src/mesa/main/buffers.c

   1 /*
   2  * Mesa 3-D graphics library
   3  * Version:  7.1
   4  *
   5  * Copyright (C) 1999-2007  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  * \file buffers.c
  28  * glReadBuffer, DrawBuffer functions.
  29  */
  30
  31
  32
  33 #include "glheader.h"
  34 #include "buffers.h"
  35 #include "colormac.h"
  36 #include "context.h"
  37 #include "enums.h"
  38
  39
  40 #define BAD_MASK ~0u
  41
  42
  43 /**
  44  * Return bitmask of BUFFER_BIT_* flags indicating which color buffers are
  45  * available to the rendering context (for drawing or reading).
  46  * This depends on the type of framebuffer.  For window system framebuffers
  47  * we look at the framebuffer's visual.  But for user-create framebuffers we
  48  * look at the number of supported color attachments.
  49  * \param fb  the framebuffer to draw to, or read from
  50  * \return  bitmask of BUFFER_BIT_* flags
  51  */
  52 static GLbitfield
  53 supported_buffer_bitmask(const GLcontext *ctx, const struct gl_framebuffer *fb)
  54 {
  55    GLbitfield mask = 0x0;
  56
  57    if (fb->Name > 0) {
  58       /* A user-created renderbuffer */
  59       GLuint i;
  60       ASSERT(ctx->Extensions.EXT_framebuffer_object);
  61       for (i = 0; i < ctx->Const.MaxColorAttachments; i++) {
  62          mask |= (BUFFER_BIT_COLOR0 << i);
  63       }
  64    }
  65    else {
  66       /* A window system framebuffer */
  67       GLint i;
  68       mask = BUFFER_BIT_FRONT_LEFT; /* always have this */
  69       if (fb->Visual.stereoMode) {
  70          mask |= BUFFER_BIT_FRONT_RIGHT;
  71          if (fb->Visual.doubleBufferMode) {
  72             mask |= BUFFER_BIT_BACK_LEFT | BUFFER_BIT_BACK_RIGHT;
  73          }
  74       }
  75       else if (fb->Visual.doubleBufferMode) {
  76          mask |= BUFFER_BIT_BACK_LEFT;
  77       }
  78
  79       for (i = 0; i < fb->Visual.numAuxBuffers; i++) {
  80          mask |= (BUFFER_BIT_AUX0 << i);
  81       }
  82    }
  83
  84    return mask;
  85 }
  86
  87
  88 /**
  89  * Helper routine used by glDrawBuffer and glDrawBuffersARB.
  90  * Given a GLenum naming one or more color buffers (such as
  91  * GL_FRONT_AND_BACK), return the corresponding bitmask of BUFFER_BIT_* flags.
  92  */
  93 static GLbitfield
  94 draw_buffer_enum_to_bitmask(GLenum buffer)
  95 {
  96    switch (buffer) {
  97       case GL_NONE:
  98          return 0;
  99       case GL_FRONT:
 100          return BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_FRONT_RIGHT;
 101       case GL_BACK:
 102          return BUFFER_BIT_BACK_LEFT | BUFFER_BIT_BACK_RIGHT;
 103       case GL_RIGHT:
 104          return BUFFER_BIT_FRONT_RIGHT | BUFFER_BIT_BACK_RIGHT;
 105       case GL_FRONT_RIGHT:
 106          return BUFFER_BIT_FRONT_RIGHT;
 107       case GL_BACK_RIGHT:
 108          return BUFFER_BIT_BACK_RIGHT;
 109       case GL_BACK_LEFT:
 110          return BUFFER_BIT_BACK_LEFT;
 111       case GL_FRONT_AND_BACK:
 112          return BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_BACK_LEFT
 113               | BUFFER_BIT_FRONT_RIGHT | BUFFER_BIT_BACK_RIGHT;
 114       case GL_LEFT:
 115          return BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_BACK_LEFT;
 116       case GL_FRONT_LEFT:
 117          return BUFFER_BIT_FRONT_LEFT;
 118       case GL_AUX0:
 119          return BUFFER_BIT_AUX0;
 120       case GL_AUX1:
 121       case GL_AUX2:
 122       case GL_AUX3:
 123          return 1 << BUFFER_COUNT; /* invalid, but not BAD_MASK */
 124       case GL_COLOR_ATTACHMENT0_EXT:
 125          return BUFFER_BIT_COLOR0;
 126       case GL_COLOR_ATTACHMENT1_EXT:
 127          return BUFFER_BIT_COLOR1;
 128       case GL_COLOR_ATTACHMENT2_EXT:
 129          return BUFFER_BIT_COLOR2;
 130       case GL_COLOR_ATTACHMENT3_EXT:
 131          return BUFFER_BIT_COLOR3;
 132       case GL_COLOR_ATTACHMENT4_EXT:
 133          return BUFFER_BIT_COLOR4;
 134       case GL_COLOR_ATTACHMENT5_EXT:
 135          return BUFFER_BIT_COLOR5;
 136       case GL_COLOR_ATTACHMENT6_EXT:
 137          return BUFFER_BIT_COLOR6;
 138       case GL_COLOR_ATTACHMENT7_EXT:
 139          return BUFFER_BIT_COLOR7;
 140       default:
 141          /* error */
 142          return BAD_MASK;
 143    }
 144 }
 145
 146
 147 /**
 148  * Helper routine used by glReadBuffer.
