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 "buffers.h"
  36 #include "context.h"
  37 #include "depthstencil.h"
  38 #include "mtypes.h"
  39 #include "fbobject.h"
  40 #include "framebuffer.h"
  41 #include "renderbuffer.h"
  42 #include "texobj.h"
  43
  44
  45
  46 /**
  47  * Compute/set the _DepthMax field for the given framebuffer.
  48  * This value depends on the Z buffer resolution.
  49  */
  50 static void
  51 compute_depth_max(struct gl_framebuffer *fb)
  52 {
  53    if (fb->Visual.depthBits == 0) {
  54       /* Special case.  Even if we don't have a depth buffer we need
  55        * good values for DepthMax for Z vertex transformation purposes
  56        * and for per-fragment fog computation.
  57        */
  58       fb->_DepthMax = (1 << 16) - 1;
  59    }
  60    else if (fb->Visual.depthBits < 32) {
  61       fb->_DepthMax = (1 << fb->Visual.depthBits) - 1;
  62    }
  63    else {
  64       /* Special case since shift values greater than or equal to the
  65        * number of bits in the left hand expression's type are undefined.
  66        */
  67       fb->_DepthMax = 0xffffffff;
  68    }
  69    fb->_DepthMaxF = (GLfloat) fb->_DepthMax;
  70
  71    /* Minimum resolvable depth value, for polygon offset */
  72    fb->_MRD = 1.0 / fb->_DepthMaxF;
  73 }
  74
  75
  76 /**
  77  * Create and initialize a gl_framebuffer object.
  78  * This is intended for creating _window_system_ framebuffers, not generic
  79  * framebuffer objects ala GL_EXT_framebuffer_object.
  80  *
  81  * \sa _mesa_new_framebuffer
  82  */
  83 struct gl_framebuffer *
  84 _mesa_create_framebuffer(const GLvisual *visual)
  85 {
  86    struct gl_framebuffer *fb = CALLOC_STRUCT(gl_framebuffer);
  87    assert(visual);
  88    if (fb) {
  89       _mesa_initialize_framebuffer(fb, visual);
  90    }
  91    return fb;
  92 }
  93
  94
  95 /**
  96  * Allocate a new gl_framebuffer object.
  97  * This is the default function for ctx->Driver.NewFramebuffer().
  98  * This is for allocating user-created framebuffers, not window-system
  99  * framebuffers!
 100  * \sa _mesa_create_framebuffer
 101  */
 102 struct gl_framebuffer *
 103 _mesa_new_framebuffer(GLcontext *ctx, GLuint name)
 104 {
 105    struct gl_framebuffer *fb;
 106    (void) ctx;
 107    assert(name != 0);
 108    fb = CALLOC_STRUCT(gl_framebuffer);
 109    if (fb) {
 110       fb->Name = name;
 111       fb->RefCount = 1;
 112       fb->_NumColorDrawBuffers = 1;
 113       fb->ColorDrawBuffer[0] = GL_COLOR_ATTACHMENT0_EXT;
 114       fb->_ColorDrawBufferIndexes[0] = BUFFER_COLOR0;
 115       fb->ColorReadBuffer = GL_COLOR_ATTACHMENT0_EXT;
 116       fb->_ColorReadBufferIndex = BUFFER_COLOR0;
 117       fb->Delete = _mesa_destroy_framebuffer;
 118    }
 119    return fb;
 120 }
 121
 122
 123 /**
 124  * Initialize a gl_framebuffer object.  Typically used to initialize
 125  * window system-created framebuffers, not user-created framebuffers.
