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  * General framebuffer-related functions, like glClear, glScissor, etc.
  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 #if _HAVE_FULL_GL
  46 void GLAPIENTRY
  47 _mesa_ClearIndex( GLfloat c )
  48 {
  49    GET_CURRENT_CONTEXT(ctx);
  50    ASSERT_OUTSIDE_BEGIN_END(ctx);
  51
  52    if (ctx->Color.ClearIndex == (GLuint) c)
  53       return;
  54
  55    FLUSH_VERTICES(ctx, _NEW_COLOR);
  56    ctx->Color.ClearIndex = (GLuint) c;
  57
  58    if (!ctx->Visual.rgbMode && ctx->Driver.ClearIndex) {
  59       /* it's OK to call glClearIndex in RGBA mode but it should be a NOP */
  60       (*ctx->Driver.ClearIndex)( ctx, ctx->Color.ClearIndex );
  61    }
  62 }
  63 #endif
  64
  65
  66 /**
  67  * Specify the clear values for the color buffers.
  68  *
  69  * \param red red color component.
  70  * \param green green color component.
  71  * \param blue blue color component.
  72  * \param alpha alpha component.
  73  *
  74  * \sa glClearColor().
  75  *
  76  * Clamps the parameters and updates gl_colorbuffer_attrib::ClearColor.  On a
  77  * change, flushes the vertices and notifies the driver via the
  78  * dd_function_table::ClearColor callback.
  79  */
  80 void GLAPIENTRY
  81 _mesa_ClearColor( GLclampf red, GLclampf green, GLclampf blue, GLclampf alpha )
  82 {
  83    GLfloat tmp[4];
  84    GET_CURRENT_CONTEXT(ctx);
  85    ASSERT_OUTSIDE_BEGIN_END(ctx);
  86
  87    tmp[0] = CLAMP(red,   0.0F, 1.0F);
  88    tmp[1] = CLAMP(green, 0.0F, 1.0F);
  89    tmp[2] = CLAMP(blue,  0.0F, 1.0F);
  90    tmp[3] = CLAMP(alpha, 0.0F, 1.0F);
  91
  92    if (TEST_EQ_4V(tmp, ctx->Color.ClearColor))
  93       return; /* no change */
  94
  95    FLUSH_VERTICES(ctx, _NEW_COLOR);
  96    COPY_4V(ctx->Color.ClearColor, tmp);
  97
  98    if (ctx->Visual.rgbMode && ctx->Driver.ClearColor) {
  99       /* it's OK to call glClearColor in CI mode but it should be a NOP */
 100       (*ctx->Driver.ClearColor)(ctx, ctx->Color.ClearColor);
 101    }
 102 }
 103
 104
 105 /**
 106  * Clear buffers.
 107  *
 108  * \param mask bit-mask indicating the buffers to be cleared.
 109  *
 110  * Flushes the vertices and verifies the parameter. If __GLcontextRec::NewState
 111  * is set then calls _mesa_update_state() to update gl_frame_buffer::_Xmin,
 112  * etc. If the rasterization mode is set to GL_RENDER then requests the driver
 113  * to clear the buffers, via the dd_function_table::Clear callback.
