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 #include "glformats.h"
  46
  47
  48
  49 /**
  50  * Compute/set the _DepthMax field for the given framebuffer.
  51  * This value depends on the Z buffer resolution.
  52  */
  53 static void
  54 compute_depth_max(struct gl_framebuffer *fb)
  55 {
  56    if (fb->Visual.depthBits == 0) {
  57       /* Special case.  Even if we don't have a depth buffer we need
  58        * good values for DepthMax for Z vertex transformation purposes
  59        * and for per-fragment fog computation.
  60        */
  61       fb->_DepthMax = (1 << 16) - 1;
  62    }
  63    else if (fb->Visual.depthBits < 32) {
  64       fb->_DepthMax = (1 << fb->Visual.depthBits) - 1;
  65    }
  66    else {
  67       /* Special case since shift values greater than or equal to the
  68        * number of bits in the left hand expression's type are undefined.
  69        */
  70       fb->_DepthMax = 0xffffffff;
  71    }
  72    fb->_DepthMaxF = (GLfloat) fb->_DepthMax;
  73
  74    /* Minimum resolvable depth value, for polygon offset */
  75    fb->_MRD = (GLfloat)1.0 / fb->_DepthMaxF;
  76 }
  77
  78 /**
  79  * Create and initialize a gl_framebuffer object.
  80  * This is intended for creating _window_system_ framebuffers, not generic
  81  * framebuffer objects ala GL_EXT_framebuffer_object.
  82  *
  83  * \sa _mesa_new_framebuffer
  84  */
  85 struct gl_framebuffer *
  86 _mesa_create_framebuffer(const struct gl_config *visual)
  87 {
  88    struct gl_framebuffer *fb = CALLOC_STRUCT(gl_framebuffer);
  89    assert(visual);
  90    if (fb) {
  91       _mesa_initialize_window_framebuffer(fb, visual);
  92    }
  93    return fb;
  94 }
  95
  96
  97 /**
  98  * Allocate a new gl_framebuffer object.
  99  * This is the default function for ctx->Driver.NewFramebuffer().
 100  * This is for allocating user-created framebuffers, not window-system
 101  * framebuffers!
 102  * \sa _mesa_create_framebuffer
 103  */
 104 struct gl_framebuffer *
 105 _mesa_new_framebuffer(struct gl_context *ctx, GLuint name)
 106 {
 107    struct gl_framebuffer *fb;
 108    (void) ctx;
 109    assert(name != 0);
 110    fb = CALLOC_STRUCT(gl_framebuffer);
 111    if (fb) {
 112       _mesa_initialize_user_framebuffer(fb, name);
 113    }
 114    return fb;
 115 }
 116
 117
 118 /**
 119  * Initialize a gl_framebuffer object.  Typically used to initialize
 120  * window system-created framebuffers, not user-created framebuffers.
 121  * \sa _mesa_initialize_user_framebuffer
 122  */
 123 void
 124 _mesa_initialize_window_framebuffer(struct gl_framebuffer *fb,
 125                                      const struct gl_config *visual)
 126 {
 127    assert(fb);
 128    assert(visual);
 129
 130    memset(fb, 0, sizeof(struct gl_framebuffer));
 131
 132    _glthread_INIT_MUTEX(fb->Mutex);
 133
 134    fb->RefCount = 1;
 135
 136    /* save the visual */
 137    fb->Visual = *visual;
 138
 139    /* Init read/draw renderbuffer state */
 140    if (visual->doubleBufferMode) {
 141       fb->_NumColorDrawBuffers = 1;
 142       fb->ColorDrawBuffer[0] = GL_BACK;
 143       fb->_ColorDrawBufferIndexes[0] = BUFFER_BACK_LEFT;
 144       fb->ColorReadBuffer = GL_BACK;
 145       fb->_ColorReadBufferIndex = BUFFER_BACK_LEFT;
 146    }
 147    else {
 148       fb->_NumColorDrawBuffers = 1;
 149       fb->ColorDrawBuffer[0] = GL_FRONT;
 150       fb->_ColorDrawBufferIndexes[0] = BUFFER_FRONT_LEFT;
 151       fb->ColorReadBuffer = GL_FRONT;
 152       fb->_ColorReadBufferIndex = BUFFER_FRONT_LEFT;
 153    }
 154
 155    fb->Delete = _mesa_destroy_framebuffer;
 156    fb->_Status = GL_FRAMEBUFFER_COMPLETE_EXT;
 157
 158    compute_depth_max(fb);
 159 }
 160
 161
 162 /**
 163  * Initialize a user-created gl_framebuffer object.