 126  * \sa _mesa_create_framebuffer
 127  */
 128 void
 129 _mesa_initialize_framebuffer(struct gl_framebuffer *fb, const GLvisual *visual)
 130 {
 131    assert(fb);
 132    assert(visual);
 133
 134    _mesa_bzero(fb, sizeof(struct gl_framebuffer));
 135
 136    _glthread_INIT_MUTEX(fb->Mutex);
 137
 138    fb->RefCount = 1;
 139
 140    /* save the visual */
 141    fb->Visual = *visual;
 142
 143    /* Init read/draw renderbuffer state */
 144    if (visual->doubleBufferMode) {
 145       fb->_NumColorDrawBuffers = 1;
 146       fb->ColorDrawBuffer[0] = GL_BACK;
 147       fb->_ColorDrawBufferIndexes[0] = BUFFER_BACK_LEFT;
 148       fb->ColorReadBuffer = GL_BACK;
 149       fb->_ColorReadBufferIndex = BUFFER_BACK_LEFT;
 150    }
 151    else {
 152       fb->_NumColorDrawBuffers = 1;
 153       fb->ColorDrawBuffer[0] = GL_FRONT;
 154       fb->_ColorDrawBufferIndexes[0] = BUFFER_FRONT_LEFT;
 155       fb->ColorReadBuffer = GL_FRONT;
 156       fb->_ColorReadBufferIndex = BUFFER_FRONT_LEFT;
 157    }
 158
 159    fb->Delete = _mesa_destroy_framebuffer;
 160    fb->_Status = GL_FRAMEBUFFER_COMPLETE_EXT;
 161
 162    compute_depth_max(fb);
 163 }
 164
 165
 166 /**
 167  * Deallocate buffer and everything attached to it.
 168  * Typically called via the gl_framebuffer->Delete() method.
 169  */
 170 void
 171 _mesa_destroy_framebuffer(struct gl_framebuffer *fb)
 172 {
 173    if (fb) {
 174       _mesa_free_framebuffer_data(fb);
 175       _mesa_free(fb);
 176    }
 177 }
 178
 179
 180 /**
 181  * Free all the data hanging off the given gl_framebuffer, but don't free
 182  * the gl_framebuffer object itself.
 183  */
 184 void
 185 _mesa_free_framebuffer_data(struct gl_framebuffer *fb)
 186 {
 187    GLuint i;
 188
 189    assert(fb);
 190    assert(fb->RefCount == 0);
 191
 192    _glthread_DESTROY_MUTEX(fb->Mutex);
 193
 194    for (i = 0; i < BUFFER_COUNT; i++) {
 195       struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
 196       if (att->Renderbuffer) {
 197          _mesa_reference_renderbuffer(&att->Renderbuffer, NULL);
 198       }
 199       if (att->Texture) {
 200          _mesa_reference_texobj(&att->Texture, NULL);
 201       }
 202       ASSERT(!att->Renderbuffer);
 203       ASSERT(!att->Texture);
 204       att->Type = GL_NONE;
 205    }
 206
 207    /* unbind _Depth/_StencilBuffer to decr ref counts */
 208    _mesa_reference_renderbuffer(&fb->_DepthBuffer, NULL);
 209    _mesa_reference_renderbuffer(&fb->_StencilBuffer, NULL);
 210 }
 211
 212
 213 /**
 214  * Set *ptr to point to fb, with refcounting and locking.
 215  */
 216 void
 217 _mesa_reference_framebuffer(struct gl_framebuffer **ptr,
 218                             struct gl_framebuffer *fb)
 219 {
 220    assert(ptr);
 221    if (*ptr == fb) {
 222       /* no change */
 223       return;
 224    }
 225    if (*ptr) {
 226       _mesa_unreference_framebuffer(ptr);
 227    }
 228    assert(!*ptr);
 229    assert(fb);
 230    _glthread_LOCK_MUTEX(fb->Mutex);
 231    fb->RefCount++;
 232    _glthread_UNLOCK_MUTEX(fb->Mutex);
 233    *ptr = fb;
 234 }
 235
 236
 237 /**
 238  * Undo/remove a reference to a framebuffer object.
 239  * Decrement the framebuffer object's reference count and delete it when
 240  * the refcount hits zero.
 241  * Note: we pass the address of a pointer and set it to NULL.
 242  */
 243 void
 244 _mesa_unreference_framebuffer(struct gl_framebuffer **fb)
 245 {
 246    assert(fb);
 247    if (*fb) {
 248       GLboolean deleteFlag = GL_FALSE;
 249
 250       _glthread_LOCK_MUTEX((*fb)->Mutex);
 251       ASSERT((*fb)->RefCount > 0);
 252       (*fb)->RefCount--;
 253       deleteFlag = ((*fb)->RefCount == 0);
 254       _glthread_UNLOCK_MUTEX((*fb)->Mutex);
 255
 256       if (deleteFlag)
 257          (*fb)->Delete(*fb);
 258
 259       *fb = NULL;
 260    }
 261 }
 262
 263
 264
 265
 266 /**
 267  * Resize the given framebuffer's renderbuffers to the new width and height.