 114  */
 115 void GLAPIENTRY
 116 _mesa_Clear( GLbitfield mask )
 117 {
 118    GET_CURRENT_CONTEXT(ctx);
 119    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
 120
 121    if (MESA_VERBOSE & VERBOSE_API)
 122       _mesa_debug(ctx, "glClear 0x%x\n", mask);
 123
 124    if (mask & ~(GL_COLOR_BUFFER_BIT |
 125                 GL_DEPTH_BUFFER_BIT |
 126                 GL_STENCIL_BUFFER_BIT |
 127                 GL_ACCUM_BUFFER_BIT)) {
 128       /* invalid bit set */
 129       _mesa_error( ctx, GL_INVALID_VALUE, "glClear(0x%x)", mask);
 130       return;
 131    }
 132
 133    if (ctx->NewState) {
 134       _mesa_update_state( ctx );        /* update _Xmin, etc */
 135    }
 136
 137    if (ctx->DrawBuffer->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
 138       _mesa_error(ctx, GL_INVALID_FRAMEBUFFER_OPERATION_EXT,
 139                   "glClear(incomplete framebuffer)");
 140       return;
 141    }
 142
 143    if (ctx->DrawBuffer->Width == 0 || ctx->DrawBuffer->Height == 0 ||
 144        ctx->DrawBuffer->_Xmin >= ctx->DrawBuffer->_Xmax ||
 145        ctx->DrawBuffer->_Ymin >= ctx->DrawBuffer->_Ymax)
 146       return;
 147
 148    if (ctx->RenderMode == GL_RENDER) {
 149       GLbitfield bufferMask;
 150
 151       /* don't clear depth buffer if depth writing disabled */
 152       if (!ctx->Depth.Mask)
 153          mask &= ~GL_DEPTH_BUFFER_BIT;
 154
 155       /* Build the bitmask to send to device driver's Clear function.
 156        * Note that the GL_COLOR_BUFFER_BIT flag will expand to 0, 1, 2 or 4
 157        * of the BUFFER_BIT_FRONT/BACK_LEFT/RIGHT flags, or one of the
 158        * BUFFER_BIT_COLORn flags.
 159        */
 160       bufferMask = 0;
 161       if (mask & GL_COLOR_BUFFER_BIT) {
 162          bufferMask |= ctx->DrawBuffer->_ColorDrawBufferMask[0];
 163       }
 164
 165       if ((mask & GL_DEPTH_BUFFER_BIT)
 166           && ctx->DrawBuffer->Visual.haveDepthBuffer) {
 167          bufferMask |= BUFFER_BIT_DEPTH;
 168       }
 169
 170       if ((mask & GL_STENCIL_BUFFER_BIT)
 171           && ctx->DrawBuffer->Visual.haveStencilBuffer) {
 172          bufferMask |= BUFFER_BIT_STENCIL;
 173       }
 174
 175       if ((mask & GL_ACCUM_BUFFER_BIT)
 176           && ctx->DrawBuffer->Visual.haveAccumBuffer) {
 177          bufferMask |= BUFFER_BIT_ACCUM;
 178       }
 179
 180       ASSERT(ctx->Driver.Clear);
 181       ctx->Driver.Clear(ctx, bufferMask);
 182    }
 183 }
 184
 185
 186
 187 /**
 188  * Return bitmask of BUFFER_BIT_* flags indicating which color buffers are
 189  * available to the rendering context (for drawing or reading).
 190  * This depends on the type of framebuffer.  For window system framebuffers
 191  * we look at the framebuffer's visual.  But for user-create framebuffers we
 192  * look at the number of supported color attachments.
 193  * \param fb  the framebuffer to draw to, or read from
 194  * \return  bitmask of BUFFER_BIT_* flags
 195  */
 196 static GLbitfield
 197 supported_buffer_bitmask(const GLcontext *ctx, const struct gl_framebuffer *fb)
 198 {
 199    GLbitfield mask = 0x0;
 200
 201    if (fb->Name > 0) {
 202       /* A user-created renderbuffer */
 203       GLuint i;
 204       ASSERT(ctx->Extensions.EXT_framebuffer_object);
 205       for (i = 0; i < ctx->Const.MaxColorAttachments; i++) {
 206          mask |= (BUFFER_BIT_COLOR0 << i);
 207       }
 208    }
 209    else {
 210       /* A window system framebuffer */
 211       GLint i;
 212       mask = BUFFER_BIT_FRONT_LEFT; /* always have this */
 213       if (fb->Visual.stereoMode) {
 214          mask |= BUFFER_BIT_FRONT_RIGHT;
 215          if (fb->Visual.doubleBufferMode) {
 216             mask |= BUFFER_BIT_BACK_LEFT | BUFFER_BIT_BACK_RIGHT;
 217          }
 218       }
 219       else if (fb->Visual.doubleBufferMode) {
 220          mask |= BUFFER_BIT_BACK_LEFT;
 221       }
 222
 223       for (i = 0; i < fb->Visual.numAuxBuffers; i++) {
 224          mask |= (BUFFER_BIT_AUX0 << i);
 225       }
 226    }
 227
 228    return mask;
 229 }
 230
 231
 232 /**
 233  * Helper routine used by glDrawBuffer and glDrawBuffersARB.
