222
 223    for (i = 0; i < BUFFER_COUNT; i++) {
 224       struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
 225       if (att->Renderbuffer) {
 226          _mesa_unreference_renderbuffer(&att->Renderbuffer);
 227       }
 228       if (att->Texture) {
 229          /* render to texture */
 230          att->Texture->RefCount--;
 231          if (att->Texture->RefCount == 0) {
 232             GET_CURRENT_CONTEXT(ctx);
 233             if (ctx) {
 234                ctx->Driver.DeleteTexture(ctx, att->Texture);
 235             }
 236          }
 237       }
 238       att->Type = GL_NONE;
 239       att->Texture = NULL;
 240    }
 241
 242    /* unbind depth/stencil to decr ref counts */
 243    set_depth_renderbuffer(fb, NULL);
 244    set_stencil_renderbuffer(fb, NULL);
 245 }
 246
 247
 248 /**
 249  * Set *ptr to point to fb, with refcounting and locking.
 250  */
 251 void
 252 _mesa_reference_framebuffer(struct gl_framebuffer **ptr,
 253                             struct gl_framebuffer *fb)
 254 {
 255    assert(ptr);
 256    assert(!*ptr);
 257    assert(fb);
 258    _glthread_LOCK_MUTEX(fb->Mutex);
 259    fb->RefCount++;
 260    _glthread_UNLOCK_MUTEX(fb->Mutex);
 261    *ptr = fb;
 262 }
 263
 264
 265 /**
 266  * Undo/remove a reference to a framebuffer object.
 267  * Decrement the framebuffer object's reference count and delete it when
 268  * the refcount hits zero.
 269  * Note: we pass the address of a pointer and set it to NULL.
 270  */
 271 void
 272 _mesa_unreference_framebuffer(struct gl_framebuffer **fb)
 273 {
 274    assert(fb);
 275    if (*fb) {
 276       GLboolean deleteFlag = GL_FALSE;
 277
 278       _glthread_LOCK_MUTEX((*fb)->Mutex);
 279       ASSERT((*fb)->RefCount > 0);
 280       (*fb)->RefCount--;
 281       deleteFlag = ((*fb)->RefCount == 0);
 282       _glthread_UNLOCK_MUTEX((*fb)->Mutex);
 283
 284       if (deleteFlag)
 285          (*fb)->Delete(*fb);
 286
 287       *fb = NULL;
 288    }
 289 }
 290
 291
 292
 293
 294 /**
 295  * Resize the given framebuffer's renderbuffers to the new width and height.
 296  * This should only be used for window-system framebuffers, not
 297  * user-created renderbuffers (i.e. made with GL_EXT_framebuffer_object).
 298  * This will typically be called via ctx->Driver.ResizeBuffers() or directly
 299  * from a device driver.
 300  *
 301  * \note it's possible for ctx to be null since a window can be resized
 302  * without a currently bound rendering context.
 303  */
 304 void
 305 _mesa_resize_framebuffer(GLcontext *ctx, struct gl_framebuffer *fb,
 306                          GLuint width, GLuint height)
 307 {
 308    GLuint i;
 309
 310    /* XXX I think we could check if the size is not changing
 311     * and return early.
 312     */
 313
 314    /* For window system framebuffers, Name is zero */
 315    assert(fb->Name == 0);
 316
 317    for (i = 0; i < BUFFER_COUNT; i++) {
 318       struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
 319       if (att->Type == GL_RENDERBUFFER_EXT && att->Renderbuffer) {
 320          struct gl_renderbuffer *rb = att->Renderbuffer;
 321          /* only resize if size is changing */
 322          if (rb->Width != width || rb->Height != height) {
 323             /* could just as well pass rb->_ActualFormat here */
 324             if (rb->AllocStorage(ctx, rb, rb->InternalFormat, width, height)) {
 325                ASSERT(rb->Width == width);
 326                ASSERT(rb->Height == height);
 327             }
 328             else {
 329                _mesa_error(ctx, GL_OUT_OF_MEMORY, "Resizing framebuffer");
 330                /* no return */
 331             }
 332          }
 333       }
 334    }
 335
 336    if (fb->_DepthBuffer) {
 337       struct gl_renderbuffer *rb = fb->_DepthBuffer;
 338       if (rb->Width != width || rb->Height != height) {
 339          if (!rb->AllocStorage(ctx, rb, rb->InternalFormat, width, height)) {
 340             _mesa_error(ctx, GL_OUT_OF_MEMORY, "Resizing framebuffer");
 341          }
 342       }
 343    }
 344
 345    if (fb->_StencilBuffer) {
 346       struct gl_renderbuffer *rb = fb->_StencilBuffer;
 347       if (rb->Width != width || rb->Height != height) {
 348          if (!rb->AllocStorage(ctx, rb, rb->InternalFormat, width, height)) {
 349             _mesa_error(ctx, GL_OUT_OF_MEMORY, "Resizing framebuffer");
 350          }
 351       }
 352    }
 353
 354    fb->Width = width;
 355    fb->Height = height;
 356
 357    if (ctx) {
 358       /* update scissor / window bounds */
 359       _mesa_update_draw_buffer_bounds(ctx);
 360       /* Signal new buffer state so that swrast will update its clipping
 361        * info (the CLIP_BIT flag).