 268  * This should only be used for window-system framebuffers, not
 269  * user-created renderbuffers (i.e. made with GL_EXT_framebuffer_object).
 270  * This will typically be called via ctx->Driver.ResizeBuffers() or directly
 271  * from a device driver.
 272  *
 273  * \note it's possible for ctx to be null since a window can be resized
 274  * without a currently bound rendering context.
 275  */
 276 void
 277 _mesa_resize_framebuffer(GLcontext *ctx, struct gl_framebuffer *fb,
 278                          GLuint width, GLuint height)
 279 {
 280    GLuint i;
 281
 282    /* XXX I think we could check if the size is not changing
 283     * and return early.
 284     */
 285
 286    /* For window system framebuffers, Name is zero */
 287    assert(fb->Name == 0);
 288
 289    for (i = 0; i < BUFFER_COUNT; i++) {
 290       struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
 291       if (att->Type == GL_RENDERBUFFER_EXT && att->Renderbuffer) {
 292          struct gl_renderbuffer *rb = att->Renderbuffer;
 293          /* only resize if size is changing */
 294          if (rb->Width != width || rb->Height != height) {
 295             /* could just as well pass rb->_ActualFormat here */
 296             if (rb->AllocStorage(ctx, rb, rb->InternalFormat, width, height)) {
 297                ASSERT(rb->Width == width);
 298                ASSERT(rb->Height == height);
 299             }
 300             else {
 301                _mesa_error(ctx, GL_OUT_OF_MEMORY, "Resizing framebuffer");
 302                /* no return */
 303             }
 304          }
 305       }
 306    }
 307
 308    if (fb->_DepthBuffer) {
 309       struct gl_renderbuffer *rb = fb->_DepthBuffer;
 310       if (rb->Width != width || rb->Height != height) {
 311          if (!rb->AllocStorage(ctx, rb, rb->InternalFormat, width, height)) {
 312             _mesa_error(ctx, GL_OUT_OF_MEMORY, "Resizing framebuffer");
 313          }
 314       }
 315    }
 316
 317    if (fb->_StencilBuffer) {
 318       struct gl_renderbuffer *rb = fb->_StencilBuffer;
 319       if (rb->Width != width || rb->Height != height) {
 320          if (!rb->AllocStorage(ctx, rb, rb->InternalFormat, width, height)) {
 321             _mesa_error(ctx, GL_OUT_OF_MEMORY, "Resizing framebuffer");
 322          }
 323       }
 324    }
 325
 326    fb->Width = width;
 327    fb->Height = height;
 328
 329    if (ctx) {
 330       /* update scissor / window bounds */
 331       _mesa_update_draw_buffer_bounds(ctx);
 332       /* Signal new buffer state so that swrast will update its clipping
 333        * info (the CLIP_BIT flag).
 334        */
 335       ctx->NewState |= _NEW_BUFFERS;
 336    }
 337 }
 338
 339
 340 /**
 341  * Examine all the framebuffer's renderbuffers to update the Width/Height
 342  * fields of the framebuffer.  If we have renderbuffers with different
 343  * sizes, set the framebuffer's width and height to zero.
 344  * Note: this is only intended for user-created framebuffers, not
 345  * window-system framebuffes.
 346  */
 347 static void
 348 update_framebuffer_size(struct gl_framebuffer *fb)
 349 {
 350    GLboolean haveSize = GL_FALSE;
 351    GLuint i;
 352
 353    /* user-created framebuffers only */
 354    assert(fb->Name);
 355
 356    for (i = 0; i < BUFFER_COUNT; i++) {
 357       struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
 358       const struct gl_renderbuffer *rb = att->Renderbuffer;
 359       if (rb) {
 360          if (haveSize) {
 361             if (rb->Width != fb->Width && rb->Height != fb->Height) {
 362                /* size mismatch! */
 363                fb->Width = 0;
 364                fb->Height = 0;
 365                return;
 366             }
 367          }
 368          else {
 369             fb->Width = rb->Width;
 370             fb->Height = rb->Height;
 371             haveSize = GL_TRUE;
 372          }
 373       }
 374    }
 375 }
 376
 377
 378 /**
 379  * Update the context's current drawing buffer's Xmin, Xmax, Ymin, Ymax fields.
 380  * These values are computed from the buffer's width and height and
 381  * the scissor box, if it's enabled.
 382  * \param ctx  the GL context.