 164  * \sa _mesa_initialize_window_framebuffer
 165  */
 166 void
 167 _mesa_initialize_user_framebuffer(struct gl_framebuffer *fb, GLuint name)
 168 {
 169    assert(fb);
 170    assert(name);
 171
 172    memset(fb, 0, sizeof(struct gl_framebuffer));
 173
 174    fb->Name = name;
 175    fb->RefCount = 1;
 176    fb->_NumColorDrawBuffers = 1;
 177    fb->ColorDrawBuffer[0] = GL_COLOR_ATTACHMENT0_EXT;
 178    fb->_ColorDrawBufferIndexes[0] = BUFFER_COLOR0;
 179    fb->ColorReadBuffer = GL_COLOR_ATTACHMENT0_EXT;
 180    fb->_ColorReadBufferIndex = BUFFER_COLOR0;
 181    fb->Delete = _mesa_destroy_framebuffer;
 182    _glthread_INIT_MUTEX(fb->Mutex);
 183 }
 184
 185
 186 /**
 187  * Deallocate buffer and everything attached to it.
 188  * Typically called via the gl_framebuffer->Delete() method.
 189  */
 190 void
 191 _mesa_destroy_framebuffer(struct gl_framebuffer *fb)
 192 {
 193    if (fb) {
 194       _mesa_free_framebuffer_data(fb);
 195       free(fb);
 196    }
 197 }
 198
 199
 200 /**
 201  * Free all the data hanging off the given gl_framebuffer, but don't free
 202  * the gl_framebuffer object itself.
 203  */
 204 void
 205 _mesa_free_framebuffer_data(struct gl_framebuffer *fb)
 206 {
 207    GLuint i;
 208
 209    assert(fb);
 210    assert(fb->RefCount == 0);
 211
 212    _glthread_DESTROY_MUTEX(fb->Mutex);
 213
 214    for (i = 0; i < BUFFER_COUNT; i++) {
 215       struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
 216       if (att->Renderbuffer) {
 217          _mesa_reference_renderbuffer(&att->Renderbuffer, NULL);
 218       }
 219       if (att->Texture) {
 220          _mesa_reference_texobj(&att->Texture, NULL);
 221       }
 222       ASSERT(!att->Renderbuffer);
 223       ASSERT(!att->Texture);
 224       att->Type = GL_NONE;
 225    }
 226 }
 227
 228
 229 /**
 230  * Set *ptr to point to fb, with refcounting and locking.
 231  * This is normally only called from the _mesa_reference_framebuffer() macro
 232  * when there's a real pointer change.
 233  */
 234 void
 235 _mesa_reference_framebuffer_(struct gl_framebuffer **ptr,
 236                              struct gl_framebuffer *fb)
 237 {
 238    if (*ptr) {
 239       /* unreference old renderbuffer */
 240       GLboolean deleteFlag = GL_FALSE;
 241       struct gl_framebuffer *oldFb = *ptr;
 242
 243       _glthread_LOCK_MUTEX(oldFb->Mutex);
 244       ASSERT(oldFb->RefCount > 0);
 245       oldFb->RefCount--;
 246       deleteFlag = (oldFb->RefCount == 0);
 247       _glthread_UNLOCK_MUTEX(oldFb->Mutex);
 248
 249       if (deleteFlag)
 250          oldFb->Delete(oldFb);
 251
 252       *ptr = NULL;
 253    }
 254    assert(!*ptr);
 255
 256    if (fb) {
 257       _glthread_LOCK_MUTEX(fb->Mutex);
 258       fb->RefCount++;
 259       _glthread_UNLOCK_MUTEX(fb->Mutex);
 260       *ptr = fb;
 261    }
 262 }
 263
 264
 265 /**
 266  * Resize the given framebuffer's renderbuffers to the new width and height.
 267  * This should only be used for window-system framebuffers, not
 268  * user-created renderbuffers (i.e. made with GL_EXT_framebuffer_object).
 269  * This will typically be called via ctx->Driver.ResizeBuffers() or directly
 270  * from a device driver.
 271  *
 272  * \note it's possible for ctx to be null since a window can be resized
 273  * without a currently bound rendering context.
 274  */
 275 void
 276 _mesa_resize_framebuffer(struct gl_context *ctx, struct gl_framebuffer *fb,
 277                          GLuint width, GLuint height)
 278 {
 279    GLuint i;
 280
 281    /* XXX I think we could check if the size is not changing
 282     * and return early.
 283     */
 284
 285    /* Can only resize win-sys framebuffer objects */
 286    assert(_mesa_is_winsys_fbo(fb));
 287
 288    for (i = 0; i < BUFFER_COUNT; i++) {
 289       struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
 290       if (att->Type == GL_RENDERBUFFER_EXT && att->Renderbuffer) {
 291          struct gl_renderbuffer *rb = att->Renderbuffer;
 292          /* only resize if size is changing */
 293          if (rb->Width != width || rb->Height != height) {
 294             if (rb->AllocStorage(ctx, rb, rb->InternalFormat, width, height)) {
 295                ASSERT(rb->Width == width);
 296                ASSERT(rb->Height == height);
 297             }
 298             else {
 299                _mesa_error(ctx, GL_OUT_OF_MEMORY, "Resizing framebuffer");
 300                /* no return */
 301             }
 302          }
 303       }
 304    }
 305
 306    fb->Width = width;
 307    fb->Height = height;
 308
 309    if (ctx) {
 310       /* update scissor / window bounds */
 311       _mesa_update_draw_buffer_bounds(ctx);
 312       /* Signal new buffer state so that swrast will update its clipping
 313        * info (the CLIP_BIT flag).