 149  * Given a GLenum naming a color buffer, return the index of the corresponding
 150  * renderbuffer (a BUFFER_* value).
 151  * return -1 for an invalid buffer.
 152  */
 153 static GLint
 154 read_buffer_enum_to_index(GLenum buffer)
 155 {
 156    switch (buffer) {
 157       case GL_FRONT:
 158          return BUFFER_FRONT_LEFT;
 159       case GL_BACK:
 160          return BUFFER_BACK_LEFT;
 161       case GL_RIGHT:
 162          return BUFFER_FRONT_RIGHT;
 163       case GL_FRONT_RIGHT:
 164          return BUFFER_FRONT_RIGHT;
 165       case GL_BACK_RIGHT:
 166          return BUFFER_BACK_RIGHT;
 167       case GL_BACK_LEFT:
 168          return BUFFER_BACK_LEFT;
 169       case GL_LEFT:
 170          return BUFFER_FRONT_LEFT;
 171       case GL_FRONT_LEFT:
 172          return BUFFER_FRONT_LEFT;
 173       case GL_AUX0:
 174          return BUFFER_AUX0;
 175       case GL_AUX1:
 176       case GL_AUX2:
 177       case GL_AUX3:
 178          return BUFFER_COUNT; /* invalid, but not -1 */
 179       case GL_COLOR_ATTACHMENT0_EXT:
 180          return BUFFER_COLOR0;
 181       case GL_COLOR_ATTACHMENT1_EXT:
 182          return BUFFER_COLOR1;
 183       case GL_COLOR_ATTACHMENT2_EXT:
 184          return BUFFER_COLOR2;
 185       case GL_COLOR_ATTACHMENT3_EXT:
 186          return BUFFER_COLOR3;
 187       case GL_COLOR_ATTACHMENT4_EXT:
 188          return BUFFER_COLOR4;
 189       case GL_COLOR_ATTACHMENT5_EXT:
 190          return BUFFER_COLOR5;
 191       case GL_COLOR_ATTACHMENT6_EXT:
 192          return BUFFER_COLOR6;
 193       case GL_COLOR_ATTACHMENT7_EXT:
 194          return BUFFER_COLOR7;
 195       default:
 196          /* error */
 197          return -1;
 198    }
 199 }
 200
 201
 202 /**
 203  * Called by glDrawBuffer().
 204  * Specify which renderbuffer(s) to draw into for the first color output.
 205  * <buffer> can name zero, one, two or four renderbuffers!
 206  * \sa _mesa_DrawBuffersARB
 207  *
 208  * \param buffer  buffer token such as GL_LEFT or GL_FRONT_AND_BACK, etc.
 209  *
 210  * Note that the behaviour of this function depends on whether the
 211  * current ctx->DrawBuffer is a window-system framebuffer (Name=0) or
 212  * a user-created framebuffer object (Name!=0).
 213  *   In the former case, we update the per-context ctx->Color.DrawBuffer
 214  *   state var _and_ the FB's ColorDrawBuffer state.
 215  *   In the later case, we update the FB's ColorDrawBuffer state only.
 216  *
 217  * Furthermore, upon a MakeCurrent() or BindFramebuffer() call, if the
 218  * new FB is a window system FB, we need to re-update the FB's
 219  * ColorDrawBuffer state to match the context.  This is handled in
 220  * _mesa_update_framebuffer().