 383  */
 384 void
 385 _mesa_update_draw_buffer_bounds(GLcontext *ctx)
 386 {
 387    struct gl_framebuffer *buffer = ctx->DrawBuffer;
 388
 389    if (!buffer)
 390       return;
 391
 392    if (buffer->Name) {
 393       /* user-created framebuffer size depends on the renderbuffers */
 394       update_framebuffer_size(buffer);
 395    }
 396
 397    buffer->_Xmin = 0;
 398    buffer->_Ymin = 0;
 399    buffer->_Xmax = buffer->Width;
 400    buffer->_Ymax = buffer->Height;
 401
 402    if (ctx->Scissor.Enabled) {
 403       if (ctx->Scissor.X > buffer->_Xmin) {
 404          buffer->_Xmin = ctx->Scissor.X;
 405       }
 406       if (ctx->Scissor.Y > buffer->_Ymin) {
 407          buffer->_Ymin = ctx->Scissor.Y;
 408       }
 409       if (ctx->Scissor.X + ctx->Scissor.Width < buffer->_Xmax) {
 410          buffer->_Xmax = ctx->Scissor.X + ctx->Scissor.Width;
 411       }
 412       if (ctx->Scissor.Y + ctx->Scissor.Height < buffer->_Ymax) {
 413          buffer->_Ymax = ctx->Scissor.Y + ctx->Scissor.Height;
 414       }
 415       /* finally, check for empty region */
 416       if (buffer->_Xmin > buffer->_Xmax) {
 417          buffer->_Xmin = buffer->_Xmax;
 418       }
 419       if (buffer->_Ymin > buffer->_Ymax) {
 420          buffer->_Ymin = buffer->_Ymax;
 421       }
 422    }
 423
 424    ASSERT(buffer->_Xmin <= buffer->_Xmax);
 425    ASSERT(buffer->_Ymin <= buffer->_Ymax);
 426 }
 427
 428
 429 /**
 430  * The glGet queries of the framebuffer red/green/blue size, stencil size,
 431  * etc. are satisfied by the fields of ctx->DrawBuffer->Visual.  These can
 432  * change depending on the renderbuffer bindings.  This function updates
 433  * the given framebuffer's Visual from the current renderbuffer bindings.
 434  *
 435  * This may apply to user-created framebuffers or window system framebuffers.
 436  *
 437  * Also note: ctx->DrawBuffer->Visual.depthBits might not equal
 438  * ctx->DrawBuffer->Attachment[BUFFER_DEPTH].Renderbuffer.DepthBits.
 439  * The former one is used to convert floating point depth values into
 440  * integer Z values.
 441  */
 442 void
 443 _mesa_update_framebuffer_visual(struct gl_framebuffer *fb)
 444 {
 445    GLuint i;
 446
 447    _mesa_bzero(&fb->Visual, sizeof(fb->Visual));
 448    fb->Visual.rgbMode = GL_TRUE; /* assume this */
 449
 450 #if 0 /* this _might_ be needed */
 451    if (fb->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
 452       /* leave visual fields zero'd */
 453       return;
 454    }
 455 #endif
 456
 457    /* find first RGB or CI renderbuffer */
 458    for (i = 0; i < BUFFER_COUNT; i++) {
 459       if (fb->Attachment[i].Renderbuffer) {
 460          const struct gl_renderbuffer *rb = fb->Attachment[i].Renderbuffer;
 461          if (rb->_BaseFormat == GL_RGBA || rb->_BaseFormat == GL_RGB) {
 462             fb->Visual.redBits = rb->RedBits;
 463             fb->Visual.greenBits = rb->GreenBits;
 464             fb->Visual.blueBits = rb->BlueBits;
 465             fb->Visual.alphaBits = rb->AlphaBits;
 466             fb->Visual.rgbBits = fb->Visual.redBits
 467                + fb->Visual.greenBits + fb->Visual.blueBits;
