src/mesa/main/framebuffer.c

   1 /*
   2  * Mesa 3-D graphics library
   3  * Version:  7.2
   4  *
   5  * Copyright (C) 1999-2008  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 "enums.h"
  38 #include "formats.h"
  39 #include "macros.h"
  40 #include "mtypes.h"
  41 #include "fbobject.h"
  42 #include "framebuffer.h"
  43 #include "renderbuffer.h"
  44 #include "texobj.h"
  45
  46
  47
  48 /**
  49  * Compute/set the _DepthMax field for the given framebuffer.
  50  * This value depends on the Z buffer resolution.
  51  */
  52 static void
  53 compute_depth_max(struct gl_framebuffer *fb)
  54 {
  55    if (fb->Visual.depthBits == 0) {
  56       /* Special case.  Even if we don't have a depth buffer we need
  57        * good values for DepthMax for Z vertex transformation purposes
  58        * and for per-fragment fog computation.
  59        */
  60       fb->_DepthMax = (1 << 16) - 1;
  61    }
  62    else if (fb->Visual.depthBits < 32) {
  63       fb->_DepthMax = (1 << fb->Visual.depthBits) - 1;
  64    }
  65    else {
  66       /* Special case since shift values greater than or equal to the
  67        * number of bits in the left hand expression's type are undefined.
  68        */
  69       fb->_DepthMax = 0xffffffff;
  70    }
  71    fb->_DepthMaxF = (GLfloat) fb->_DepthMax;
  72
  73    /* Minimum resolvable depth value, for polygon offset */
  74    fb->_MRD = (GLfloat)1.0 / fb->_DepthMaxF;
  75 }
  76
  77 /**
  78  * Create and initialize a gl_framebuffer object.
  79  * This is intended for creating _window_system_ framebuffers, not generic
  80  * framebuffer objects ala GL_EXT_framebuffer_object.
  81  *
  82  * \sa _mesa_new_framebuffer
  83  */
  84 struct gl_framebuffer *
  85 _mesa_create_framebuffer(const struct gl_config *visual)
  86 {
  87    struct gl_framebuffer *fb = CALLOC_STRUCT(gl_framebuffer);
  88    assert(visual);
  89    if (fb) {
  90       _mesa_initialize_window_framebuffer(fb, visual);
  91    }
  92    return fb;
  93 }
  94
  95
  96 /**
  97  * Allocate a new gl_framebuffer object.
  98  * This is the default function for ctx->Driver.NewFramebuffer().
  99  * This is for allocating user-created framebuffers, not window-system
 100  * framebuffers!
 101  * \sa _mesa_create_framebuffer
 102  */
 103 struct gl_framebuffer *
 104 _mesa_new_framebuffer(struct gl_context *ctx, GLuint name)
 105 {
 106    struct gl_framebuffer *fb;
 107    (void) ctx;
 108    assert(name != 0);
 109    fb = CALLOC_STRUCT(gl_framebuffer);
 110    if (fb) {
 111       _mesa_initialize_user_framebuffer(fb, name);
 112    }
 113    return fb;
 114 }
 115
 116
 117 /**
 118  * Initialize a gl_framebuffer object.  Typically used to initialize
 119  * window system-created framebuffers, not user-created framebuffers.
 120  * \sa _mesa_initialize_user_framebuffer
 121  */
 122 void
 123 _mesa_initialize_window_framebuffer(struct gl_framebuffer *fb,
 124                                      const struct gl_config *visual)
 125 {
 126    assert(fb);
 127    assert(visual);
 128
 129    memset(fb, 0, sizeof(struct gl_framebuffer));
 130
 131    _glthread_INIT_MUTEX(fb->Mutex);
 132
 133    fb->RefCount = 1;
 134
 135    /* save the visual */
 136    fb->Visual = *visual;
 137
 138    /* Init read/draw renderbuffer state */
 139    if (visual->doubleBufferMode) {
 140       fb->_NumColorDrawBuffers = 1;
 141       fb->ColorDrawBuffer[0] = GL_BACK;
 142       fb->_ColorDrawBufferIndexes[0] = BUFFER_BACK_LEFT;
 143       fb->ColorReadBuffer = GL_BACK;
 144       fb->_ColorReadBufferIndex = BUFFER_BACK_LEFT;
 145    }
 146    else {
 147       fb->_NumColorDrawBuffers = 1;
 148       fb->ColorDrawBuffer[0] = GL_FRONT;
 149       fb->_ColorDrawBufferIndexes[0] = BUFFER_FRONT_LEFT;
 150       fb->ColorReadBuffer = GL_FRONT;
 151       fb->_ColorReadBufferIndex = BUFFER_FRONT_LEFT;
 152    }
 153
 154    fb->Delete = _mesa_destroy_framebuffer;
 155    fb->_Status = GL_FRAMEBUFFER_COMPLETE_EXT;
 156
 157    compute_depth_max(fb);
 158 }
 159
 160
 161 /**
 162  * Initialize a user-created gl_framebuffer object.