 221  *
 222  * See the GL_EXT_framebuffer_object spec for more info.
 223  */
 224 void GLAPIENTRY
 225 _mesa_DrawBuffer(GLenum buffer)
 226 {
 227    GLbitfield destMask;
 228    GET_CURRENT_CONTEXT(ctx);
 229    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx); /* too complex... */
 230
 231    if (MESA_VERBOSE & VERBOSE_API) {
 232       _mesa_debug(ctx, "glDrawBuffer %s\n", _mesa_lookup_enum_by_nr(buffer));
 233    }
 234
 235    if (buffer == GL_NONE) {
 236       destMask = 0x0;
 237    }
 238    else {
 239       const GLbitfield supportedMask
 240          = supported_buffer_bitmask(ctx, ctx->DrawBuffer);
 241       destMask = draw_buffer_enum_to_bitmask(buffer);
 242       if (destMask == BAD_MASK) {
 243          /* totally bogus buffer */
 244          _mesa_error(ctx, GL_INVALID_ENUM, "glDrawBuffer(buffer=0x%x)", buffer);
 245          return;
 246       }
 247       destMask &= supportedMask;
 248       if (destMask == 0x0) {
 249          /* none of the named color buffers exist! */
 250          _mesa_error(ctx, GL_INVALID_OPERATION,
 251                      "glDrawBuffer(buffer=0x%x)", buffer);
 252          return;
 253       }
 254    }
 255
 256    /* if we get here, there's no error so set new state */
 257    _mesa_drawbuffers(ctx, 1, &buffer, &destMask);
 258
 259    /*
 260     * Call device driver function.
 261     */
 262    if (ctx->Driver.DrawBuffers)
 263       ctx->Driver.DrawBuffers(ctx, 1, &buffer);
 264    else if (ctx->Driver.DrawBuffer)
 265       ctx->Driver.DrawBuffer(ctx, buffer);
 266 }
 267
 268
 269 /**
 270  * Called by glDrawBuffersARB; specifies the destination color renderbuffers
 271  * for N fragment program color outputs.
 272  * \sa _mesa_DrawBuffer
 273  * \param n  number of outputs
 274  * \param buffers  array [n] of renderbuffer names.  Unlike glDrawBuffer, the
 275  *                 names cannot specify more than one buffer.  For example,
 276  *                 GL_FRONT_AND_BACK is illegal.
 277  */
 278 void GLAPIENTRY
 279 _mesa_DrawBuffersARB(GLsizei n, const GLenum *buffers)
 280 {
 281    GLint output;
 282    GLbitfield usedBufferMask, supportedMask;
 283    GLbitfield destMask[MAX_DRAW_BUFFERS];
 284    GET_CURRENT_CONTEXT(ctx);
 285    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
 286
 287    /* Turns out n==0 is a valid input that should not produce an error.
 288     * The remaining code below correctly handles the n==0 case.
 289     */
 290    if (n < 0 || n > (GLsizei) ctx->Const.MaxDrawBuffers) {
 291       _mesa_error(ctx, GL_INVALID_VALUE, "glDrawBuffersARB(n)");
 292       return;
 293    }
 294
 295    supportedMask = supported_buffer_bitmask(ctx, ctx->DrawBuffer);
 296    usedBufferMask = 0x0;
 297
 298    /* complicated error checking... */
 299    for (output = 0; output < n; output++) {
 300       if (buffers[output] == GL_NONE) {
 301          destMask[output] = 0x0;
 302       }
 303       else {
 304          destMask[output] = draw_buffer_enum_to_bitmask(buffers[output]);
 305          if (destMask[output] == BAD_MASK
 306              || _mesa_bitcount(destMask[output]) > 1) {
 307             _mesa_error(ctx, GL_INVALID_ENUM, "glDrawBuffersARB(buffer)");
 308             return;
 309          }
 310          destMask[output] &= supportedMask;
 311          if (destMask[output] == 0) {
 312             _mesa_error(ctx, GL_INVALID_OPERATION,
 313                         "glDrawBuffersARB(unsupported buffer)");
 314             return;
 315          }
 316          if (destMask[output] & usedBufferMask) {
 317             /* can't specify a dest buffer more than once! */
 318             _mesa_error(ctx, GL_INVALID_OPERATION,
 319                         "glDrawBuffersARB(duplicated buffer)");
 320             return;
 321          }
 322
 323          /* update bitmask */
 324          usedBufferMask |= destMask[output];
 325       }
 326    }
 327
 328    /* OK, if we get here, there were no errors so set the new state */
 329    _mesa_drawbuffers(ctx, n, buffers, destMask);
 330
 331    /*
 332     * Call device driver function.  Note that n can be equal to 0,
 333     * in which case we don't want to reference buffers[0], which
 334     * may not be valid.