 314        */
 315       ctx->NewState |= _NEW_BUFFERS;
 316    }
 317 }
 318
 319
 320
 321 /**
 322  * XXX THIS IS OBSOLETE - drivers should take care of detecting window
 323  * size changes and act accordingly, likely calling _mesa_resize_framebuffer().
 324  *
 325  * GL_MESA_resize_buffers extension.
 326  *
 327  * When this function is called, we'll ask the window system how large
 328  * the current window is.  If it's a new size, we'll call the driver's
 329  * ResizeBuffers function.  The driver will then resize its color buffers
 330  * as needed, and maybe call the swrast's routine for reallocating
 331  * swrast-managed depth/stencil/accum/etc buffers.
 332  * \note This function should only be called through the GL API, not
 333  * from device drivers (as was done in the past).
 334  */
 335 void
 336 _mesa_resizebuffers( struct gl_context *ctx )
 337 {
 338    FLUSH_VERTICES(ctx, 0);
 339
 340    if (MESA_VERBOSE & VERBOSE_API)
 341       _mesa_debug(ctx, "glResizeBuffersMESA\n");
 342
 343    if (!ctx->Driver.GetBufferSize) {
 344       return;
 345    }
 346
 347    if (ctx->WinSysDrawBuffer) {
 348       GLuint newWidth, newHeight;
 349       struct gl_framebuffer *buffer = ctx->WinSysDrawBuffer;
 350
 351       assert(_mesa_is_winsys_fbo(buffer));
 352
 353       /* ask device driver for size of output buffer */
 354       ctx->Driver.GetBufferSize( buffer, &newWidth, &newHeight );
 355
 356       /* see if size of device driver's color buffer (window) has changed */
 357       if (buffer->Width != newWidth || buffer->Height != newHeight) {
 358          if (ctx->Driver.ResizeBuffers)
 359             ctx->Driver.ResizeBuffers(ctx, buffer, newWidth, newHeight );
 360       }
 361    }
 362
 363    if (ctx->WinSysReadBuffer
 364        && ctx->WinSysReadBuffer != ctx->WinSysDrawBuffer) {
 365       GLuint newWidth, newHeight;
 366       struct gl_framebuffer *buffer = ctx->WinSysReadBuffer;
 367
 368       assert(_mesa_is_winsys_fbo(buffer));
 369
 370       /* ask device driver for size of read buffer */
 371       ctx->Driver.GetBufferSize( buffer, &newWidth, &newHeight );
 372
 373       /* see if size of device driver's color buffer (window) has changed */
 374       if (buffer->Width != newWidth || buffer->Height != newHeight) {
 375          if (ctx->Driver.ResizeBuffers)
 376             ctx->Driver.ResizeBuffers(ctx, buffer, newWidth, newHeight );
 377       }
 378    }
 379
 380    ctx->NewState |= _NEW_BUFFERS;  /* to update scissor / window bounds */
 381 }
 382
 383
 384 /*
 385  * XXX THIS IS OBSOLETE
 386  */
 387 void GLAPIENTRY
 388 _mesa_ResizeBuffersMESA( void )
 389 {
 390    GET_CURRENT_CONTEXT(ctx);
 391
 392    if (ctx->Extensions.MESA_resize_buffers)
 393       _mesa_resizebuffers( ctx );
 394 }
 395
 396
 397
 398 /**
 399  * Examine all the framebuffer's renderbuffers to update the Width/Height
 400  * fields of the framebuffer.  If we have renderbuffers with different
 401  * sizes, set the framebuffer's width and height to the min size.
 402  * Note: this is only intended for user-created framebuffers, not
 403  * window-system framebuffes.
 404  */
 405 static void
 406 update_framebuffer_size(struct gl_context *ctx, struct gl_framebuffer *fb)
 407 {
 408    GLuint minWidth = ~0, minHeight = ~0;
 409    GLuint i;
 410
 411    /* user-created framebuffers only */
 412    assert(_mesa_is_user_fbo(fb));
 413
 414    for (i = 0; i < BUFFER_COUNT; i++) {
 415       struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
 416       const struct gl_renderbuffer *rb = att->Renderbuffer;
 417       if (rb) {
 418          minWidth = MIN2(minWidth, rb->Width);
 419          minHeight = MIN2(minHeight, rb->Height);
 420       }
 421    }
 422
 423    if (minWidth != ~0) {
 424       fb->Width = minWidth;
 425       fb->Height = minHeight;
 426    }
 427    else {
 428       fb->Width = 0;
 429       fb->Height = 0;
 430    }
 431 }
 432
 433
 434 /**
 435  * Update the context's current drawing buffer's Xmin, Xmax, Ymin, Ymax fields.