 163  * \sa _mesa_initialize_window_framebuffer
 164  */
 165 void
 166 _mesa_initialize_user_framebuffer(struct gl_framebuffer *fb, GLuint name)
 167 {
 168    assert(fb);
 169    assert(name);
 170
 171    memset(fb, 0, sizeof(struct gl_framebuffer));
 172
 173    fb->Name = name;
 174    fb->RefCount = 1;
 175    fb->_NumColorDrawBuffers = 1;
 176    fb->ColorDrawBuffer[0] = GL_COLOR_ATTACHMENT0_EXT;
 177    fb->_ColorDrawBufferIndexes[0] = BUFFER_COLOR0;
 178    fb->ColorReadBuffer = GL_COLOR_ATTACHMENT0_EXT;
 179    fb->_ColorReadBufferIndex = BUFFER_COLOR0;
 180    fb->Delete = _mesa_destroy_framebuffer;
 181    _glthread_INIT_MUTEX(fb->Mutex);
 182 }
 183
 184
 185 /**
 186  * Deallocate buffer and everything attached to it.
 187  * Typically called via the gl_framebuffer->Delete() method.
 188  */
 189 void
 190 _mesa_destroy_framebuffer(struct gl_framebuffer *fb)
 191 {
 192    if (fb) {
 193       _mesa_free_framebuffer_data(fb);
 194       free(fb);
 195    }
 196 }
 197
 198
 199 /**
 200  * Free all the data hanging off the given gl_framebuffer, but don't free
 201  * the gl_framebuffer object itself.
 202  */
 203 void
 204 _mesa_free_framebuffer_data(struct gl_framebuffer *fb)
 205 {
 206    GLuint i;
 207
 208    assert(fb);
 209    assert(fb->RefCount == 0);
 210
 211    _glthread_DESTROY_MUTEX(fb->Mutex);
 212
 213    for (i = 0; i < BUFFER_COUNT; i++) {
 214       struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
 215       if (att->Renderbuffer) {
 216          _mesa_reference_renderbuffer(&att->Renderbuffer, NULL);
 217       }
 218       if (att->Texture) {
 219          _mesa_reference_texobj(&att->Texture, NULL);
 220       }
 221       ASSERT(!att->Renderbuffer);
 222       ASSERT(!att->Texture);
 223       att->Type = GL_NONE;
 224    }
 225
 226    /* unbind _Depth/_StencilBuffer to decr ref counts */
 227    _mesa_reference_renderbuffer(&fb->_DepthBuffer, NULL);
 228    _mesa_reference_renderbuffer(&fb->_StencilBuffer, NULL);
 229 }
 230
 231
 232 /**
 233  * Set *ptr to point to fb, with refcounting and locking.
 234  * This is normally only called from the _mesa_reference_framebuffer() macro
 235  * when there's a real pointer change.
 236  */
 237 void
 238 _mesa_reference_framebuffer_(struct gl_framebuffer **ptr,
 239                              struct gl_framebuffer *fb)
 240 {
 241    if (*ptr) {
 242       /* unreference old renderbuffer */
 243       GLboolean deleteFlag = GL_FALSE;
 244       struct gl_framebuffer *oldFb = *ptr;
 245
 246       _glthread_LOCK_MUTEX(oldFb->Mutex);
 247       ASSERT(oldFb->RefCount > 0);
 248       oldFb->RefCount--;
 249       deleteFlag = (oldFb->RefCount == 0);
 250       _glthread_UNLOCK_MUTEX(oldFb->Mutex);
 251
 252       if (deleteFlag)
 253          oldFb->Delete(oldFb);
 254
 255       *ptr = NULL;
 256    }
 257    assert(!*ptr);
 258
 259    if (fb) {
 260       _glthread_LOCK_MUTEX(fb->Mutex);
 261       fb->RefCount++;
 262       _glthread_UNLOCK_MUTEX(fb->Mutex);
 263       *ptr = fb;
 264    }
 265 }
 266
 267
 268 /**
 269  * Resize the given framebuffer's renderbuffers to the new width and height.
 270  * This should only be used for window-system framebuffers, not
 271  * user-created renderbuffers (i.e. made with GL_EXT_framebuffer_object).