 362        */
 363       ctx->NewState |= _NEW_BUFFERS;
 364    }
 365 }
 366
 367
 368 /**
 369  * Examine all the framebuffer's renderbuffers to update the Width/Height
 370  * fields of the framebuffer.  If we have renderbuffers with different
 371  * sizes, set the framebuffer's width and height to zero.
 372  * Note: this is only intended for user-created framebuffers, not
 373  * window-system framebuffes.
 374  */
 375 static void
 376 update_framebuffer_size(struct gl_framebuffer *fb)
 377 {
 378    GLboolean haveSize = GL_FALSE;
 379    GLuint i;
 380
 381    /* user-created framebuffers only */
 382    assert(fb->Name);
 383
 384    for (i = 0; i < BUFFER_COUNT; i++) {
 385       struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
 386       const struct gl_renderbuffer *rb = att->Renderbuffer;
 387       if (rb) {
 388          if (haveSize) {
 389             if (rb->Width != fb->Width && rb->Height != fb->Height) {
 390                /* size mismatch! */
 391                fb->Width = 0;
 392                fb->Height = 0;
 393                return;
 394             }
 395          }
 396          else {
 397             fb->Width = rb->Width;
 398             fb->Height = rb->Height;
 399             haveSize = GL_TRUE;
 400          }
 401       }
 402    }
 403 }
 404
 405
 406 /**
 407  * Update the context's current drawing buffer's Xmin, Xmax, Ymin, Ymax fields.
 408  * These values are computed from the buffer's width and height and
 409  * the scissor box, if it's enabled.
 410  * \param ctx  the GL context.
 411  */
 412 void
 413 _mesa_update_draw_buffer_bounds(GLcontext *ctx)
 414 {
 415    struct gl_framebuffer *buffer = ctx->DrawBuffer;
 416
 417    if (!buffer)
 418       return;
 419
 420    if (buffer->Name) {
 421       /* user-created framebuffer size depends on the renderbuffers */
 422       update_framebuffer_size(buffer);
 423    }
 424
 425    buffer->_Xmin = 0;
 426    buffer->_Ymin = 0;
 427    buffer->_Xmax = buffer->Width;
 428    buffer->_Ymax = buffer->Height;
 429
 430    if (ctx->Scissor.Enabled) {
 431       if (ctx->Scissor.X > buffer->_Xmin) {
 432          buffer->_Xmin = ctx->Scissor.X;
 433       }
 434       if (ctx->Scissor.Y > buffer->_Ymin) {
 435          buffer->_Ymin = ctx->Scissor.Y;
 436       }
 437       if (ctx->Scissor.X + ctx->Scissor.Width < buffer->_Xmax) {
 438          buffer->_Xmax = ctx->Scissor.X + ctx->Scissor.Width;
 439       }
 440       if (ctx->Scissor.Y + ctx->Scissor.Height < buffer->_Ymax) {
 441          buffer->_Ymax = ctx->Scissor.Y + ctx->Scissor.Height;
 442       }
 443       /* finally, check for empty region */
 444       if (buffer->_Xmin > buffer->_Xmax) {
 445          buffer->_Xmin = buffer->_Xmax;
 446       }
 447       if (buffer->_Ymin > buffer->_Ymax) {
 448          buffer->_Ymin = buffer->_Ymax;
 449       }
 450    }
 451
 452    ASSERT(buffer->_Xmin <= buffer->_Xmax);
 453    ASSERT(buffer->_Ymin <= buffer->_Ymax);
 454 }
 455
 456
 457 /**
 458  * The glGet queries of the framebuffer red/green/blue size, stencil size,
 459  * etc. are satisfied by the fields of ctx->DrawBuffer->Visual.  These can
 460  * change depending on the renderbuffer bindings.  This function updates
 461  * the given framebuffer's Visual from the current renderbuffer bindings.
