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 #include "fbobject.h"
  39 #include "state.h"
  40
  41
  42 #define BAD_MASK ~0u
  43
  44
  45 /**
  46  * Return bitmask of BUFFER_BIT_* flags indicating which color buffers are
  47  * available to the rendering context (for drawing or reading).
  48  * This depends on the type of framebuffer.  For window system framebuffers
  49  * we look at the framebuffer's visual.  But for user-create framebuffers we
  50  * look at the number of supported color attachments.
  51  * \param fb  the framebuffer to draw to, or read from
  52  * \return  bitmask of BUFFER_BIT_* flags
  53  */
  54 static GLbitfield
  55 supported_buffer_bitmask(const GLcontext *ctx, const struct gl_framebuffer *fb)
  56 {
  57    GLbitfield mask = 0x0;
  58
  59    if (fb->Name > 0) {
  60       /* A user-created renderbuffer */
  61       GLuint i;
  62       ASSERT(ctx->Extensions.EXT_framebuffer_object);
  63       for (i = 0; i < ctx->Const.MaxColorAttachments; i++) {
  64          mask |= (BUFFER_BIT_COLOR0 << i);
  65       }
  66    }
  67    else {
  68       /* A window system framebuffer */
  69       GLint i;
  70       mask = BUFFER_BIT_FRONT_LEFT; /* always have this */
  71       if (fb->Visual.stereoMode) {
  72          mask |= BUFFER_BIT_FRONT_RIGHT;
  73          if (fb->Visual.doubleBufferMode) {
  74             mask |= BUFFER_BIT_BACK_LEFT | BUFFER_BIT_BACK_RIGHT;
  75          }
  76       }
  77       else if (fb->Visual.doubleBufferMode) {
  78          mask |= BUFFER_BIT_BACK_LEFT;
  79       }
  80
  81       for (i = 0; i < fb->Visual.numAuxBuffers; i++) {
  82          mask |= (BUFFER_BIT_AUX0 << i);
  83       }
  84    }
  85
  86    return mask;
  87 }
  88
  89
  90 /**
  91  * Helper routine used by glDrawBuffer and glDrawBuffersARB.
  92  * Given a GLenum naming one or more color buffers (such as
  93  * GL_FRONT_AND_BACK), return the corresponding bitmask of BUFFER_BIT_* flags.
  94  */
  95 static GLbitfield
  96 draw_buffer_enum_to_bitmask(GLenum buffer)
  97 {
  98    switch (buffer) {
  99       case GL_NONE:
 100          return 0;
 101       case GL_FRONT:
 102          return BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_FRONT_RIGHT;
 103       case GL_BACK:
 104          return BUFFER_BIT_BACK_LEFT | BUFFER_BIT_BACK_RIGHT;
 105       case GL_RIGHT:
 106          return BUFFER_BIT_FRONT_RIGHT | BUFFER_BIT_BACK_RIGHT;
 107       case GL_FRONT_RIGHT:
 108          return BUFFER_BIT_FRONT_RIGHT;
 109       case GL_BACK_RIGHT:
 110          return BUFFER_BIT_BACK_RIGHT;
 111       case GL_BACK_LEFT:
 112          return BUFFER_BIT_BACK_LEFT;
 113       case GL_FRONT_AND_BACK:
 114          return BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_BACK_LEFT
 115               | BUFFER_BIT_FRONT_RIGHT | BUFFER_BIT_BACK_RIGHT;
 116       case GL_LEFT:
 117          return BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_BACK_LEFT;
 118       case GL_FRONT_LEFT:
 119          return BUFFER_BIT_FRONT_LEFT;
 120       case GL_AUX0:
 121          return BUFFER_BIT_AUX0;
 122       case GL_AUX1:
 123       case GL_AUX2:
 124       case GL_AUX3:
 125          return 1 << BUFFER_COUNT; /* invalid, but not BAD_MASK */
 126       case GL_COLOR_ATTACHMENT0_EXT:
 127          return BUFFER_BIT_COLOR0;
 128       case GL_COLOR_ATTACHMENT1_EXT:
 129          return BUFFER_BIT_COLOR1;
 130       case GL_COLOR_ATTACHMENT2_EXT:
 131          return BUFFER_BIT_COLOR2;
 132       case GL_COLOR_ATTACHMENT3_EXT:
 133          return BUFFER_BIT_COLOR3;
 134       case GL_COLOR_ATTACHMENT4_EXT:
 135          return BUFFER_BIT_COLOR4;
 136       case GL_COLOR_ATTACHMENT5_EXT:
 137          return BUFFER_BIT_COLOR5;
 138       case GL_COLOR_ATTACHMENT6_EXT:
 139          return BUFFER_BIT_COLOR6;
 140       case GL_COLOR_ATTACHMENT7_EXT:
 141          return BUFFER_BIT_COLOR7;
 142       default:
 143          /* error */
 144          return BAD_MASK;
 145    }
 146 }
 147
 148
 149 /**
 150  * Helper routine used by glReadBuffer.