 272  * This will typically be called via ctx->Driver.ResizeBuffers() or directly
 273  * from a device driver.
 274  *
 275  * \note it's possible for ctx to be null since a window can be resized
 276  * without a currently bound rendering context.
 277  */
 278 void
 279 _mesa_resize_framebuffer(struct gl_context *ctx, struct gl_framebuffer *fb,
 280                          GLuint width, GLuint height)
 281 {
 282    GLuint i;
 283
 284    /* XXX I think we could check if the size is not changing
 285     * and return early.
 286     */
 287
 288    /* For window system framebuffers, Name is zero */
 289    assert(fb->Name == 0);
 290
 291    for (i = 0; i < BUFFER_COUNT; i++) {
 292       struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
 293       if (att->Type == GL_RENDERBUFFER_EXT && att->Renderbuffer) {
 294          struct gl_renderbuffer *rb = att->Renderbuffer;
 295          /* only resize if size is changing */
 296          if (rb->Width != width || rb->Height != height) {
 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 /**
 343  * XXX THIS IS OBSOLETE - drivers should take care of detecting window
 344  * size changes and act accordingly, likely calling _mesa_resize_framebuffer().
 345  *
 346  * GL_MESA_resize_buffers extension.
 347  *
 348  * When this function is called, we'll ask the window system how large
 349  * the current window is.  If it's a new size, we'll call the driver's
 350  * ResizeBuffers function.  The driver will then resize its color buffers
 351  * as needed, and maybe call the swrast's routine for reallocating
 352  * swrast-managed depth/stencil/accum/etc buffers.
 353  * \note This function should only be called through the GL API, not
 354  * from device drivers (as was done in the past).
 355  */
 356 void
 357 _mesa_resizebuffers( struct gl_context *ctx )
 358 {
 359    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH( ctx );
 360
 361    if (MESA_VERBOSE & VERBOSE_API)
 362       _mesa_debug(ctx, "glResizeBuffersMESA\n");
 363
 364    if (!ctx->Driver.GetBufferSize) {
 365       return;
 366    }
 367
 368    if (ctx->WinSysDrawBuffer) {
 369       GLuint newWidth, newHeight;
 370       struct gl_framebuffer *buffer = ctx->WinSysDrawBuffer;
 371
 372       assert(buffer->Name == 0);
 373
 374       /* ask device driver for size of output buffer */
 375       ctx->Driver.GetBufferSize( buffer, &newWidth, &newHeight );
 376
 377       /* see if size of device driver's color buffer (window) has changed */
 378       if (buffer->Width != newWidth || buffer->Height != newHeight) {
 379          if (ctx->Driver.ResizeBuffers)
 380             ctx->Driver.ResizeBuffers(ctx, buffer, newWidth, newHeight );
 381       }
 382    }
 383
 384    if (ctx->WinSysReadBuffer
 385        && ctx->WinSysReadBuffer != ctx->WinSysDrawBuffer) {
 386       GLuint newWidth, newHeight;
 387       struct gl_framebuffer *buffer = ctx->WinSysReadBuffer;
 388
 389       assert(buffer->Name == 0);
 390
 391       /* ask device driver for size of read buffer */
 392       ctx->Driver.GetBufferSize( buffer, &newWidth, &newHeight );
 393
 394       /* see if size of device driver's color buffer (window) has changed */
 395       if (buffer->Width != newWidth || buffer->Height != newHeight) {
 396          if (ctx->Driver.ResizeBuffers)
 397             ctx->Driver.ResizeBuffers(ctx, buffer, newWidth, newHeight );
 398       }
 399    }
 400
 401    ctx->NewState |= _NEW_BUFFERS;  /* to update scissor / window bounds */
 402 }
 403
 404
 405 /*
 406  * XXX THIS IS OBSOLETE
 407  */
 408 void GLAPIENTRY
 409 _mesa_ResizeBuffersMESA( void )
 410 {
 411    GET_CURRENT_CONTEXT(ctx);
 412
 413    if (ctx->Extensions.MESA_resize_buffers)
 414       _mesa_resizebuffers( ctx );
 415 }
 416
 417
 418
 419 /**
 420  * Examine all the framebuffer's renderbuffers to update the Width/Height
 421  * fields of the framebuffer.  If we have renderbuffers with different
 422  * sizes, set the framebuffer's width and height to the min size.
 423  * Note: this is only intended for user-created framebuffers, not
 424  * window-system framebuffes.