 436  * These values are computed from the buffer's width and height and
 437  * the scissor box, if it's enabled.
 438  * \param ctx  the GL context.
 439  */
 440 void
 441 _mesa_update_draw_buffer_bounds(struct gl_context *ctx)
 442 {
 443    struct gl_framebuffer *buffer = ctx->DrawBuffer;
 444
 445    if (!buffer)
 446       return;
 447
 448    if (_mesa_is_user_fbo(buffer)) {
 449       /* user-created framebuffer size depends on the renderbuffers */
 450       update_framebuffer_size(ctx, buffer);
 451    }
 452
 453    buffer->_Xmin = 0;
 454    buffer->_Ymin = 0;
 455    buffer->_Xmax = buffer->Width;
 456    buffer->_Ymax = buffer->Height;
 457
 458    if (ctx->Scissor.Enabled) {
 459       if (ctx->Scissor.X > buffer->_Xmin) {
 460          buffer->_Xmin = ctx->Scissor.X;
 461       }
 462       if (ctx->Scissor.Y > buffer->_Ymin) {
 463          buffer->_Ymin = ctx->Scissor.Y;
 464       }
 465       if (ctx->Scissor.X + ctx->Scissor.Width < buffer->_Xmax) {
 466          buffer->_Xmax = ctx->Scissor.X + ctx->Scissor.Width;
 467       }
 468       if (ctx->Scissor.Y + ctx->Scissor.Height < buffer->_Ymax) {
 469          buffer->_Ymax = ctx->Scissor.Y + ctx->Scissor.Height;
 470       }
 471       /* finally, check for empty region */
 472       if (buffer->_Xmin > buffer->_Xmax) {
 473          buffer->_Xmin = buffer->_Xmax;
 474       }
 475       if (buffer->_Ymin > buffer->_Ymax) {
 476          buffer->_Ymin = buffer->_Ymax;
 477       }
 478    }
 479
 480    ASSERT(buffer->_Xmin <= buffer->_Xmax);
 481    ASSERT(buffer->_Ymin <= buffer->_Ymax);
 482 }
 483
 484
 485 /**
 486  * The glGet queries of the framebuffer red/green/blue size, stencil size,
 487  * etc. are satisfied by the fields of ctx->DrawBuffer->Visual.  These can
 488  * change depending on the renderbuffer bindings.  This function updates
 489  * the given framebuffer's Visual from the current renderbuffer bindings.
 490  *
 491  * This may apply to user-created framebuffers or window system framebuffers.
 492  *
 493  * Also note: ctx->DrawBuffer->Visual.depthBits might not equal
 494  * ctx->DrawBuffer->Attachment[BUFFER_DEPTH].Renderbuffer.DepthBits.
 495  * The former one is used to convert floating point depth values into
 496  * integer Z values.
 497  */
 498 void
 499 _mesa_update_framebuffer_visual(struct gl_context *ctx,
 500                                 struct gl_framebuffer *fb)
 501 {
 502    GLuint i;
 503
 504    memset(&fb->Visual, 0, sizeof(fb->Visual));
 505    fb->Visual.rgbMode = GL_TRUE; /* assume this */
 506
 507 #if 0 /* this _might_ be needed */
 508    if (fb->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
 509       /* leave visual fields zero'd */
 510       return;
 511    }
 512 #endif
 513
 514    /* find first RGB renderbuffer */
 515    for (i = 0; i < BUFFER_COUNT; i++) {
 516       if (fb->Attachment[i].Renderbuffer) {
 517          const struct gl_renderbuffer *rb = fb->Attachment[i].Renderbuffer;
 518          const GLenum baseFormat = _mesa_get_format_base_format(rb->Format);
 519          const gl_format fmt = rb->Format;
 520
 521          /* Grab samples and sampleBuffers from any attachment point (assuming
 522           * the framebuffer is complete, we'll get the same answer from all
 523           * attachments).