 151  * Given a GLenum naming a color buffer, return the index of the corresponding
 152  * renderbuffer (a BUFFER_* value).
 153  * return -1 for an invalid buffer.
 154  */
 155 static GLint
 156 read_buffer_enum_to_index(GLenum buffer)
 157 {
 158    switch (buffer) {
 159       case GL_FRONT:
 160          return BUFFER_FRONT_LEFT;
 161       case GL_BACK:
 162          return BUFFER_BACK_LEFT;
 163       case GL_RIGHT:
 164          return BUFFER_FRONT_RIGHT;
 165       case GL_FRONT_RIGHT:
 166          return BUFFER_FRONT_RIGHT;
 167       case GL_BACK_RIGHT:
 168          return BUFFER_BACK_RIGHT;
 169       case GL_BACK_LEFT:
 170          return BUFFER_BACK_LEFT;
 171       case GL_LEFT:
 172          return BUFFER_FRONT_LEFT;
 173       case GL_FRONT_LEFT:
 174          return BUFFER_FRONT_LEFT;
 175       case GL_AUX0:
 176          return BUFFER_AUX0;
 177       case GL_AUX1:
 178       case GL_AUX2:
 179       case GL_AUX3:
 180          return BUFFER_COUNT; /* invalid, but not -1 */
 181       case GL_COLOR_ATTACHMENT0_EXT:
 182          return BUFFER_COLOR0;
 183       case GL_COLOR_ATTACHMENT1_EXT:
 184          return BUFFER_COLOR1;
 185       case GL_COLOR_ATTACHMENT2_EXT:
 186          return BUFFER_COLOR2;
 187       case GL_COLOR_ATTACHMENT3_EXT:
 188          return BUFFER_COLOR3;
 189       case GL_COLOR_ATTACHMENT4_EXT:
 190          return BUFFER_COLOR4;
 191       case GL_COLOR_ATTACHMENT5_EXT:
 192          return BUFFER_COLOR5;
 193       case GL_COLOR_ATTACHMENT6_EXT:
 194          return BUFFER_COLOR6;
 195       case GL_COLOR_ATTACHMENT7_EXT:
 196          return BUFFER_COLOR7;
 197       default:
 198          /* error */
 199          return -1;
 200    }
 201 }
 202
 203
 204 /**
 205  * Called by glDrawBuffer().
 206  * Specify which renderbuffer(s) to draw into for the first color output.
 207  * <buffer> can name zero, one, two or four renderbuffers!
 208  * \sa _mesa_DrawBuffersARB
 209  *
 210  * \param buffer  buffer token such as GL_LEFT or GL_FRONT_AND_BACK, etc.
 211  *
 212  * Note that the behaviour of this function depends on whether the
 213  * current ctx->DrawBuffer is a window-system framebuffer (Name=0) or
 214  * a user-created framebuffer object (Name!=0).
 215  *   In the former case, we update the per-context ctx->Color.DrawBuffer
 216  *   state var _and_ the FB's ColorDrawBuffer state.
 217  *   In the later case, we update the FB's ColorDrawBuffer state only.
 218  *
 219  * Furthermore, upon a MakeCurrent() or BindFramebuffer() call, if the
 220  * new FB is a window system FB, we need to re-update the FB's
 221  * ColorDrawBuffer state to match the context.  This is handled in
 222  * _mesa_update_framebuffer().
 223  *
 224  * See the GL_EXT_framebuffer_object spec for more info.