 425  */
 426 static void
 427 update_framebuffer_size(struct gl_context *ctx, struct gl_framebuffer *fb)
 428 {
 429    GLuint minWidth = ~0, minHeight = ~0;
 430    GLuint i;
 431
 432    /* user-created framebuffers only */
 433    assert(fb->Name);
 434
 435    for (i = 0; i < BUFFER_COUNT; i++) {
 436       struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
 437       const struct gl_renderbuffer *rb = att->Renderbuffer;
 438       if (rb) {
 439          minWidth = MIN2(minWidth, rb->Width);
 440          minHeight = MIN2(minHeight, rb->Height);
 441       }
 442    }
 443
 444    if (minWidth != ~0) {
 445       fb->Width = minWidth;
 446       fb->Height = minHeight;
 447    }
 448    else {
 449       fb->Width = 0;
 450       fb->Height = 0;
 451    }
 452 }
 453
 454
 455 /**
 456  * Update the context's current drawing buffer's Xmin, Xmax, Ymin, Ymax fields.
 457  * These values are computed from the buffer's width and height and
 458  * the scissor box, if it's enabled.
 459  * \param ctx  the GL context.
 460  */
 461 void
 462 _mesa_update_draw_buffer_bounds(struct gl_context *ctx)
 463 {
 464    struct gl_framebuffer *buffer = ctx->DrawBuffer;
 465
 466    if (!buffer)
 467       return;
 468
 469    if (buffer->Name) {
 470       /* user-created framebuffer size depends on the renderbuffers */
 471       update_framebuffer_size(ctx, buffer);
 472    }
 473
 474    buffer->_Xmin = 0;
 475    buffer->_Ymin = 0;
 476    buffer->_Xmax = buffer->Width;
 477    buffer->_Ymax = buffer->Height;
 478
 479    if (ctx->Scissor.Enabled) {
 480       if (ctx->Scissor.X > buffer->_Xmin) {
 481          buffer->_Xmin = ctx->Scissor.X;
 482       }
 483       if (ctx->Scissor.Y > buffer->_Ymin) {
 484          buffer->_Ymin = ctx->Scissor.Y;
 485       }
 486       if (ctx->Scissor.X + ctx->Scissor.Width < buffer->_Xmax) {
 487          buffer->_Xmax = ctx->Scissor.X + ctx->Scissor.Width;
 488       }
 489       if (ctx->Scissor.Y + ctx->Scissor.Height < buffer->_Ymax) {
 490          buffer->_Ymax = ctx->Scissor.Y + ctx->Scissor.Height;
 491       }
 492       /* finally, check for empty region */
 493       if (buffer->_Xmin > buffer->_Xmax) {
 494          buffer->_Xmin = buffer->_Xmax;
 495       }
 496       if (buffer->_Ymin > buffer->_Ymax) {
 497          buffer->_Ymin = buffer->_Ymax;
 498       }
 499    }
 500
 501    ASSERT(buffer->_Xmin <= buffer->_Xmax);
 502    ASSERT(buffer->_Ymin <= buffer->_Ymax);
 503 }
 504
 505
 506 /**
 507  * The glGet queries of the framebuffer red/green/blue size, stencil size,
 508  * etc. are satisfied by the fields of ctx->DrawBuffer->Visual.  These can
 509  * change depending on the renderbuffer bindings.  This function updates
 510  * the given framebuffer's Visual from the current renderbuffer bindings.
 511  *
 512  * This may apply to user-created framebuffers or window system framebuffers.
 513  *
 514  * Also note: ctx->DrawBuffer->Visual.depthBits might not equal
 515  * ctx->DrawBuffer->Attachment[BUFFER_DEPTH].Renderbuffer.DepthBits.
 516  * The former one is used to convert floating point depth values into
 517  * integer Z values.