 462  *
 463  * This may apply to user-created framebuffers or window system framebuffers.
 464  *
 465  * Also note: ctx->DrawBuffer->Visual.depthBits might not equal
 466  * ctx->DrawBuffer->Attachment[BUFFER_DEPTH].Renderbuffer.DepthBits.
 467  * The former one is used to convert floating point depth values into
 468  * integer Z values.
 469  */
 470 void
 471 _mesa_update_framebuffer_visual(struct gl_framebuffer *fb)
 472 {
 473    GLuint i;
 474
 475    _mesa_bzero(&fb->Visual, sizeof(fb->Visual));
 476    fb->Visual.rgbMode = GL_TRUE; /* assume this */
 477
 478 #if 0 /* this _might_ be needed */
 479    if (fb->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
 480       /* leave visual fields zero'd */
 481       return;
 482    }
 483 #endif
 484
 485    /* find first RGB or CI renderbuffer */
 486    for (i = 0; i < BUFFER_COUNT; i++) {
 487       if (fb->Attachment[i].Renderbuffer) {
 488          const struct gl_renderbuffer *rb = fb->Attachment[i].Renderbuffer;
 489          if (rb->_BaseFormat == GL_RGBA || rb->_BaseFormat == GL_RGB) {
 490             fb->Visual.redBits = rb->RedBits;
 491             fb->Visual.greenBits = rb->GreenBits;
 492             fb->Visual.blueBits = rb->BlueBits;
 493             fb->Visual.alphaBits = rb->AlphaBits;
 494             fb->Visual.rgbBits = fb->Visual.redBits
 495                + fb->Visual.greenBits + fb->Visual.blueBits;
 496             fb->Visual.floatMode = GL_FALSE;
 497             break;
 498          }
 499          else if (rb->_BaseFormat == GL_COLOR_INDEX) {
 500             fb->Visual.indexBits = rb->IndexBits;
 501             fb->Visual.rgbMode = GL_FALSE;
 502             break;
 503          }
 504       }
 505    }
 506
 507    if (fb->Attachment[BUFFER_DEPTH].Renderbuffer) {
 508       fb->Visual.haveDepthBuffer = GL_TRUE;
 509       fb->Visual.depthBits
 510          = fb->Attachment[BUFFER_DEPTH].Renderbuffer->DepthBits;
 511    }
 512
 513    if (fb->Attachment[BUFFER_STENCIL].Renderbuffer) {
 514       fb->Visual.haveStencilBuffer = GL_TRUE;
 515       fb->Visual.stencilBits
 516          = fb->Attachment[BUFFER_STENCIL].Renderbuffer->StencilBits;
 517    }
 518
 519    if (fb->Attachment[BUFFER_ACCUM].Renderbuffer) {
 520       fb->Visual.haveAccumBuffer = GL_TRUE;
 521       fb->Visual.accumRedBits
 522          = fb->Attachment[BUFFER_DEPTH].Renderbuffer->RedBits;
 523       fb->Visual.accumGreenBits
 524          = fb->Attachment[BUFFER_DEPTH].Renderbuffer->GreenBits;
 525       fb->Visual.accumBlueBits
 526          = fb->Attachment[BUFFER_DEPTH].Renderbuffer->BlueBits;
 527       fb->Visual.accumAlphaBits
 528          = fb->Attachment[BUFFER_DEPTH].Renderbuffer->AlphaBits;
 529    }
 530
 531    compute_depth_max(fb);
 532 }
 533
 534
 535 /**
 536  * Update the framebuffer's _DepthBuffer field using the renderbuffer
 537  * found at the given attachment index.
 538  *
 539  * If that attachment points to a combined GL_DEPTH_STENCIL renderbuffer,
 540  * create and install a depth wrapper/adaptor.