 225  */
 226 void GLAPIENTRY
 227 _mesa_DrawBuffer(GLenum buffer)
 228 {
 229    GLbitfield destMask;
 230    GET_CURRENT_CONTEXT(ctx);
 231    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx); /* too complex... */
 232
 233    if (MESA_VERBOSE & VERBOSE_API) {
 234       _mesa_debug(ctx, "glDrawBuffer %s\n", _mesa_lookup_enum_by_nr(buffer));
 235    }
 236
 237    if (buffer == GL_NONE) {
 238       destMask = 0x0;
 239    }
 240    else {
 241       const GLbitfield supportedMask
 242          = supported_buffer_bitmask(ctx, ctx->DrawBuffer);
 243       destMask = draw_buffer_enum_to_bitmask(buffer);
 244       if (destMask == BAD_MASK) {
 245          /* totally bogus buffer */
 246          _mesa_error(ctx, GL_INVALID_ENUM, "glDrawBuffer(buffer=0x%x)", buffer);
 247          return;
 248       }
 249       destMask &= supportedMask;
 250       if (destMask == 0x0) {
 251          /* none of the named color buffers exist! */
 252          _mesa_error(ctx, GL_INVALID_OPERATION,
 253                      "glDrawBuffer(buffer=0x%x)", buffer);
 254          return;
 255       }
 256    }
 257
 258    /* if we get here, there's no error so set new state */
 259    _mesa_drawbuffers(ctx, 1, &buffer, &destMask);
 260
 261    /*
 262     * Call device driver function.
 263     */
 264    if (ctx->Driver.DrawBuffers)
 265       ctx->Driver.DrawBuffers(ctx, 1, &buffer);
 266    else if (ctx->Driver.DrawBuffer)
 267       ctx->Driver.DrawBuffer(ctx, buffer);
 268 }
 269
 270
 271 /**
 272  * Called by glDrawBuffersARB; specifies the destination color renderbuffers
 273  * for N fragment program color outputs.
 274  * \sa _mesa_DrawBuffer
 275  * \param n  number of outputs
 276  * \param buffers  array [n] of renderbuffer names.  Unlike glDrawBuffer, the
 277  *                 names cannot specify more than one buffer.  For example,
 278  *                 GL_FRONT_AND_BACK is illegal.
 279  */
 280 void GLAPIENTRY
 281 _mesa_DrawBuffersARB(GLsizei n, const GLenum *buffers)
 282 {
 283    GLint output;
 284    GLbitfield usedBufferMask, supportedMask;
 285    GLbitfield destMask[MAX_DRAW_BUFFERS];
 286    GET_CURRENT_CONTEXT(ctx);
 287    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
 288
 289    /* Turns out n==0 is a valid input that should not produce an error.
 290     * The remaining code below correctly handles the n==0 case.
 291     */
 292    if (n < 0 || n > (GLsizei) ctx->Const.MaxDrawBuffers) {
 293       _mesa_error(ctx, GL_INVALID_VALUE, "glDrawBuffersARB(n)");
 294       return;
 295    }
 296
 297    supportedMask = supported_buffer_bitmask(ctx, ctx->DrawBuffer);
 298    usedBufferMask = 0x0;
 299
 300    /* complicated error checking... */
 301    for (output = 0; output < n; output++) {
 302       if (buffers[output] == GL_NONE) {
 303          destMask[output] = 0x0;
 304       }
 305       else {
 306          destMask[output] = draw_buffer_enum_to_bitmask(buffers[output]);
 307          if (destMask[output] == BAD_MASK
 308              || _mesa_bitcount(destMask[output]) > 1) {
 309             _mesa_error(ctx, GL_INVALID_ENUM, "glDrawBuffersARB(buffer)");
 310             return;
 311          }
 312          destMask[output] &= supportedMask;
 313          if (destMask[output] == 0) {
 314             _mesa_error(ctx, GL_INVALID_OPERATION,
 315                         "glDrawBuffersARB(unsupported buffer)");
 316             return;
 317          }
 318          if (destMask[output] & usedBufferMask) {
 319             /* can't specify a dest buffer more than once! */
 320             _mesa_error(ctx, GL_INVALID_OPERATION,
 321                         "glDrawBuffersARB(duplicated buffer)");
 322             return;
 323          }
 324
 325          /* update bitmask */
 326          usedBufferMask |= destMask[output];
 327       }
 328    }
 329
 330    /* OK, if we get here, there were no errors so set the new state */
 331    _mesa_drawbuffers(ctx, n, buffers, destMask);
 332
 333    /*
 334     * Call device driver function.  Note that n can be equal to 0,
 335     * in which case we don't want to reference buffers[0], which
 336     * may not be valid.