 518  */
 519 void
 520 _mesa_update_framebuffer_visual(struct gl_context *ctx,
 521                                 struct gl_framebuffer *fb)
 522 {
 523    GLuint i;
 524
 525    memset(&fb->Visual, 0, sizeof(fb->Visual));
 526    fb->Visual.rgbMode = GL_TRUE; /* assume this */
 527
 528 #if 0 /* this _might_ be needed */
 529    if (fb->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
 530       /* leave visual fields zero'd */
 531       return;
 532    }
 533 #endif
 534
 535    /* find first RGB renderbuffer */
 536    for (i = 0; i < BUFFER_COUNT; i++) {
 537       if (fb->Attachment[i].Renderbuffer) {
 538          const struct gl_renderbuffer *rb = fb->Attachment[i].Renderbuffer;
 539          const GLenum baseFormat = _mesa_get_format_base_format(rb->Format);
 540          const gl_format fmt = rb->Format;
 541
 542          if (_mesa_is_legal_color_format(ctx, baseFormat)) {
 543             fb->Visual.redBits = _mesa_get_format_bits(fmt, GL_RED_BITS);
 544             fb->Visual.greenBits = _mesa_get_format_bits(fmt, GL_GREEN_BITS);
 545             fb->Visual.blueBits = _mesa_get_format_bits(fmt, GL_BLUE_BITS);
 546             fb->Visual.alphaBits = _mesa_get_format_bits(fmt, GL_ALPHA_BITS);
 547             fb->Visual.rgbBits = fb->Visual.redBits
 548                + fb->Visual.greenBits + fb->Visual.blueBits;
 549             fb->Visual.samples = rb->NumSamples;
 550             fb->Visual.sampleBuffers = rb->NumSamples > 0 ? 1 : 0;
 551             if (_mesa_get_format_color_encoding(fmt) == GL_SRGB)
 552                 fb->Visual.sRGBCapable = ctx->Const.sRGBCapable;
 553             break;
 554          }
 555       }
 556    }
 557
 558    fb->Visual.floatMode = GL_FALSE;
 559    for (i = 0; i < BUFFER_COUNT; i++) {
 560       if (fb->Attachment[i].Renderbuffer) {
 561          const struct gl_renderbuffer *rb = fb->Attachment[i].Renderbuffer;
 562          const gl_format fmt = rb->Format;
 563
 564          if (_mesa_get_format_datatype(fmt) == GL_FLOAT) {
 565             fb->Visual.floatMode = GL_TRUE;
 566             break;
 567          }
 568       }
 569    }
 570
 571    if (fb->Attachment[BUFFER_DEPTH].Renderbuffer) {
 572       const struct gl_renderbuffer *rb =
 573          fb->Attachment[BUFFER_DEPTH].Renderbuffer;
 574       const gl_format fmt = rb->Format;
 575       fb->Visual.haveDepthBuffer = GL_TRUE;
 576       fb->Visual.depthBits = _mesa_get_format_bits(fmt, GL_DEPTH_BITS);
 577    }
 578
 579    if (fb->Attachment[BUFFER_STENCIL].Renderbuffer) {
 580       const struct gl_renderbuffer *rb =
 581          fb->Attachment[BUFFER_STENCIL].Renderbuffer;
 582       const gl_format fmt = rb->Format;
 583       fb->Visual.haveStencilBuffer = GL_TRUE;
 584       fb->Visual.stencilBits = _mesa_get_format_bits(fmt, GL_STENCIL_BITS);
 585    }
 586
 587    if (fb->Attachment[BUFFER_ACCUM].Renderbuffer) {
 588       const struct gl_renderbuffer *rb =
 589          fb->Attachment[BUFFER_ACCUM].Renderbuffer;
 590       const gl_format fmt = rb->Format;
 591       fb->Visual.haveAccumBuffer = GL_TRUE;
 592       fb->Visual.accumRedBits = _mesa_get_format_bits(fmt, GL_RED_BITS);
 593       fb->Visual.accumGreenBits = _mesa_get_format_bits(fmt, GL_GREEN_BITS);
 594       fb->Visual.accumBlueBits = _mesa_get_format_bits(fmt, GL_BLUE_BITS);
 595       fb->Visual.accumAlphaBits = _mesa_get_format_bits(fmt, GL_ALPHA_BITS);
 596    }
 597
 598    compute_depth_max(fb);
 599 }
 600
 601
 602 /*
 603  * Example DrawBuffers scenarios:
 604  *
 605  * 1. glDrawBuffer(GL_FRONT_AND_BACK), fixed-func or shader writes to
 606  * "gl_FragColor" or program writes to the "result.color" register:
 607  *
 608  *   fragment color output   renderbuffer
 609  *   ---------------------   ---------------
 610  *   color[0]                Front, Back
 611  *
 612  *
 613  * 2. glDrawBuffers(3, [GL_FRONT, GL_AUX0, GL_AUX1]), shader writes to
 614  * gl_FragData[i] or program writes to result.color[i] registers:
 615  *
 616  *   fragment color output   renderbuffer
 617  *   ---------------------   ---------------
 618  *   color[0]                Front
 619  *   color[1]                Aux0
 620  *   color[3]                Aux1
 621  *
 622  *
 623  * 3. glDrawBuffers(3, [GL_FRONT, GL_AUX0, GL_AUX1]) and shader writes to
 624  * gl_FragColor, or fixed function:
 625  *
 626  *   fragment color output   renderbuffer
 627  *   ---------------------   ---------------
 628  *   color[0]                Front, Aux0, Aux1
 629  *
 630  *
 631  * In either case, the list of renderbuffers is stored in the
 632  * framebuffer->_ColorDrawBuffers[] array and
 633  * framebuffer->_NumColorDrawBuffers indicates the number of buffers.