 524           */
 525          fb->Visual.samples = rb->NumSamples;
 526          fb->Visual.sampleBuffers = rb->NumSamples > 0 ? 1 : 0;
 527
 528          if (_mesa_is_legal_color_format(ctx, baseFormat)) {
 529             fb->Visual.redBits = _mesa_get_format_bits(fmt, GL_RED_BITS);
 530             fb->Visual.greenBits = _mesa_get_format_bits(fmt, GL_GREEN_BITS);
 531             fb->Visual.blueBits = _mesa_get_format_bits(fmt, GL_BLUE_BITS);
 532             fb->Visual.alphaBits = _mesa_get_format_bits(fmt, GL_ALPHA_BITS);
 533             fb->Visual.rgbBits = fb->Visual.redBits
 534                + fb->Visual.greenBits + fb->Visual.blueBits;
 535             if (_mesa_get_format_color_encoding(fmt) == GL_SRGB)
 536                 fb->Visual.sRGBCapable = ctx->Extensions.EXT_framebuffer_sRGB;
 537             break;
 538          }
 539       }
 540    }
 541
 542    fb->Visual.floatMode = GL_FALSE;
 543    for (i = 0; i < BUFFER_COUNT; i++) {
 544       if (fb->Attachment[i].Renderbuffer) {
 545          const struct gl_renderbuffer *rb = fb->Attachment[i].Renderbuffer;
 546          const gl_format fmt = rb->Format;
 547
 548          if (_mesa_get_format_datatype(fmt) == GL_FLOAT) {
 549             fb->Visual.floatMode = GL_TRUE;
 550             break;
 551          }
 552       }
 553    }
 554
 555    if (fb->Attachment[BUFFER_DEPTH].Renderbuffer) {
 556       const struct gl_renderbuffer *rb =
 557          fb->Attachment[BUFFER_DEPTH].Renderbuffer;
 558       const gl_format fmt = rb->Format;
 559       fb->Visual.haveDepthBuffer = GL_TRUE;
 560       fb->Visual.depthBits = _mesa_get_format_bits(fmt, GL_DEPTH_BITS);
 561    }
 562
 563    if (fb->Attachment[BUFFER_STENCIL].Renderbuffer) {
 564       const struct gl_renderbuffer *rb =
 565          fb->Attachment[BUFFER_STENCIL].Renderbuffer;
 566       const gl_format fmt = rb->Format;
 567       fb->Visual.haveStencilBuffer = GL_TRUE;
 568       fb->Visual.stencilBits = _mesa_get_format_bits(fmt, GL_STENCIL_BITS);
 569    }
 570
 571    if (fb->Attachment[BUFFER_ACCUM].Renderbuffer) {
 572       const struct gl_renderbuffer *rb =
 573          fb->Attachment[BUFFER_ACCUM].Renderbuffer;
 574       const gl_format fmt = rb->Format;
 575       fb->Visual.haveAccumBuffer = GL_TRUE;
 576       fb->Visual.accumRedBits = _mesa_get_format_bits(fmt, GL_RED_BITS);
 577       fb->Visual.accumGreenBits = _mesa_get_format_bits(fmt, GL_GREEN_BITS);
 578       fb->Visual.accumBlueBits = _mesa_get_format_bits(fmt, GL_BLUE_BITS);
 579       fb->Visual.accumAlphaBits = _mesa_get_format_bits(fmt, GL_ALPHA_BITS);
 580    }
 581
 582    compute_depth_max(fb);
 583 }
 584
 585
 586 /*
 587  * Example DrawBuffers scenarios:
 588  *
 589  * 1. glDrawBuffer(GL_FRONT_AND_BACK), fixed-func or shader writes to
 590  * "gl_FragColor" or program writes to the "result.color" register:
 591  *
 592  *   fragment color output   renderbuffer
 593  *   ---------------------   ---------------
 594  *   color[0]                Front, Back
 595  *
 596  *
 597  * 2. glDrawBuffers(3, [GL_FRONT, GL_AUX0, GL_AUX1]), shader writes to
 598  * gl_FragData[i] or program writes to result.color[i] registers:
 599  *
 600  *   fragment color output   renderbuffer
 601  *   ---------------------   ---------------
 602  *   color[0]                Front
 603  *   color[1]                Aux0
 604  *   color[3]                Aux1
 605  *
 606  *
 607  * 3. glDrawBuffers(3, [GL_FRONT, GL_AUX0, GL_AUX1]) and shader writes to
 608  * gl_FragColor, or fixed function:
 609  *
 610  *   fragment color output   renderbuffer
 611  *   ---------------------   ---------------
 612  *   color[0]                Front, Aux0, Aux1
 613  *
 614  *
 615  * In either case, the list of renderbuffers is stored in the
 616  * framebuffer->_ColorDrawBuffers[] array and
 617  * framebuffer->_NumColorDrawBuffers indicates the number of buffers.
 618  * The renderer (like swrast) has to look at the current fragment shader
 619  * to see if it writes to gl_FragColor vs. gl_FragData[i] to determine
 620  * how to map color outputs to renderbuffers.
 621  *
 622  * Note that these two calls are equivalent (for fixed function fragment
 623  * shading anyway):
 624  *   a)  glDrawBuffer(GL_FRONT_AND_BACK);  (assuming non-stereo framebuffer)
 625  *   b)  glDrawBuffers(2, [GL_FRONT_LEFT, GL_BACK_LEFT]);
 626  */
 627
 628
 629
 630
 631 /**
 632  * Update the (derived) list of color drawing renderbuffer pointers.