 337     */
 338    if (ctx->Driver.DrawBuffers)
 339       ctx->Driver.DrawBuffers(ctx, n, buffers);
 340    else if (ctx->Driver.DrawBuffer)
 341       ctx->Driver.DrawBuffer(ctx, n > 0 ? buffers[0] : GL_NONE);
 342 }
 343
 344
 345 /**
 346  * Helper function to set the GL_DRAW_BUFFER state in the context and
 347  * current FBO.  Called via glDrawBuffer(), glDrawBuffersARB()
 348  *
 349  * All error checking will have been done prior to calling this function
 350  * so nothing should go wrong at this point.
 351  *
 352  * \param ctx  current context
 353  * \param n    number of color outputs to set
 354  * \param buffers  array[n] of colorbuffer names, like GL_LEFT.
 355  * \param destMask  array[n] of BUFFER_BIT_* bitmasks which correspond to the
 356  *                  colorbuffer names.  (i.e. GL_FRONT_AND_BACK =>
 357  *                  BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_BACK_LEFT).
 358  */
 359 void
 360 _mesa_drawbuffers(GLcontext *ctx, GLuint n, const GLenum *buffers,
 361                   const GLbitfield *destMask)
 362 {
 363    struct gl_framebuffer *fb = ctx->DrawBuffer;
 364    GLbitfield mask[MAX_DRAW_BUFFERS];
 365    GLboolean newState = GL_FALSE;
 366
 367    if (!destMask) {
 368       /* compute destMask values now */
 369       const GLbitfield supportedMask = supported_buffer_bitmask(ctx, fb);
 370       GLuint output;
 371       for (output = 0; output < n; output++) {
 372          mask[output] = draw_buffer_enum_to_bitmask(buffers[output]);
 373          ASSERT(mask[output] != BAD_MASK);
 374          mask[output] &= supportedMask;
 375       }
 376       destMask = mask;
 377    }
 378
 379    /*
 380     * If n==1, destMask[0] may have up to four bits set.
 381     * Otherwise, destMask[x] can only have one bit set.
 382     */
 383    if (n == 1) {
 384       GLuint count = 0, destMask0 = destMask[0];
 385       while (destMask0) {
 386          GLint bufIndex = _mesa_ffs(destMask0) - 1;
 387          if (fb->_ColorDrawBufferIndexes[count] != bufIndex) {
 388             fb->_ColorDrawBufferIndexes[count] = bufIndex;
 389             newState = GL_TRUE;
 390          }
 391          count++;
 392          destMask0 &= ~(1 << bufIndex);
 393       }
 394       fb->ColorDrawBuffer[0] = buffers[0];
 395       if (fb->_NumColorDrawBuffers != count) {
 396          fb->_NumColorDrawBuffers = count;
 397          newState = GL_TRUE;
 398       }
 399    }
 400    else {
 401       GLuint buf, count = 0;
 402       for (buf = 0; buf < n; buf++ ) {
 403          if (destMask[buf]) {
 404             GLint bufIndex = _mesa_ffs(destMask[buf]) - 1;
 405             /* only one bit should be set in the destMask[buf] field */
 406             ASSERT(_mesa_bitcount(destMask[buf]) == 1);
 407             if (fb->_ColorDrawBufferIndexes[buf] != bufIndex) {
 408                fb->_ColorDrawBufferIndexes[buf] = bufIndex;
 409                newState = GL_TRUE;
 410             }
 411             fb->ColorDrawBuffer[buf] = buffers[buf];
 412             count = buf + 1;
 413          }
 414          else {
 415             if (fb->_ColorDrawBufferIndexes[buf] != -1) {
 416                fb->_ColorDrawBufferIndexes[buf] = -1;
 417                newState = GL_TRUE;
 418             }
 419          }
 420       }
 421       /* set remaining outputs to -1 (GL_NONE) */
 422       while (buf < ctx->Const.MaxDrawBuffers) {
 423          if (fb->_ColorDrawBufferIndexes[buf] != -1) {
 424             fb->_ColorDrawBufferIndexes[buf] = -1;
 425             newState = GL_TRUE;
 426          }
 427          fb->ColorDrawBuffer[buf] = GL_NONE;
 428          buf++;
 429       }
 430       fb->_NumColorDrawBuffers = count;
 431    }
 432
 433    if (fb->Name == 0) {
 434       /* also set context drawbuffer state */
 435       GLuint buf;
 436       for (buf = 0; buf < ctx->Const.MaxDrawBuffers; buf++) {
 437          if (ctx->Color.DrawBuffer[buf] != fb->ColorDrawBuffer[buf]) {
 438             ctx->Color.DrawBuffer[buf] = fb->ColorDrawBuffer[buf];
 439             newState = GL_TRUE;
 440          }
 441       }
 442    }
 443
 444    if (newState)
 445       FLUSH_VERTICES(ctx, _NEW_BUFFERS);
 446 }
 447
 448
 449 /**
 450  * Like \sa _mesa_drawbuffers(), this is a helper function for setting
 451  * GL_READ_BUFFER state in the context and current FBO.