 541  *
 542  * \param fb  the framebuffer whose _DepthBuffer field to update
 543  * \param attIndex  indicates the renderbuffer to possibly wrap
 544  */
 545 void
 546 _mesa_update_depth_buffer(GLcontext *ctx,
 547                           struct gl_framebuffer *fb,
 548                           GLuint attIndex)
 549 {
 550    struct gl_renderbuffer *depthRb;
 551
 552    /* only one possiblity for now */
 553    ASSERT(attIndex == BUFFER_DEPTH);
 554
 555    depthRb = fb->Attachment[attIndex].Renderbuffer;
 556
 557    if (depthRb && depthRb->_ActualFormat == GL_DEPTH24_STENCIL8_EXT) {
 558       /* The attached depth buffer is a GL_DEPTH_STENCIL renderbuffer */
 559       if (!fb->_DepthBuffer
 560           || fb->_DepthBuffer->Wrapped != depthRb
 561           || fb->_DepthBuffer->_BaseFormat != GL_DEPTH_COMPONENT) {
 562          /* need to update wrapper */
 563          struct gl_renderbuffer *wrapper
 564             = _mesa_new_z24_renderbuffer_wrapper(ctx, depthRb);
 565          set_depth_renderbuffer(fb, wrapper);
 566          ASSERT(fb->_DepthBuffer->Wrapped == depthRb);
 567       }
 568    }
 569    else {
 570       /* depthRb may be null */
 571       set_depth_renderbuffer(fb, depthRb);
 572    }
 573 }
 574
 575
 576 /**
 577  * Update the framebuffer's _StencilBuffer field using the renderbuffer
 578  * found at the given attachment index.
 579  *
 580  * If that attachment points to a combined GL_DEPTH_STENCIL renderbuffer,
 581  * create and install a stencil wrapper/adaptor.
 582  *
 583  * \param fb  the framebuffer whose _StencilBuffer field to update
 584  * \param attIndex  indicates the renderbuffer to possibly wrap
 585  */
 586 void
 587 _mesa_update_stencil_buffer(GLcontext *ctx,
 588                             struct gl_framebuffer *fb,
 589                             GLuint attIndex)
 590 {
 591    struct gl_renderbuffer *stencilRb;
 592
 593    ASSERT(attIndex == BUFFER_DEPTH ||
 594           attIndex == BUFFER_STENCIL);
 595
 596    stencilRb = fb->Attachment[attIndex].Renderbuffer;
 597
 598    if (stencilRb && stencilRb->_ActualFormat == GL_DEPTH24_STENCIL8_EXT) {
 599       /* The attached stencil buffer is a GL_DEPTH_STENCIL renderbuffer */
 600       if (!fb->_StencilBuffer
 601           || fb->_StencilBuffer->Wrapped != stencilRb
 602           || fb->_StencilBuffer->_BaseFormat != GL_STENCIL_INDEX) {
 603          /* need to update wrapper */
 604          struct gl_renderbuffer *wrapper
 605             = _mesa_new_s8_renderbuffer_wrapper(ctx, stencilRb);
 606          set_stencil_renderbuffer(fb, wrapper);
 607          ASSERT(fb->_StencilBuffer->Wrapped == stencilRb);
 608       }
 609    }
 610    else {
 611       /* stencilRb may be null */
 612       set_stencil_renderbuffer(fb, stencilRb);
 613    }
 614 }
 615
 616
 617 /**
 618  * Update the list of color drawing renderbuffer pointers.
 619  * Later, when we're rendering we'll loop from 0 to _NumColorDrawBuffers
 620  * writing colors.
 621  */
 622 static void
 623 update_color_draw_buffers(GLcontext *ctx, struct gl_framebuffer *fb)
 624 {
 625    GLuint output;
 626
 627    /*
 628     * Fragment programs can write to multiple colorbuffers with
 629     * the GL_ARB_draw_buffers extension.
 630     */
 631    for (output = 0; output < ctx->Const.MaxDrawBuffers; output++) {
 632       GLbitfield bufferMask = fb->_ColorDrawBufferMask[output];
 633       GLuint count = 0;
 634       GLuint i;
 635       if (!fb->DeletePending) {
 636          /* We need the inner loop here because glDrawBuffer(GL_FRONT_AND_BACK)
 637           * can specify writing to two or four color buffers (for example).