 634  * The renderer (like swrast) has to look at the current fragment shader
 635  * to see if it writes to gl_FragColor vs. gl_FragData[i] to determine
 636  * how to map color outputs to renderbuffers.
 637  *
 638  * Note that these two calls are equivalent (for fixed function fragment
 639  * shading anyway):
 640  *   a)  glDrawBuffer(GL_FRONT_AND_BACK);  (assuming non-stereo framebuffer)
 641  *   b)  glDrawBuffers(2, [GL_FRONT_LEFT, GL_BACK_LEFT]);
 642  */
 643
 644
 645
 646
 647 /**
 648  * Update the (derived) list of color drawing renderbuffer pointers.
 649  * Later, when we're rendering we'll loop from 0 to _NumColorDrawBuffers
 650  * writing colors.
 651  */
 652 static void
 653 update_color_draw_buffers(struct gl_context *ctx, struct gl_framebuffer *fb)
 654 {
 655    GLuint output;
 656
 657    /* set 0th buffer to NULL now in case _NumColorDrawBuffers is zero */
 658    fb->_ColorDrawBuffers[0] = NULL;
 659
 660    for (output = 0; output < fb->_NumColorDrawBuffers; output++) {
 661       GLint buf = fb->_ColorDrawBufferIndexes[output];
 662       if (buf >= 0) {
 663          fb->_ColorDrawBuffers[output] = fb->Attachment[buf].Renderbuffer;
 664       }
 665       else {
 666          fb->_ColorDrawBuffers[output] = NULL;
 667       }
 668    }
 669 }
 670
 671
 672 /**
 673  * Update the (derived) color read renderbuffer pointer.
 674  * Unlike the DrawBuffer, we can only read from one (or zero) color buffers.
 675  */
 676 static void
 677 update_color_read_buffer(struct gl_context *ctx, struct gl_framebuffer *fb)
 678 {
 679    (void) ctx;
 680    if (fb->_ColorReadBufferIndex == -1 ||
 681        fb->DeletePending ||
 682        fb->Width == 0 ||
 683        fb->Height == 0) {
 684       fb->_ColorReadBuffer = NULL; /* legal! */
 685    }
 686    else {
 687       ASSERT(fb->_ColorReadBufferIndex >= 0);
 688       ASSERT(fb->_ColorReadBufferIndex < BUFFER_COUNT);
 689       fb->_ColorReadBuffer
 690          = fb->Attachment[fb->_ColorReadBufferIndex].Renderbuffer;
 691    }
 692 }
 693
 694
 695 /**
 696  * Update a gl_framebuffer's derived state.
 697  *
 698  * Specifically, update these framebuffer fields:
 699  *    _ColorDrawBuffers
 700  *    _NumColorDrawBuffers
 701  *    _ColorReadBuffer
 702  *    _DepthBuffer
 703  *    _StencilBuffer
 704  *
 705  * If the framebuffer is user-created, make sure it's complete.
 706  *
 707  * The following functions (at least) can effect framebuffer state:
 708  * glReadBuffer, glDrawBuffer, glDrawBuffersARB, glFramebufferRenderbufferEXT,
 709  * glRenderbufferStorageEXT.
 710  */
 711 static void
 712 update_framebuffer(struct gl_context *ctx, struct gl_framebuffer *fb)
 713 {
 714    if (fb->Name == 0) {
 715       /* This is a window-system framebuffer */
 716       /* Need to update the FB's GL_DRAW_BUFFER state to match the
 717        * context state (GL_READ_BUFFER too).
 718        */
 719       if (fb->ColorDrawBuffer[0] != ctx->Color.DrawBuffer[0]) {
 720          _mesa_drawbuffers(ctx, ctx->Const.MaxDrawBuffers,
 721                            ctx->Color.DrawBuffer, NULL);
 722       }
 723    }
 724    else {
 725       /* This is a user-created framebuffer.
 726        * Completeness only matters for user-created framebuffers.
 727        */
 728       if (fb->_Status != GL_FRAMEBUFFER_COMPLETE) {
 729          _mesa_test_framebuffer_completeness(ctx, fb);
 730       }
 731    }
 732
 733    /* Strictly speaking, we don't need to update the draw-state
 734     * if this FB is bound as ctx->ReadBuffer (and conversely, the
 735     * read-state if this FB is bound as ctx->DrawBuffer), but no
 736     * harm.