 234  * Given a GLenum naming one or more color buffers (such as
 235  * GL_FRONT_AND_BACK), return the corresponding bitmask of BUFFER_BIT_* flags.
 236  */
 237 static GLbitfield
 238 draw_buffer_enum_to_bitmask(GLenum buffer)
 239 {
 240    switch (buffer) {
 241       case GL_NONE:
 242          return 0;
 243       case GL_FRONT:
 244          return BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_FRONT_RIGHT;
 245       case GL_BACK:
 246          return BUFFER_BIT_BACK_LEFT | BUFFER_BIT_BACK_RIGHT;
 247       case GL_RIGHT:
 248          return BUFFER_BIT_FRONT_RIGHT | BUFFER_BIT_BACK_RIGHT;
 249       case GL_FRONT_RIGHT:
 250          return BUFFER_BIT_FRONT_RIGHT;
 251       case GL_BACK_RIGHT:
 252          return BUFFER_BIT_BACK_RIGHT;
 253       case GL_BACK_LEFT:
 254          return BUFFER_BIT_BACK_LEFT;
 255       case GL_FRONT_AND_BACK:
 256          return BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_BACK_LEFT
 257               | BUFFER_BIT_FRONT_RIGHT | BUFFER_BIT_BACK_RIGHT;
 258       case GL_LEFT:
 259          return BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_BACK_LEFT;
 260       case GL_FRONT_LEFT:
 261          return BUFFER_BIT_FRONT_LEFT;
 262       case GL_AUX0:
 263          return BUFFER_BIT_AUX0;
 264       case GL_AUX1:
 265          return BUFFER_BIT_AUX1;
 266       case GL_AUX2:
 267          return BUFFER_BIT_AUX2;
 268       case GL_AUX3:
 269          return BUFFER_BIT_AUX3;
 270       case GL_COLOR_ATTACHMENT0_EXT:
 271          return BUFFER_BIT_COLOR0;
 272       case GL_COLOR_ATTACHMENT1_EXT:
 273          return BUFFER_BIT_COLOR1;
 274       case GL_COLOR_ATTACHMENT2_EXT:
 275          return BUFFER_BIT_COLOR2;
 276       case GL_COLOR_ATTACHMENT3_EXT:
 277          return BUFFER_BIT_COLOR3;
 278       default:
 279          /* error */
 280          return BAD_MASK;
 281    }
 282 }
 283
 284
 285 /**
 286  * Helper routine used by glReadBuffer.
 287  * Given a GLenum naming a color buffer, return the index of the corresponding
 288  * renderbuffer (a BUFFER_* value).
 289  * return -1 for an invalid buffer.