 468             fb->Visual.floatMode = GL_FALSE;
 469             break;
 470          }
 471          else if (rb->_BaseFormat == GL_COLOR_INDEX) {
 472             fb->Visual.indexBits = rb->IndexBits;
 473             fb->Visual.rgbMode = GL_FALSE;
 474             break;
 475          }
 476       }
 477    }
 478
 479    if (fb->Attachment[BUFFER_DEPTH].Renderbuffer) {
 480       fb->Visual.haveDepthBuffer = GL_TRUE;
 481       fb->Visual.depthBits
 482          = fb->Attachment[BUFFER_DEPTH].Renderbuffer->DepthBits;
 483    }
 484
 485    if (fb->Attachment[BUFFER_STENCIL].Renderbuffer) {
 486       fb->Visual.haveStencilBuffer = GL_TRUE;
 487       fb->Visual.stencilBits
 488          = fb->Attachment[BUFFER_STENCIL].Renderbuffer->StencilBits;
 489    }
 490
 491    if (fb->Attachment[BUFFER_ACCUM].Renderbuffer) {
 492       fb->Visual.haveAccumBuffer = GL_TRUE;
 493       fb->Visual.accumRedBits
 494          = fb->Attachment[BUFFER_DEPTH].Renderbuffer->RedBits;
 495       fb->Visual.accumGreenBits
 496          = fb->Attachment[BUFFER_DEPTH].Renderbuffer->GreenBits;
 497       fb->Visual.accumBlueBits
 498          = fb->Attachment[BUFFER_DEPTH].Renderbuffer->BlueBits;
 499       fb->Visual.accumAlphaBits
 500          = fb->Attachment[BUFFER_DEPTH].Renderbuffer->AlphaBits;
 501    }
 502
 503    compute_depth_max(fb);
 504 }
 505
 506
 507 /**
 508  * Update the framebuffer's _DepthBuffer field using the renderbuffer
 509  * found at the given attachment index.
 510  *
 511  * If that attachment points to a combined GL_DEPTH_STENCIL renderbuffer,
 512  * create and install a depth wrapper/adaptor.
 513  *
 514  * \param fb  the framebuffer whose _DepthBuffer field to update
 515  * \param attIndex  indicates the renderbuffer to possibly wrap
 516  */
 517 void
 518 _mesa_update_depth_buffer(GLcontext *ctx,
 519                           struct gl_framebuffer *fb,
 520                           GLuint attIndex)
 521 {
 522    struct gl_renderbuffer *depthRb;
 523
 524    /* only one possiblity for now */
 525    ASSERT(attIndex == BUFFER_DEPTH);
 526
 527    depthRb = fb->Attachment[attIndex].Renderbuffer;
 528
 529    if (depthRb && depthRb->_ActualFormat == GL_DEPTH24_STENCIL8_EXT) {
 530       /* The attached depth buffer is a GL_DEPTH_STENCIL renderbuffer */
 531       if (!fb->_DepthBuffer
 532           || fb->_DepthBuffer->Wrapped != depthRb
 533           || fb->_DepthBuffer->_BaseFormat != GL_DEPTH_COMPONENT) {
 534          /* need to update wrapper */
 535          struct gl_renderbuffer *wrapper
 536             = _mesa_new_z24_renderbuffer_wrapper(ctx, depthRb);
 537          _mesa_reference_renderbuffer(&fb->_DepthBuffer, wrapper);
 538          ASSERT(fb->_DepthBuffer->Wrapped == depthRb);
 539       }
 540    }
 541    else {
 542       /* depthRb may be null */
 543       _mesa_reference_renderbuffer(&fb->_DepthBuffer, depthRb);
 544    }
 545 }
 546
 547
 548 /**
 549  * Update the framebuffer's _StencilBuffer field using the renderbuffer
 550  * found at the given attachment index.
 551  *
 552  * If that attachment points to a combined GL_DEPTH_STENCIL renderbuffer,
 553  * create and install a stencil wrapper/adaptor.