 633  * Later, when we're rendering we'll loop from 0 to _NumColorDrawBuffers
 634  * writing colors.
 635  */
 636 static void
 637 update_color_draw_buffers(struct gl_context *ctx, struct gl_framebuffer *fb)
 638 {
 639    GLuint output;
 640
 641    /* set 0th buffer to NULL now in case _NumColorDrawBuffers is zero */
 642    fb->_ColorDrawBuffers[0] = NULL;
 643
 644    for (output = 0; output < fb->_NumColorDrawBuffers; output++) {
 645       GLint buf = fb->_ColorDrawBufferIndexes[output];
 646       if (buf >= 0) {
 647          fb->_ColorDrawBuffers[output] = fb->Attachment[buf].Renderbuffer;
 648       }
 649       else {
 650          fb->_ColorDrawBuffers[output] = NULL;
 651       }
 652    }
 653 }
 654
 655
 656 /**
 657  * Update the (derived) color read renderbuffer pointer.
 658  * Unlike the DrawBuffer, we can only read from one (or zero) color buffers.
 659  */
 660 static void
 661 update_color_read_buffer(struct gl_context *ctx, struct gl_framebuffer *fb)
 662 {
 663    (void) ctx;
 664    if (fb->_ColorReadBufferIndex == -1 ||
 665        fb->DeletePending ||
 666        fb->Width == 0 ||
 667        fb->Height == 0) {
 668       fb->_ColorReadBuffer = NULL; /* legal! */
 669    }
 670    else {
 671       ASSERT(fb->_ColorReadBufferIndex >= 0);
 672       ASSERT(fb->_ColorReadBufferIndex < BUFFER_COUNT);
 673       fb->_ColorReadBuffer
 674          = fb->Attachment[fb->_ColorReadBufferIndex].Renderbuffer;
 675    }
 676 }
 677
 678
 679 /**
 680  * Update a gl_framebuffer's derived state.
 681  *
 682  * Specifically, update these framebuffer fields:
 683  *    _ColorDrawBuffers
 684  *    _NumColorDrawBuffers
 685  *    _ColorReadBuffer
 686  *
 687  * If the framebuffer is user-created, make sure it's complete.
 688  *
 689  * The following functions (at least) can effect framebuffer state:
 690  * glReadBuffer, glDrawBuffer, glDrawBuffersARB, glFramebufferRenderbufferEXT,
 691  * glRenderbufferStorageEXT.
 692  */
 693 static void
 694 update_framebuffer(struct gl_context *ctx, struct gl_framebuffer *fb)
 695 {
 696    if (_mesa_is_winsys_fbo(fb)) {
 697       /* This is a window-system framebuffer */
 698       /* Need to update the FB's GL_DRAW_BUFFER state to match the
 699        * context state (GL_READ_BUFFER too).
 700        */
 701       if (fb->ColorDrawBuffer[0] != ctx->Color.DrawBuffer[0]) {
 702          _mesa_drawbuffers(ctx, ctx->Const.MaxDrawBuffers,
 703                            ctx->Color.DrawBuffer, NULL);
 704       }
 705    }
 706    else {
 707       /* This is a user-created framebuffer.
 708        * Completeness only matters for user-created framebuffers.
 709        */
 710       if (fb->_Status != GL_FRAMEBUFFER_COMPLETE) {
 711          _mesa_test_framebuffer_completeness(ctx, fb);
 712       }
 713    }
 714
 715    /* Strictly speaking, we don't need to update the draw-state
 716     * if this FB is bound as ctx->ReadBuffer (and conversely, the
 717     * read-state if this FB is bound as ctx->DrawBuffer), but no
 718     * harm.
 719     */
 720    update_color_draw_buffers(ctx, fb);
 721    update_color_read_buffer(ctx, fb);
 722
 723    compute_depth_max(fb);
 724 }
 725
 726
 727 /**
 728  * Update state related to the current draw/read framebuffers.
 729  */
 730 void
 731 _mesa_update_framebuffer(struct gl_context *ctx)
 732 {
 733    struct gl_framebuffer *drawFb;
 734    struct gl_framebuffer *readFb;
 735
 736    assert(ctx);
 737    drawFb = ctx->DrawBuffer;
 738    readFb = ctx->ReadBuffer;
 739
 740    update_framebuffer(ctx, drawFb);
 741    if (readFb != drawFb)
 742       update_framebuffer(ctx, readFb);
 743 }
 744
 745
 746 /**
 747  * Check if the renderbuffer for a read/draw operation exists.
 748  * \param format  a basic image format such as GL_RGB, GL_RGBA, GL_ALPHA,
 749  *                GL_DEPTH_COMPONENT, etc. or GL_COLOR, GL_DEPTH, GL_STENCIL.