 335     */
 336    if (ctx->Driver.DrawBuffers)
 337       ctx->Driver.DrawBuffers(ctx, n, buffers);
 338    else if (ctx->Driver.DrawBuffer)
 339       ctx->Driver.DrawBuffer(ctx, n > 0 ? buffers[0] : GL_NONE);
 340 }
 341
 342
 343 /**
 344  * Helper function to set the GL_DRAW_BUFFER state in the context and
 345  * current FBO.  Called via glDrawBuffer(), glDrawBuffersARB()
 346  *
 347  * All error checking will have been done prior to calling this function
 348  * so nothing should go wrong at this point.
 349  *
 350  * \param ctx  current context
 351  * \param n    number of color outputs to set
 352  * \param buffers  array[n] of colorbuffer names, like GL_LEFT.
 353  * \param destMask  array[n] of BUFFER_BIT_* bitmasks which correspond to the
 354  *                  colorbuffer names.  (i.e. GL_FRONT_AND_BACK =>
 355  *                  BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_BACK_LEFT).
 356  */
 357 void
 358 _mesa_drawbuffers(GLcontext *ctx, GLuint n, const GLenum *buffers,
 359                   const GLbitfield *destMask)
 360 {
 361    struct gl_framebuffer *fb = ctx->DrawBuffer;
 362    GLbitfield mask[MAX_DRAW_BUFFERS];
 363    GLboolean newState = GL_FALSE;
 364
 365    if (!destMask) {
 366       /* compute destMask values now */
 367       const GLbitfield supportedMask = supported_buffer_bitmask(ctx, fb);
 368       GLuint output;
 369       for (output = 0; output < n; output++) {
 370          mask[output] = draw_buffer_enum_to_bitmask(buffers[output]);
 371          ASSERT(mask[output] != BAD_MASK);
 372          mask[output] &= supportedMask;
 373       }
 374       destMask = mask;
 375    }
 376
 377    /*
 378     * If n==1, destMask[0] may have up to four bits set.
 379     * Otherwise, destMask[x] can only have one bit set.
 380     */
 381    if (n == 1) {
 382       GLuint count = 0, destMask0 = destMask[0];
 383       while (destMask0) {
 384          GLint bufIndex = _mesa_ffs(destMask0) - 1;
 385          if (fb->_ColorDrawBufferIndexes[count] != bufIndex) {
 386             fb->_ColorDrawBufferIndexes[count] = bufIndex;
 387             newState = GL_TRUE;
 388          }
 389          count++;
 390          destMask0 &= ~(1 << bufIndex);
 391       }
 392       fb->ColorDrawBuffer[0] = buffers[0];
 393       if (fb->_NumColorDrawBuffers != count) {
 394          fb->_NumColorDrawBuffers = count;
 395          newState = GL_TRUE;
 396       }
 397    }
 398    else {
 399       GLuint buf, count = 0;
 400       for (buf = 0; buf < n; buf++ ) {
 401          if (destMask[buf]) {
 402             GLint bufIndex = _mesa_ffs(destMask[buf]) - 1;
 403             /* only one bit should be set in the destMask[buf] field */
 404             ASSERT(_mesa_bitcount(destMask[buf]) == 1);
 405             if (fb->_ColorDrawBufferIndexes[buf] != bufIndex) {
 406                fb->_ColorDrawBufferIndexes[buf] = bufIndex;
 407                newState = GL_TRUE;
 408             }
 409             fb->ColorDrawBuffer[buf] = buffers[buf];
 410             count = buf + 1;
 411          }
 412          else {
 413             if (fb->_ColorDrawBufferIndexes[buf] != -1) {
 414                fb->_ColorDrawBufferIndexes[buf] = -1;
 415                newState = GL_TRUE;
 416             }
 417          }
 418       }
 419       /* set remaining outputs to -1 (GL_NONE) */
 420       while (buf < ctx->Const.MaxDrawBuffers) {
 421          if (fb->_ColorDrawBufferIndexes[buf] != -1) {
 422             fb->_ColorDrawBufferIndexes[buf] = -1;
 423             newState = GL_TRUE;
 424          }
 425          fb->ColorDrawBuffer[buf] = GL_NONE;
 426          buf++;
 427       }
 428       fb->_NumColorDrawBuffers = count;
 429    }
 430
 431    if (fb->Name == 0) {
 432       /* also set context drawbuffer state */
 433       GLuint buf;
 434       for (buf = 0; buf < ctx->Const.MaxDrawBuffers; buf++) {
 435          if (ctx->Color.DrawBuffer[buf] != fb->ColorDrawBuffer[buf]) {
 436             ctx->Color.DrawBuffer[buf] = fb->ColorDrawBuffer[buf];
 437             newState = GL_TRUE;
 438          }
 439       }
 440    }
 441
 442    if (newState)
 443       FLUSH_VERTICES(ctx, _NEW_BUFFERS);
 444 }
 445
 446
 447 /**
 448  * Like \sa _mesa_drawbuffers(), this is a helper function for setting
 449  * GL_READ_BUFFER state in the context and current FBO.