 554  *
 555  * \param fb  the framebuffer whose _StencilBuffer field to update
 556  * \param attIndex  indicates the renderbuffer to possibly wrap
 557  */
 558 void
 559 _mesa_update_stencil_buffer(GLcontext *ctx,
 560                             struct gl_framebuffer *fb,
 561                             GLuint attIndex)
 562 {
 563    struct gl_renderbuffer *stencilRb;
 564
 565    ASSERT(attIndex == BUFFER_DEPTH ||
 566           attIndex == BUFFER_STENCIL);
 567
 568    stencilRb = fb->Attachment[attIndex].Renderbuffer;
 569
 570    if (stencilRb && stencilRb->_ActualFormat == GL_DEPTH24_STENCIL8_EXT) {
 571       /* The attached stencil buffer is a GL_DEPTH_STENCIL renderbuffer */
 572       if (!fb->_StencilBuffer
 573           || fb->_StencilBuffer->Wrapped != stencilRb
 574           || fb->_StencilBuffer->_BaseFormat != GL_STENCIL_INDEX) {
 575          /* need to update wrapper */
 576          struct gl_renderbuffer *wrapper
 577             = _mesa_new_s8_renderbuffer_wrapper(ctx, stencilRb);
 578          _mesa_reference_renderbuffer(&fb->_StencilBuffer, wrapper);
 579          ASSERT(fb->_StencilBuffer->Wrapped == stencilRb);
 580       }
 581    }
 582    else {
 583       /* stencilRb may be null */
 584       _mesa_reference_renderbuffer(&fb->_StencilBuffer, stencilRb);
 585    }
 586 }
 587
 588
 589 /*
 590  * Example DrawBuffers scenarios:
 591  *
 592  * 1. glDrawBuffer(GL_FRONT_AND_BACK), fixed-func or shader writes to
 593  * "gl_FragColor" or program writes to the "result.color" register:
 594  *
 595  *   fragment color output   renderbuffer
 596  *   ---------------------   ---------------
 597  *   color[0]                Front, Back
 598  *
 599  *
 600  * 2. glDrawBuffers(3, [GL_FRONT, GL_AUX0, GL_AUX1]), shader writes to
 601  * gl_FragData[i] or program writes to result.color[i] registers:
 602  *
 603  *   fragment color output   renderbuffer
 604  *   ---------------------   ---------------
 605  *   color[0]                Front
 606  *   color[1]                Aux0
 607  *   color[3]                Aux1
 608  *
 609  *
 610  * 3. glDrawBuffers(3, [GL_FRONT, GL_AUX0, GL_AUX1]) and shader writes to
 611  * gl_FragColor, or fixed function:
 612  *
 613  *   fragment color output   renderbuffer
 614  *   ---------------------   ---------------
 615  *   color[0]                Front, Aux0, Aux1
 616  *
 617  *
 618  * In either case, the list of renderbuffers is stored in the
 619  * framebuffer->_ColorDrawBuffers[] array and
 620  * framebuffer->_NumColorDrawBuffers indicates the number of buffers.
 621  * The renderer (like swrast) has to look at the current fragment shader
 622  * to see if it writes to gl_FragColor vs. gl_FragData[i] to determine
 623  * how to map color outputs to renderbuffers.
 624  *
 625  * Note that these two calls are equivalent (for fixed function fragment
 626  * shading anyway):
 627  *   a)  glDrawBuffer(GL_FRONT_AND_BACK);  (assuming non-stereo framebuffer)
 628  *   b)  glDrawBuffers(2, [GL_FRONT_LEFT, GL_BACK_LEFT]);
 629  */
 630
 631
 632
 633
 634 /**
 635  * Update the (derived) list of color drawing renderbuffer pointers.
 636  * Later, when we're rendering we'll loop from 0 to _NumColorDrawBuffers
 637  * writing colors.
 638  */
 639 static void
 640 update_color_draw_buffers(GLcontext *ctx, struct gl_framebuffer *fb)
 641 {
 642    GLuint output;
 643
 644    /* set 0th buffer to NULL now in case _NumColorDrawBuffers is zero */
 645    fb->_ColorDrawBuffers[0] = NULL;
 646
 647    for (output = 0; output < fb->_NumColorDrawBuffers; output++) {
 648       GLint buf = fb->_ColorDrawBufferIndexes[output];
 649       if (buf >= 0) {
 650          fb->_ColorDrawBuffers[output] = fb->Attachment[buf].Renderbuffer;
 651       }
 652       else {
 653          fb->_ColorDrawBuffers[output] = NULL;
 654       }
 655    }
 656 }
 657
 658
 659 /**
 660  * Update the (derived) color read renderbuffer pointer.
 661  * Unlike the DrawBuffer, we can only read from one (or zero) color buffers.
 662  */
 663 static void
 664 update_color_read_buffer(GLcontext *ctx, struct gl_framebuffer *fb)
 665 {
 666    (void) ctx;
 667    if (fb->_ColorReadBufferIndex == -1 ||
 668        fb->DeletePending ||
 669        fb->Width == 0 ||
 670        fb->Height == 0) {
 671       fb->_ColorReadBuffer = NULL; /* legal! */
 672    }
 673    else {
 674       ASSERT(fb->_ColorReadBufferIndex >= 0);
 675       ASSERT(fb->_ColorReadBufferIndex < BUFFER_COUNT);
 676       fb->_ColorReadBuffer
 677          = fb->Attachment[fb->_ColorReadBufferIndex].Renderbuffer;
 678    }
 679 }
 680
 681
 682 /**
 683  * Update a gl_framebuffer's derived state.