 737     */
 738    update_color_draw_buffers(ctx, fb);
 739    update_color_read_buffer(ctx, fb);
 740
 741    compute_depth_max(fb);
 742 }
 743
 744
 745 /**
 746  * Update state related to the current draw/read framebuffers.
 747  */
 748 void
 749 _mesa_update_framebuffer(struct gl_context *ctx)
 750 {
 751    struct gl_framebuffer *drawFb;
 752    struct gl_framebuffer *readFb;
 753
 754    assert(ctx);
 755    drawFb = ctx->DrawBuffer;
 756    readFb = ctx->ReadBuffer;
 757
 758    update_framebuffer(ctx, drawFb);
 759    if (readFb != drawFb)
 760       update_framebuffer(ctx, readFb);
 761 }
 762
 763
 764 /**
 765  * Check if the renderbuffer for a read/draw operation exists.
 766  * \param format  a basic image format such as GL_RGB, GL_RGBA, GL_ALPHA,
 767  *                GL_DEPTH_COMPONENT, etc. or GL_COLOR, GL_DEPTH, GL_STENCIL.
 768  * \param reading  if TRUE, we're going to read from the buffer,
 769                    if FALSE, we're going to write to the buffer.
 770  * \return GL_TRUE if buffer exists, GL_FALSE otherwise
 771  */
 772 static GLboolean
 773 renderbuffer_exists(struct gl_context *ctx,
 774                     struct gl_framebuffer *fb,
 775                     GLenum format,
 776                     GLboolean reading)
 777 {
 778    const struct gl_renderbuffer_attachment *att = fb->Attachment;
 779
 780    /* If we don't know the framebuffer status, update it now */
 781    if (fb->_Status == 0) {
 782       _mesa_test_framebuffer_completeness(ctx, fb);
 783    }
 784
 785    if (fb->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
 786       return GL_FALSE;
 787    }
 788
 789    switch (format) {
 790    case GL_COLOR:
 791    case GL_RED:
 792    case GL_GREEN:
 793    case GL_BLUE:
 794    case GL_ALPHA:
 795    case GL_LUMINANCE:
 796    case GL_LUMINANCE_ALPHA:
 797    case GL_INTENSITY:
 798    case GL_RG:
 799    case GL_RGB:
 800    case GL_BGR:
 801    case GL_RGBA:
 802    case GL_BGRA:
 803    case GL_ABGR_EXT:
 804    case GL_RED_INTEGER_EXT:
 805    case GL_RG_INTEGER:
 806    case GL_GREEN_INTEGER_EXT:
 807    case GL_BLUE_INTEGER_EXT:
 808    case GL_ALPHA_INTEGER_EXT:
 809    case GL_RGB_INTEGER_EXT:
 810    case GL_RGBA_INTEGER_EXT:
 811    case GL_BGR_INTEGER_EXT:
 812    case GL_BGRA_INTEGER_EXT:
 813    case GL_LUMINANCE_INTEGER_EXT:
 814    case GL_LUMINANCE_ALPHA_INTEGER_EXT:
 815       if (reading) {
 816          /* about to read from a color buffer */
 817          const struct gl_renderbuffer *readBuf = fb->_ColorReadBuffer;
 818          if (!readBuf) {
 819             return GL_FALSE;
 820          }
 821          ASSERT(_mesa_get_format_bits(readBuf->Format, GL_RED_BITS) > 0 ||
 822                 _mesa_get_format_bits(readBuf->Format, GL_ALPHA_BITS) > 0 ||
 823                 _mesa_get_format_bits(readBuf->Format, GL_TEXTURE_LUMINANCE_SIZE) > 0 ||
 824                 _mesa_get_format_bits(readBuf->Format, GL_TEXTURE_INTENSITY_SIZE) > 0 ||
 825                 _mesa_get_format_bits(readBuf->Format, GL_INDEX_BITS) > 0);
 826       }
 827       else {
 828          /* about to draw to zero or more color buffers (none is OK) */
 829          return GL_TRUE;
 830       }
 831       break;
 832    case GL_DEPTH:
 833    case GL_DEPTH_COMPONENT:
 834       if (att[BUFFER_DEPTH].Type == GL_NONE) {
 835          return GL_FALSE;
 836       }
 837       break;
 838    case GL_STENCIL:
 839    case GL_STENCIL_INDEX:
 840       if (att[BUFFER_STENCIL].Type == GL_NONE) {
 841          return GL_FALSE;
 842       }
 843       break;
 844    case GL_DEPTH_STENCIL_EXT:
 845       if (att[BUFFER_DEPTH].Type == GL_NONE ||
 846           att[BUFFER_STENCIL].Type == GL_NONE) {
 847          return GL_FALSE;
 848       }
 849       break;
 850    default:
 851       _mesa_problem(ctx,
 852                     "Unexpected format 0x%x in renderbuffer_exists",
 853                     format);
 854       return GL_FALSE;
 855    }
 856
 857    /* OK */
 858    return GL_TRUE;
 859 }
 860
 861
 862 /**
 863  * Check if the renderbuffer for a read operation (glReadPixels, glCopyPixels,
 864  * glCopyTex[Sub]Image, etc) exists.
