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