 638           */
 639          for (i = 0; bufferMask && i < BUFFER_COUNT; i++) {
 640             const GLuint bufferBit = 1 << i;
 641             if (bufferBit & bufferMask) {
 642                struct gl_renderbuffer *rb = fb->Attachment[i].Renderbuffer;
 643                if (rb) {
 644                   fb->_ColorDrawBuffers[output][count] = rb;
 645                   count++;
 646                }
 647                else {
 648                   /*
 649                   _mesa_warning(ctx, "DrawBuffer names a missing buffer!\n");
 650                   */
 651                }
 652                bufferMask &= ~bufferBit;
 653             }
 654          }
 655       }
 656       fb->_NumColorDrawBuffers[output] = count;
 657    }
 658 }
 659
 660
 661 /**
 662  * Update the color read renderbuffer pointer.
 663  * Unlike the DrawBuffer, we can only read from one (or zero) color buffers.
 664  */
 665 static void
 666 update_color_read_buffer(GLcontext *ctx, struct gl_framebuffer *fb)
 667 {
 668    (void) ctx;
 669    if (fb->_ColorReadBufferIndex == -1 || fb->DeletePending) {
 670       fb->_ColorReadBuffer = NULL; /* legal! */
 671    }
 672    else {
 673       ASSERT(fb->_ColorReadBufferIndex >= 0);
 674       ASSERT(fb->_ColorReadBufferIndex < BUFFER_COUNT);
 675       fb->_ColorReadBuffer
 676          = fb->Attachment[fb->_ColorReadBufferIndex].Renderbuffer;
 677    }
 678 }
 679
 680
 681 /**
 682  * Update state related to the current draw/read framebuffers.
 683  * Specifically, update these framebuffer fields:
 684  *    _ColorDrawBuffers
 685  *    _NumColorDrawBuffers
 686  *    _ColorReadBuffer
 687  *    _DepthBuffer
 688  *    _StencilBuffer
 689  * If the current framebuffer is user-created, make sure it's complete.
 690  * The following functions can effect this state:  glReadBuffer,
 691  * glDrawBuffer, glDrawBuffersARB, glFramebufferRenderbufferEXT,
 692  * glRenderbufferStorageEXT.
 693  */
 694 void
 695 _mesa_update_framebuffer(GLcontext *ctx)
 696 {
 697    struct gl_framebuffer *fb = ctx->DrawBuffer;
 698
 699    /* Completeness only matters for user-created framebuffers */
 700    if (fb->Name != 0) {
 701       _mesa_test_framebuffer_completeness(ctx, fb);
 702       _mesa_update_framebuffer_visual(fb);
 703    }
 704
 705    update_color_draw_buffers(ctx, fb);
 706    update_color_read_buffer(ctx, fb);
 707    _mesa_update_depth_buffer(ctx, fb, BUFFER_DEPTH);
 708    _mesa_update_stencil_buffer(ctx, fb, BUFFER_STENCIL);
 709
 710    compute_depth_max(fb);
 711 }
 712
 713
 714 /**
 715  * Check if the renderbuffer for a read operation (glReadPixels, glCopyPixels,
 716  * glCopyTex[Sub]Image, etc. exists.
 717  * \param format  a basic image format such as GL_RGB, GL_RGBA, GL_ALPHA,
 718  *                GL_DEPTH_COMPONENT, etc. or GL_COLOR, GL_DEPTH, GL_STENCIL.