 290  */
 291 static GLint
 292 read_buffer_enum_to_index(GLenum buffer)
 293 {
 294    switch (buffer) {
 295       case GL_FRONT:
 296          return BUFFER_FRONT_LEFT;
 297       case GL_BACK:
 298          return BUFFER_BACK_LEFT;
 299       case GL_RIGHT:
 300          return BUFFER_FRONT_RIGHT;
 301       case GL_FRONT_RIGHT:
 302          return BUFFER_FRONT_RIGHT;
 303       case GL_BACK_RIGHT:
 304          return BUFFER_BACK_RIGHT;
 305       case GL_BACK_LEFT:
 306          return BUFFER_BACK_LEFT;
 307       case GL_LEFT:
 308          return BUFFER_FRONT_LEFT;
 309       case GL_FRONT_LEFT:
 310          return BUFFER_FRONT_LEFT;
 311       case GL_AUX0:
 312          return BUFFER_AUX0;
 313       case GL_AUX1:
 314          return BUFFER_AUX1;
 315       case GL_AUX2:
 316          return BUFFER_AUX2;
 317       case GL_AUX3:
 318          return BUFFER_AUX3;
 319       case GL_COLOR_ATTACHMENT0_EXT:
 320          return BUFFER_COLOR0;
 321       case GL_COLOR_ATTACHMENT1_EXT:
 322          return BUFFER_COLOR1;
 323       case GL_COLOR_ATTACHMENT2_EXT:
 324          return BUFFER_COLOR2;
 325       case GL_COLOR_ATTACHMENT3_EXT:
 326          return BUFFER_COLOR3;
 327       case GL_COLOR_ATTACHMENT4_EXT:
 328          return BUFFER_COLOR4;
 329       case GL_COLOR_ATTACHMENT5_EXT:
 330          return BUFFER_COLOR5;
 331       case GL_COLOR_ATTACHMENT6_EXT:
 332          return BUFFER_COLOR6;
 333       case GL_COLOR_ATTACHMENT7_EXT:
 334          return BUFFER_COLOR7;
 335       default:
 336          /* error */
 337          return -1;
 338    }
 339 }
 340
 341
 342 /**
 343  * Called by glDrawBuffer().
 344  * Specify which renderbuffer(s) to draw into for the first color output.
 345  * <buffer> can name zero, one, two or four renderbuffers!
 346  * \sa _mesa_DrawBuffersARB
 347  *
 348  * \param buffer  buffer token such as GL_LEFT or GL_FRONT_AND_BACK, etc.
 349  *
 350  * Note that the behaviour of this function depends on whether the
 351  * current ctx->DrawBuffer is a window-system framebuffer (Name=0) or
 352  * a user-created framebuffer object (Name!=0).
 353  *   In the former case, we update the per-context ctx->Color.DrawBuffer
 354  *   state var _and_ the FB's ColorDrawBuffer state.
 355  *   In the later case, we update the FB's ColorDrawBuffer state only.
 356  *
 357  * Furthermore, upon a MakeCurrent() or BindFramebuffer() call, if the
 358  * new FB is a window system FB, we need to re-update the FB's
 359  * ColorDrawBuffer state to match the context.  This is handled in
 360  * _mesa_update_framebuffer().
 361  *
 362  * See the GL_EXT_framebuffer_object spec for more info.
 363  */
 364 void GLAPIENTRY
 365 _mesa_DrawBuffer(GLenum buffer)
 366 {
 367    GLbitfield destMask;
 368    GET_CURRENT_CONTEXT(ctx);
 369    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx); /* too complex... */
 370
 371    if (MESA_VERBOSE & VERBOSE_API) {
 372       _mesa_debug(ctx, "glDrawBuffer %s\n", _mesa_lookup_enum_by_nr(buffer));
 373    }
 374
 375    if (buffer == GL_NONE) {
 376       destMask = 0x0;
 377    }
 378    else {
 379       const GLbitfield supportedMask
 380          = supported_buffer_bitmask(ctx, ctx->DrawBuffer);
 381       destMask = draw_buffer_enum_to_bitmask(buffer);
 382       if (destMask == BAD_MASK) {
 383          /* totally bogus buffer */
 384          _mesa_error(ctx, GL_INVALID_ENUM, "glDrawBuffer(buffer)");
 385          return;
 386       }
 387       destMask &= supportedMask;
 388       if (destMask == 0x0) {
 389          /* none of the named color buffers exist! */
 390          _mesa_error(ctx, GL_INVALID_OPERATION, "glDrawBuffer(buffer)");
 391          return;
 392       }
 393    }
 394
 395    /* if we get here, there's no error so set new state */
 396    _mesa_drawbuffers(ctx, 1, &buffer, &destMask);
 397
 398    /*
 399     * Call device driver function.