 750  * \param reading  if TRUE, we're going to read from the buffer,
 751                    if FALSE, we're going to write to the buffer.
 752  * \return GL_TRUE if buffer exists, GL_FALSE otherwise
 753  */
 754 static GLboolean
 755 renderbuffer_exists(struct gl_context *ctx,
 756                     struct gl_framebuffer *fb,
 757                     GLenum format,
 758                     GLboolean reading)
 759 {
 760    const struct gl_renderbuffer_attachment *att = fb->Attachment;
 761
 762    /* If we don't know the framebuffer status, update it now */
 763    if (fb->_Status == 0) {
 764       _mesa_test_framebuffer_completeness(ctx, fb);
 765    }
 766
 767    if (fb->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
 768       return GL_FALSE;
 769    }
 770
 771    switch (format) {
 772    case GL_COLOR:
 773    case GL_RED:
 774    case GL_GREEN:
 775    case GL_BLUE:
 776    case GL_ALPHA:
 777    case GL_LUMINANCE:
 778    case GL_LUMINANCE_ALPHA:
 779    case GL_INTENSITY:
 780    case GL_RG:
 781    case GL_RGB:
 782    case GL_BGR:
 783    case GL_RGBA:
 784    case GL_BGRA:
 785    case GL_ABGR_EXT:
 786    case GL_RED_INTEGER_EXT:
 787    case GL_RG_INTEGER:
 788    case GL_GREEN_INTEGER_EXT:
 789    case GL_BLUE_INTEGER_EXT:
 790    case GL_ALPHA_INTEGER_EXT:
 791    case GL_RGB_INTEGER_EXT:
 792    case GL_RGBA_INTEGER_EXT:
 793    case GL_BGR_INTEGER_EXT:
 794    case GL_BGRA_INTEGER_EXT:
 795    case GL_LUMINANCE_INTEGER_EXT:
 796    case GL_LUMINANCE_ALPHA_INTEGER_EXT:
 797       if (reading) {
 798          /* about to read from a color buffer */
 799          const struct gl_renderbuffer *readBuf = fb->_ColorReadBuffer;
 800          if (!readBuf) {
 801             return GL_FALSE;
 802          }
 803          ASSERT(_mesa_get_format_bits(readBuf->Format, GL_RED_BITS) > 0 ||
 804                 _mesa_get_format_bits(readBuf->Format, GL_ALPHA_BITS) > 0 ||
 805                 _mesa_get_format_bits(readBuf->Format, GL_TEXTURE_LUMINANCE_SIZE) > 0 ||
 806                 _mesa_get_format_bits(readBuf->Format, GL_TEXTURE_INTENSITY_SIZE) > 0 ||
 807                 _mesa_get_format_bits(readBuf->Format, GL_INDEX_BITS) > 0);
 808       }
 809       else {
 810          /* about to draw to zero or more color buffers (none is OK) */
 811          return GL_TRUE;
 812       }
 813       break;
 814    case GL_DEPTH:
 815    case GL_DEPTH_COMPONENT:
 816       if (att[BUFFER_DEPTH].Type == GL_NONE) {
 817          return GL_FALSE;
 818       }
 819       break;
 820    case GL_STENCIL:
 821    case GL_STENCIL_INDEX:
 822       if (att[BUFFER_STENCIL].Type == GL_NONE) {
 823          return GL_FALSE;
 824       }
 825       break;
 826    case GL_DEPTH_STENCIL_EXT:
 827       if (att[BUFFER_DEPTH].Type == GL_NONE ||
 828           att[BUFFER_STENCIL].Type == GL_NONE) {
 829          return GL_FALSE;
 830       }
 831       break;
 832    default:
 833       _mesa_problem(ctx,
 834                     "Unexpected format 0x%x in renderbuffer_exists",
 835                     format);
 836       return GL_FALSE;
 837    }
 838
 839    /* OK */
 840    return GL_TRUE;
 841 }
 842
 843
 844 /**
 845  * Check if the renderbuffer for a read operation (glReadPixels, glCopyPixels,
 846  * glCopyTex[Sub]Image, etc) exists.
 847  * \param format  a basic image format such as GL_RGB, GL_RGBA, GL_ALPHA,
 848  *                GL_DEPTH_COMPONENT, etc. or GL_COLOR, GL_DEPTH, GL_STENCIL.
 849  * \return GL_TRUE if buffer exists, GL_FALSE otherwise
 850  */
 851 GLboolean
 852 _mesa_source_buffer_exists(struct gl_context *ctx, GLenum format)
 853 {
 854    return renderbuffer_exists(ctx, ctx->ReadBuffer, format, GL_TRUE);
 855 }
 856
 857
 858 /**
 859  * As above, but for drawing operations.