 719  * \return GL_TRUE if buffer exists, GL_FALSE otherwise
 720  */
 721 GLboolean
 722 _mesa_source_buffer_exists(GLcontext *ctx, GLenum format)
 723 {
 724    const struct gl_renderbuffer_attachment *att
 725       = ctx->ReadBuffer->Attachment;
 726
 727    if (ctx->ReadBuffer->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
 728       return GL_FALSE;
 729    }
 730
 731    switch (format) {
 732    case GL_COLOR:
 733    case GL_RED:
 734    case GL_GREEN:
 735    case GL_BLUE:
 736    case GL_ALPHA:
 737    case GL_LUMINANCE:
 738    case GL_LUMINANCE_ALPHA:
 739    case GL_INTENSITY:
 740    case GL_RGB:
 741    case GL_BGR:
 742    case GL_RGBA:
 743    case GL_BGRA:
 744    case GL_ABGR_EXT:
 745    case GL_COLOR_INDEX:
 746       if (ctx->ReadBuffer->_ColorReadBuffer == NULL) {
 747          return GL_FALSE;
 748       }
 749       /* XXX enable this post 6.5 release:
 750       ASSERT(ctx->ReadBuffer->_ColorReadBuffer->RedBits > 0 ||
 751              ctx->ReadBuffer->_ColorReadBuffer->IndexBits > 0);
 752       */
 753       break;
 754    case GL_DEPTH:
 755    case GL_DEPTH_COMPONENT:
 756       if (!att[BUFFER_DEPTH].Renderbuffer) {
 757          return GL_FALSE;
 758       }
 759       ASSERT(att[BUFFER_DEPTH].Renderbuffer->DepthBits > 0);
 760       break;
 761    case GL_STENCIL:
 762    case GL_STENCIL_INDEX:
 763       if (!att[BUFFER_STENCIL].Renderbuffer) {
 764          return GL_FALSE;
 765       }
 766       ASSERT(att[BUFFER_STENCIL].Renderbuffer->StencilBits > 0);
 767       break;
 768    case GL_DEPTH_STENCIL_EXT:
 769       if (!att[BUFFER_DEPTH].Renderbuffer ||
 770           !att[BUFFER_STENCIL].Renderbuffer) {
 771          return GL_FALSE;
 772       }
 773       ASSERT(att[BUFFER_DEPTH].Renderbuffer->DepthBits > 0);
 774       ASSERT(att[BUFFER_STENCIL].Renderbuffer->StencilBits > 0);
 775       break;
 776    default:
 777       _mesa_problem(ctx,
 778                     "Unexpected format 0x%x in _mesa_source_buffer_exists",
 779                     format);
 780       return GL_FALSE;
 781    }
 782
 783    /* OK */
 784    return GL_TRUE;
 785 }
 786
 787
 788 /**
 789  * As above, but for drawing operations.
 790  * XXX code do some code merging w/ above function.
 791  */
 792 GLboolean
 793 _mesa_dest_buffer_exists(GLcontext *ctx, GLenum format)
 794 {
 795    const struct gl_renderbuffer_attachment *att
 796       = ctx->ReadBuffer->Attachment;
 797
 798    if (ctx->DrawBuffer->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
 799       return GL_FALSE;
 800    }
 801
 802    switch (format) {
 803    case GL_COLOR:
 804    case GL_RED:
 805    case GL_GREEN:
 806    case GL_BLUE:
 807    case GL_ALPHA:
 808    case GL_LUMINANCE:
 809    case GL_LUMINANCE_ALPHA:
 810    case GL_INTENSITY:
 811    case GL_RGB:
 812    case GL_BGR:
 813    case GL_RGBA:
 814    case GL_BGRA:
 815    case GL_ABGR_EXT:
 816    case GL_COLOR_INDEX:
 817       /* nothing special */
 818       /* Could assert that colorbuffer has RedBits > 0 */
 819       break;
 820    case GL_DEPTH:
 821    case GL_DEPTH_COMPONENT:
 822       if (!att[BUFFER_DEPTH].Renderbuffer) {
 823          return GL_FALSE;
 824       }
 825       ASSERT(att[BUFFER_DEPTH].Renderbuffer->DepthBits > 0);
 826       break;
 827    case GL_STENCIL:
 828    case GL_STENCIL_INDEX:
 829       if (!att[BUFFER_STENCIL].Renderbuffer) {
 830          return GL_FALSE;
 831       }
 832       ASSERT(att[BUFFER_STENCIL].Renderbuffer->StencilBits > 0);
 833       break;
 834    case GL_DEPTH_STENCIL_EXT:
 835       if (!att[BUFFER_DEPTH].Renderbuffer ||
 836           !att[BUFFER_STENCIL].Renderbuffer) {
 837          return GL_FALSE;
 838       }
 839       ASSERT(att[BUFFER_DEPTH].Renderbuffer->DepthBits > 0);
 840       ASSERT(att[BUFFER_STENCIL].Renderbuffer->StencilBits > 0);
 841       break;
 842    default:
 843       _mesa_problem(ctx,
 844                     "Unexpected format 0x%x in _mesa_source_buffer_exists",
 845                     format);
 846       return GL_FALSE;
 847    }
 848
 849    /* OK */
 850    return GL_TRUE;
 851 }