 400     */
 401    if (ctx->Driver.DrawBuffers)
 402       ctx->Driver.DrawBuffers(ctx, 1, &buffer);
 403    else if (ctx->Driver.DrawBuffer)
 404       ctx->Driver.DrawBuffer(ctx, buffer);
 405 }
 406
 407
 408 /**
 409  * Called by glDrawBuffersARB; specifies the destination color renderbuffers
 410  * for N fragment program color outputs.
 411  * \sa _mesa_DrawBuffer
 412  * \param n  number of outputs
 413  * \param buffers  array [n] of renderbuffer names.  Unlike glDrawBuffer, the
 414  *                 names cannot specify more than one buffer.  For example,
 415  *                 GL_FRONT_AND_BACK is illegal.
 416  */
 417 void GLAPIENTRY
 418 _mesa_DrawBuffersARB(GLsizei n, const GLenum *buffers)
 419 {
 420    GLint output;
 421    GLbitfield usedBufferMask, supportedMask;
 422    GLbitfield destMask[MAX_DRAW_BUFFERS];
 423    GET_CURRENT_CONTEXT(ctx);
 424    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
 425
 426    if (!ctx->Extensions.ARB_draw_buffers) {
 427       _mesa_error(ctx, GL_INVALID_OPERATION, "glDrawBuffersARB");
 428       return;
 429    }
 430    if (n < 1 || n > (GLsizei) ctx->Const.MaxDrawBuffers) {
 431       _mesa_error(ctx, GL_INVALID_VALUE, "glDrawBuffersARB(n)");
 432       return;
 433    }
 434
 435    supportedMask = supported_buffer_bitmask(ctx, ctx->DrawBuffer);
 436    usedBufferMask = 0x0;
 437
 438    /* complicated error checking... */
 439    for (output = 0; output < n; output++) {
 440       if (buffers[output] == GL_NONE) {
 441          destMask[output] = 0x0;
 442       }
 443       else {
 444          destMask[output] = draw_buffer_enum_to_bitmask(buffers[output]);
 445          if (destMask[output] == BAD_MASK
 446              || _mesa_bitcount(destMask[output]) > 1) {
 447             _mesa_error(ctx, GL_INVALID_ENUM, "glDrawBuffersARB(buffer)");
 448             return;
 449          }
 450          destMask[output] &= supportedMask;
 451          if (destMask[output] == 0) {
 452             _mesa_error(ctx, GL_INVALID_OPERATION,
 453                         "glDrawBuffersARB(unsupported buffer)");
 454             return;
 455          }
 456          if (destMask[output] & usedBufferMask) {
 457             /* can't specify a dest buffer more than once! */
 458             _mesa_error(ctx, GL_INVALID_OPERATION,
 459                         "glDrawBuffersARB(duplicated buffer)");
 460             return;
 461          }
 462
 463          /* update bitmask */
 464          usedBufferMask |= destMask[output];
 465       }
 466    }
 467
 468    /* OK, if we get here, there were no errors so set the new state */
 469    _mesa_drawbuffers(ctx, n, buffers, destMask);
 470
 471    /*
 472     * Call device driver function.
 473     */
 474    if (ctx->Driver.DrawBuffers)
 475       ctx->Driver.DrawBuffers(ctx, n, buffers);
 476    else if (ctx->Driver.DrawBuffer)
 477       ctx->Driver.DrawBuffer(ctx, buffers[0]);
 478 }
 479
 480
 481 /**
 482  * Set color output state.  Traditionally, there was only one color
 483  * output, but fragment programs can now have several distinct color
 484  * outputs (see GL_ARB_draw_buffers).  This function sets the state
 485  * for one such color output.