 684  *
 685  * Specifically, update these framebuffer fields:
 686  *    _ColorDrawBuffers
 687  *    _NumColorDrawBuffers
 688  *    _ColorReadBuffer
 689  *    _DepthBuffer
 690  *    _StencilBuffer
 691  *
 692  * If the framebuffer is user-created, make sure it's complete.
 693  *
 694  * The following functions (at least) can effect framebuffer state:
 695  * glReadBuffer, glDrawBuffer, glDrawBuffersARB, glFramebufferRenderbufferEXT,
 696  * glRenderbufferStorageEXT.
 697  */
 698 static void
 699 update_framebuffer(GLcontext *ctx, struct gl_framebuffer *fb)
 700 {
 701    if (fb->Name == 0) {
 702       /* This is a window-system framebuffer */
 703       /* Need to update the FB's GL_DRAW_BUFFER state to match the
 704        * context state (GL_READ_BUFFER too).
 705        */
 706       if (fb->ColorDrawBuffer[0] != ctx->Color.DrawBuffer[0]) {
 707          _mesa_drawbuffers(ctx, ctx->Const.MaxDrawBuffers,
 708                            ctx->Color.DrawBuffer, NULL);
 709       }
 710       if (fb->ColorReadBuffer != ctx->Pixel.ReadBuffer) {
 711
 712       }
 713    }
 714    else {
 715       /* This is a user-created framebuffer.
 716        * Completeness only matters for user-created framebuffers.
 717        */
 718       _mesa_test_framebuffer_completeness(ctx, fb);
 719       _mesa_update_framebuffer_visual(fb);
 720    }
 721
 722    /* Strictly speaking, we don't need to update the draw-state
 723     * if this FB is bound as ctx->ReadBuffer (and conversely, the
 724     * read-state if this FB is bound as ctx->DrawBuffer), but no
 725     * harm.
 726     */
 727    update_color_draw_buffers(ctx, fb);
 728    update_color_read_buffer(ctx, fb);
 729    _mesa_update_depth_buffer(ctx, fb, BUFFER_DEPTH);
 730    _mesa_update_stencil_buffer(ctx, fb, BUFFER_STENCIL);
 731
 732    compute_depth_max(fb);
 733 }
 734
 735
 736 /**
 737  * Update state related to the current draw/read framebuffers.
 738  */
 739 void
 740 _mesa_update_framebuffer(GLcontext *ctx)
 741 {
 742    struct gl_framebuffer *drawFb = ctx->DrawBuffer;
 743    struct gl_framebuffer *readFb = ctx->ReadBuffer;
 744
 745    update_framebuffer(ctx, drawFb);
 746    if (readFb != drawFb)
 747       update_framebuffer(ctx, readFb);
 748 }
 749
 750
 751 /**
 752  * Check if the renderbuffer for a read operation (glReadPixels, glCopyPixels,
 753  * glCopyTex[Sub]Image, etc. exists.
 754  * \param format  a basic image format such as GL_RGB, GL_RGBA, GL_ALPHA,
 755  *                GL_DEPTH_COMPONENT, etc. or GL_COLOR, GL_DEPTH, GL_STENCIL.