 452  * \param ctx  the rendering context
 453  * \param buffer  GL_FRONT, GL_BACK, GL_COLOR_ATTACHMENT0, etc.
 454  * \param bufferIndex  the numerical index corresponding to 'buffer'
 455  */
 456 void
 457 _mesa_readbuffer(GLcontext *ctx, GLenum buffer, GLint bufferIndex)
 458 {
 459    struct gl_framebuffer *fb = ctx->ReadBuffer;
 460
 461    if (fb->Name == 0) {
 462       /* Only update the per-context READ_BUFFER state if we're bound to
 463        * a window-system framebuffer.
 464        */
 465       ctx->Pixel.ReadBuffer = buffer;
 466    }
 467
 468    fb->ColorReadBuffer = buffer;
 469    fb->_ColorReadBufferIndex = bufferIndex;
 470
 471    ctx->NewState |= _NEW_BUFFERS;
 472 }
 473
 474
 475
 476 /**
 477  * Called by glReadBuffer to set the source renderbuffer for reading pixels.
 478  * \param mode color buffer such as GL_FRONT, GL_BACK, etc.
 479  */
 480 void GLAPIENTRY
 481 _mesa_ReadBuffer(GLenum buffer)
 482 {
 483    struct gl_framebuffer *fb;
 484    GLbitfield supportedMask;
 485    GLint srcBuffer;
 486    GET_CURRENT_CONTEXT(ctx);
 487    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
 488
 489    if (MESA_VERBOSE & VERBOSE_API)
 490       _mesa_debug(ctx, "glReadBuffer %s\n", _mesa_lookup_enum_by_nr(buffer));
 491
 492    fb = ctx->ReadBuffer;
 493
 494    if (MESA_VERBOSE & VERBOSE_API)
 495       _mesa_debug(ctx, "glReadBuffer %s\n", _mesa_lookup_enum_by_nr(buffer));
 496
 497    if (fb->Name > 0 && buffer == GL_NONE) {
 498       /* This is legal for user-created framebuffer objects */
 499       srcBuffer = -1;
 500    }
 501    else {
 502       /* general case / window-system framebuffer */
 503       srcBuffer = read_buffer_enum_to_index(buffer);
 504       if (srcBuffer == -1) {
 505          _mesa_error(ctx, GL_INVALID_ENUM,
 506                      "glReadBuffer(buffer=0x%x)", buffer);
 507          return;
 508       }
 509       supportedMask = supported_buffer_bitmask(ctx, fb);
 510       if (((1 << srcBuffer) & supportedMask) == 0) {
 511          _mesa_error(ctx, GL_INVALID_OPERATION,
 512                      "glReadBuffer(buffer=0x%x)", buffer);
 513          return;
 514       }
 515    }
 516
 517    /* OK, all error checking has been completed now */
 518
 519    _mesa_readbuffer(ctx, buffer, srcBuffer);
 520    ctx->NewState |= _NEW_BUFFERS;
 521
 522    /*
 523     * Call device driver function.
 524     */
 525    if (ctx->Driver.ReadBuffer)
 526       (*ctx->Driver.ReadBuffer)(ctx, buffer);
 527 }