 860  */
 861 GLboolean
 862 _mesa_dest_buffer_exists(struct gl_context *ctx, GLenum format)
 863 {
 864    return renderbuffer_exists(ctx, ctx->DrawBuffer, format, GL_FALSE);
 865 }
 866
 867
 868 /**
 869  * Used to answer the GL_IMPLEMENTATION_COLOR_READ_FORMAT_OES query.
 870  */
 871 GLenum
 872 _mesa_get_color_read_format(struct gl_context *ctx)
 873 {
 874    const GLenum data_type = _mesa_get_format_datatype(
 875                                ctx->ReadBuffer->_ColorReadBuffer->Format);
 876
 877    switch (ctx->ReadBuffer->_ColorReadBuffer->Format) {
 878    case MESA_FORMAT_ARGB8888:
 879       return GL_BGRA;
 880    case MESA_FORMAT_RGB565:
 881       return GL_BGR;
 882    default:
 883       if (data_type == GL_UNSIGNED_INT || data_type == GL_INT) {
 884          return GL_RGBA_INTEGER;
 885       } else {
 886          return GL_RGBA;
 887       }
 888    }
 889 }
 890
 891
 892 /**
 893  * Used to answer the GL_IMPLEMENTATION_COLOR_READ_TYPE_OES query.
 894  */
 895 GLenum
 896 _mesa_get_color_read_type(struct gl_context *ctx)
 897 {
 898    const GLenum data_type = _mesa_get_format_datatype(
 899                                ctx->ReadBuffer->_ColorReadBuffer->Format);
 900
 901    switch (ctx->ReadBuffer->_ColorReadBuffer->Format) {
 902    case MESA_FORMAT_RGB565:
 903       return GL_UNSIGNED_SHORT_5_6_5_REV;
 904    default:
 905       break;
 906    }
 907
 908    switch (data_type) {
 909    case GL_SIGNED_NORMALIZED:
 910       return GL_BYTE;
 911    case GL_UNSIGNED_INT:
 912    case GL_INT:
 913    case GL_FLOAT:
 914       return data_type;
 915    case GL_UNSIGNED_NORMALIZED:
 916    default:
 917       return GL_UNSIGNED_BYTE;
 918    }
 919 }
 920
 921
 922 /**
 923  * Returns the read renderbuffer for the specified format.
 924  */
 925 struct gl_renderbuffer *
 926 _mesa_get_read_renderbuffer_for_format(struct gl_context *ctx,
 927                                        GLenum format)
 928 {
 929    struct gl_framebuffer *rfb = ctx->ReadBuffer;
 930
 931    if (_mesa_is_color_format(format)) {
 932       return rfb->Attachment[rfb->_ColorReadBufferIndex].Renderbuffer;
 933    } else if (_mesa_is_depth_format(format) ||
 934               _mesa_is_depthstencil_format(format)) {
 935       return rfb->Attachment[BUFFER_DEPTH].Renderbuffer;
 936    } else {
 937       return rfb->Attachment[BUFFER_STENCIL].Renderbuffer;
 938    }
 939 }
 940
 941
 942 /**
 943  * Print framebuffer info to stderr, for debugging.
 944  */
 945 void
 946 _mesa_print_framebuffer(const struct gl_framebuffer *fb)
 947 {
 948    GLuint i;
 949
 950    fprintf(stderr, "Mesa Framebuffer %u at %p\n", fb->Name, (void *) fb);
 951    fprintf(stderr, "  Size: %u x %u  Status: %s\n", fb->Width, fb->Height,
 952            _mesa_lookup_enum_by_nr(fb->_Status));
 953    fprintf(stderr, "  Attachments:\n");
 954
 955    for (i = 0; i < BUFFER_COUNT; i++) {
 956       const struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
 957       if (att->Type == GL_TEXTURE) {
 958          const struct gl_texture_image *texImage =
 959             _mesa_get_attachment_teximage_const(att);
 960          fprintf(stderr,
 961                  "  %2d: Texture %u, level %u, face %u, slice %u, complete %d\n",
 962                  i, att->Texture->Name, att->TextureLevel, att->CubeMapFace,
 963                  att->Zoffset, att->Complete);
 964          fprintf(stderr, "       Size: %u x %u x %u  Format %s\n",
 965                  texImage->Width, texImage->Height, texImage->Depth,
 966                  _mesa_get_format_name(texImage->TexFormat));
 967       }
 968       else if (att->Type == GL_RENDERBUFFER) {
 969          fprintf(stderr, "  %2d: Renderbuffer %u, complete %d\n",
 970                  i, att->Renderbuffer->Name, att->Complete);
 971          fprintf(stderr, "       Size: %u x %u  Format %s\n",
 972                  att->Renderbuffer->Width, att->Renderbuffer->Height,
 973                  _mesa_get_format_name(att->Renderbuffer->Format));
 974       }
 975       else {
 976          fprintf(stderr, "  %2d: none\n", i);
 977       }
 978    }
 979 }