 865  * \param format  a basic image format such as GL_RGB, GL_RGBA, GL_ALPHA,
 866  *                GL_DEPTH_COMPONENT, etc. or GL_COLOR, GL_DEPTH, GL_STENCIL.
 867  * \return GL_TRUE if buffer exists, GL_FALSE otherwise
 868  */
 869 GLboolean
 870 _mesa_source_buffer_exists(struct gl_context *ctx, GLenum format)
 871 {
 872    return renderbuffer_exists(ctx, ctx->ReadBuffer, format, GL_TRUE);
 873 }
 874
 875
 876 /**
 877  * As above, but for drawing operations.
 878  * XXX could do some code merging w/ above function.
 879  */
 880 GLboolean
 881 _mesa_dest_buffer_exists(struct gl_context *ctx, GLenum format)
 882 {
 883    return renderbuffer_exists(ctx, ctx->DrawBuffer, format, GL_FALSE);
 884 }
 885
 886
 887 /**
 888  * Used to answer the GL_IMPLEMENTATION_COLOR_READ_FORMAT_OES query.
 889  */
 890 GLenum
 891 _mesa_get_color_read_format(struct gl_context *ctx)
 892 {
 893    switch (ctx->ReadBuffer->_ColorReadBuffer->Format) {
 894    case MESA_FORMAT_ARGB8888:
 895       return GL_BGRA;
 896    case MESA_FORMAT_RGB565:
 897       return GL_BGR;
 898    default:
 899       return GL_RGBA;
 900    }
 901 }
 902
 903
 904 /**
 905  * Used to answer the GL_IMPLEMENTATION_COLOR_READ_TYPE_OES query.
 906  */
 907 GLenum
 908 _mesa_get_color_read_type(struct gl_context *ctx)
 909 {
 910    switch (ctx->ReadBuffer->_ColorReadBuffer->Format) {
 911    case MESA_FORMAT_ARGB8888:
 912       return GL_UNSIGNED_BYTE;
 913    case MESA_FORMAT_RGB565:
 914       return GL_UNSIGNED_SHORT_5_6_5_REV;
 915    default:
 916       return GL_UNSIGNED_BYTE;
 917    }
 918 }
 919
 920
 921 /**
 922  * Print framebuffer info to stderr, for debugging.
 923  */
 924 void
 925 _mesa_print_framebuffer(const struct gl_framebuffer *fb)
 926 {
 927    GLuint i;
 928
 929    fprintf(stderr, "Mesa Framebuffer %u at %p\n", fb->Name, (void *) fb);
 930    fprintf(stderr, "  Size: %u x %u  Status: %s\n", fb->Width, fb->Height,
 931            _mesa_lookup_enum_by_nr(fb->_Status));
 932    fprintf(stderr, "  Attachments:\n");
 933
 934    for (i = 0; i < BUFFER_COUNT; i++) {
 935       const struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
 936       if (att->Type == GL_TEXTURE) {
 937          const struct gl_texture_image *texImage =
 938             _mesa_get_attachment_teximage_const(att);
 939          fprintf(stderr,
 940                  "  %2d: Texture %u, level %u, face %u, slice %u, complete %d\n",
 941                  i, att->Texture->Name, att->TextureLevel, att->CubeMapFace,
 942                  att->Zoffset, att->Complete);
 943          fprintf(stderr, "       Size: %u x %u x %u  Format %s\n",
 944                  texImage->Width, texImage->Height, texImage->Depth,
 945                  _mesa_get_format_name(texImage->TexFormat));
 946       }
 947       else if (att->Type == GL_RENDERBUFFER) {
 948          fprintf(stderr, "  %2d: Renderbuffer %u, complete %d\n",
 949                  i, att->Renderbuffer->Name, att->Complete);
 950          fprintf(stderr, "       Size: %u x %u  Format %s\n",
 951                  att->Renderbuffer->Width, att->Renderbuffer->Height,
 952                  _mesa_get_format_name(att->Renderbuffer->Format));
 953       }
 954       else {
 955          fprintf(stderr, "  %2d: none\n", i);
 956       }
 957    }
 958 }