 450  * \param ctx  the rendering context
 451  * \param buffer  GL_FRONT, GL_BACK, GL_COLOR_ATTACHMENT0, etc.
 452  * \param bufferIndex  the numerical index corresponding to 'buffer'
 453  */
 454 void
 455 _mesa_readbuffer(GLcontext *ctx, GLenum buffer, GLint bufferIndex)
 456 {
 457    struct gl_framebuffer *fb = ctx->ReadBuffer;
 458
 459    if (fb->Name == 0) {
 460       /* Only update the per-context READ_BUFFER state if we're bound to
 461        * a window-system framebuffer.
 462        */
 463       ctx->Pixel.ReadBuffer = buffer;
 464    }
 465
 466    fb->ColorReadBuffer = buffer;
 467    fb->_ColorReadBufferIndex = bufferIndex;
 468
 469    ctx->NewState |= _NEW_BUFFERS;
 470 }
 471
 472
 473
 474 /**
 475  * Called by glReadBuffer to set the source renderbuffer for reading pixels.
 476  * \param mode color buffer such as GL_FRONT, GL_BACK, etc.
 477  */
 478 void GLAPIENTRY
 479 _mesa_ReadBuffer(GLenum buffer)
 480 {
 481    struct gl_framebuffer *fb;
 482    GLbitfield supportedMask;
 483    GLint srcBuffer;
 484    GET_CURRENT_CONTEXT(ctx);
 485    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
 486
 487    if (MESA_VERBOSE & VERBOSE_API)
 488       _mesa_debug(ctx, "glReadBuffer %s\n", _mesa_lookup_enum_by_nr(buffer));
 489
 490    fb = ctx->ReadBuffer;
 491
 492    if (MESA_VERBOSE & VERBOSE_API)
 493       _mesa_debug(ctx, "glReadBuffer %s\n", _mesa_lookup_enum_by_nr(buffer));
 494
 495    if (fb->Name > 0 && buffer == GL_NONE) {
 496       /* This is legal for user-created framebuffer objects */
 497       srcBuffer = -1;
 498    }
 499    else {
 500       /* general case / window-system framebuffer */
 501       srcBuffer = read_buffer_enum_to_index(buffer);
 502       if (srcBuffer == -1) {
 503          _mesa_error(ctx, GL_INVALID_ENUM,
 504                      "glReadBuffer(buffer=0x%x)", buffer);
 505          return;
 506       }
 507       supportedMask = supported_buffer_bitmask(ctx, fb);
 508       if (((1 << srcBuffer) & supportedMask) == 0) {
 509          _mesa_error(ctx, GL_INVALID_OPERATION,
 510                      "glReadBuffer(buffer=0x%x)", buffer);
 511          return;
 512       }
 513    }
 514
 515    /* OK, all error checking has been completed now */
 516
 517    _mesa_readbuffer(ctx, buffer, srcBuffer);
 518    ctx->NewState |= _NEW_BUFFERS;
 519
 520    /*
 521     * Call device driver function.
 522     */
 523    if (ctx->Driver.ReadBuffer)
 524       (*ctx->Driver.ReadBuffer)(ctx, buffer);
 525 }