 756  * \return GL_TRUE if buffer exists, GL_FALSE otherwise
 757  */
 758 GLboolean
 759 _mesa_source_buffer_exists(GLcontext *ctx, GLenum format)
 760 {
 761    const struct gl_renderbuffer_attachment *att
 762       = ctx->ReadBuffer->Attachment;
 763
 764    if (ctx->ReadBuffer->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
 765       return GL_FALSE;
 766    }
 767
 768    switch (format) {
 769    case GL_COLOR:
 770    case GL_RED:
 771    case GL_GREEN:
 772    case GL_BLUE:
 773    case GL_ALPHA:
 774    case GL_LUMINANCE:
 775    case GL_LUMINANCE_ALPHA:
 776    case GL_INTENSITY:
 777    case GL_RGB:
 778    case GL_BGR:
 779    case GL_RGBA:
 780    case GL_BGRA:
 781    case GL_ABGR_EXT:
 782    case GL_COLOR_INDEX:
 783       if (ctx->ReadBuffer->_ColorReadBuffer == NULL) {
 784          return GL_FALSE;
 785       }
 786       /* XXX enable this post 6.5 release:
 787       ASSERT(ctx->ReadBuffer->_ColorReadBuffer->RedBits > 0 ||
 788              ctx->ReadBuffer->_ColorReadBuffer->IndexBits > 0);
 789       */
 790       break;
 791    case GL_DEPTH:
 792    case GL_DEPTH_COMPONENT:
 793       if (!att[BUFFER_DEPTH].Renderbuffer) {
 794          return GL_FALSE;
 795       }
 796       ASSERT(att[BUFFER_DEPTH].Renderbuffer->DepthBits > 0);
 797       break;
 798    case GL_STENCIL:
 799    case GL_STENCIL_INDEX:
 800       if (!att[BUFFER_STENCIL].Renderbuffer) {
 801          return GL_FALSE;
 802       }
 803       ASSERT(att[BUFFER_STENCIL].Renderbuffer->StencilBits > 0);
 804       break;
 805    case GL_DEPTH_STENCIL_EXT:
 806       if (!att[BUFFER_DEPTH].Renderbuffer ||
 807           !att[BUFFER_STENCIL].Renderbuffer) {
 808          return GL_FALSE;
 809       }
 810       ASSERT(att[BUFFER_DEPTH].Renderbuffer->DepthBits > 0);
 811       ASSERT(att[BUFFER_STENCIL].Renderbuffer->StencilBits > 0);
 812       break;
 813    default:
 814       _mesa_problem(ctx,
 815                     "Unexpected format 0x%x in _mesa_source_buffer_exists",
 816                     format);
 817       return GL_FALSE;
 818    }
 819
 820    /* OK */
 821    return GL_TRUE;
 822 }
 823
 824
 825 /**
 826  * As above, but for drawing operations.
 827  * XXX code do some code merging w/ above function.
 828  */
 829 GLboolean
 830 _mesa_dest_buffer_exists(GLcontext *ctx, GLenum format)
 831 {
 832    const struct gl_renderbuffer_attachment *att
 833       = ctx->ReadBuffer->Attachment;
 834
 835    if (ctx->DrawBuffer->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
 836       return GL_FALSE;
 837    }
 838
 839    switch (format) {
 840    case GL_COLOR:
 841    case GL_RED:
 842    case GL_GREEN:
 843    case GL_BLUE:
 844    case GL_ALPHA:
 845    case GL_LUMINANCE:
 846    case GL_LUMINANCE_ALPHA:
 847    case GL_INTENSITY:
 848    case GL_RGB:
 849    case GL_BGR:
 850    case GL_RGBA:
 851    case GL_BGRA:
 852    case GL_ABGR_EXT:
 853    case GL_COLOR_INDEX:
 854       /* nothing special */
 855       /* Could assert that colorbuffer has RedBits > 0 */
 856       break;
 857    case GL_DEPTH:
 858    case GL_DEPTH_COMPONENT:
 859       if (!att[BUFFER_DEPTH].Renderbuffer) {
 860          return GL_FALSE;
 861       }
 862       ASSERT(att[BUFFER_DEPTH].Renderbuffer->DepthBits > 0);
 863       break;
 864    case GL_STENCIL:
 865    case GL_STENCIL_INDEX:
 866       if (!att[BUFFER_STENCIL].Renderbuffer) {
 867          return GL_FALSE;
 868       }
 869       ASSERT(att[BUFFER_STENCIL].Renderbuffer->StencilBits > 0);
 870       break;
 871    case GL_DEPTH_STENCIL_EXT:
 872       if (!att[BUFFER_DEPTH].Renderbuffer ||
 873           !att[BUFFER_STENCIL].Renderbuffer) {
 874          return GL_FALSE;
 875       }
 876       ASSERT(att[BUFFER_DEPTH].Renderbuffer->DepthBits > 0);
 877       ASSERT(att[BUFFER_STENCIL].Renderbuffer->StencilBits > 0);
 878       break;
 879    default:
 880       _mesa_problem(ctx,
 881                     "Unexpected format 0x%x in _mesa_source_buffer_exists",
 882                     format);
 883       return GL_FALSE;
 884    }
 885
 886    /* OK */
 887    return GL_TRUE;
 888 }