 486  * \param ctx  current context
 487  * \param output  which fragment program output
 488  * \param buffer  buffer to write to (like GL_LEFT)
 489  * \param destMask  BUFFER_* bitmask
 490  *                  (like BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_BACK_LEFT).
 491  */
 492 static void
 493 set_color_output(GLcontext *ctx, GLuint output, GLenum buffer,
 494                  GLbitfield destMask)
 495 {
 496    struct gl_framebuffer *fb = ctx->DrawBuffer;
 497
 498    ASSERT(output < ctx->Const.MaxDrawBuffers);
 499
 500    /* Set per-FBO state */
 501    fb->ColorDrawBuffer[output] = buffer;
 502    fb->_ColorDrawBufferMask[output] = destMask;
 503    /* not really needed, will be set later */
 504    fb->_NumColorDrawBuffers[output] = 0;
 505
 506    if (fb->Name == 0) {
 507       /* Only set the per-context DrawBuffer state if we're currently
 508        * drawing to a window system framebuffer.
 509        */
 510       ctx->Color.DrawBuffer[output] = buffer;
 511    }
 512 }
 513
 514
 515 /**
 516  * Helper function to set the GL_DRAW_BUFFER state in the context and
 517  * current FBO.
 518  *
 519  * All error checking will have been done prior to calling this function
 520  * so nothing should go wrong at this point.
 521  *
 522  * \param ctx  current context
 523  * \param n    number of color outputs to set
 524  * \param buffers  array[n] of colorbuffer names, like GL_LEFT.
 525  * \param destMask  array[n] of BUFFER_* bitmasks which correspond to the
 526  *                  colorbuffer names.  (i.e. GL_FRONT_AND_BACK =>
 527  *                  BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_BACK_LEFT).
 528  */
 529 void
 530 _mesa_drawbuffers(GLcontext *ctx, GLuint n, const GLenum *buffers,
 531                   const GLbitfield *destMask)
 532 {
 533    GLbitfield mask[MAX_DRAW_BUFFERS];
 534    GLuint output;
 535
 536    if (!destMask) {
 537       /* compute destMask values now */
 538       const GLbitfield supportedMask
 539          = supported_buffer_bitmask(ctx, ctx->DrawBuffer);
 540       for (output = 0; output < n; output++) {
 541          mask[output] = draw_buffer_enum_to_bitmask(buffers[output]);
 542          ASSERT(mask[output] != BAD_MASK);
 543          mask[output] &= supportedMask;
 544       }
 545       destMask = mask;
 546    }
 547
 548    for (output = 0; output < n; output++) {
 549       set_color_output(ctx, output, buffers[output], destMask[output]);
 550    }
 551
 552    /* set remaining color outputs to NONE */
 553    for (output = n; output < ctx->Const.MaxDrawBuffers; output++) {
 554       set_color_output(ctx, output, GL_NONE, 0x0);
 555    }
 556
 557    ctx->NewState |= _NEW_COLOR;
 558 }
 559
 560
 561 /**
 562  * Like \sa _mesa_drawbuffers(), this is a helper function for setting
 563  * GL_READ_BUFFER state in the context and current FBO.
 564  * \param ctx  the rendering context
 565  * \param buffer  GL_FRONT, GL_BACK, GL_COLOR_ATTACHMENT0, etc.
 566  * \param bufferIndex  the numerical index corresponding to 'buffer'
 567  */
 568 void
 569 _mesa_readbuffer(GLcontext *ctx, GLenum buffer, GLint bufferIndex)
 570 {
 571    struct gl_framebuffer *fb = ctx->ReadBuffer;
 572
 573    if (fb->Name == 0) {
 574       /* Only update the per-context READ_BUFFER state if we're bound to
 575        * a window-system framebuffer.
 576        */
 577       ctx->Pixel.ReadBuffer = buffer;
 578    }
 579
 580    fb->ColorReadBuffer = buffer;
 581    fb->_ColorReadBufferIndex = bufferIndex;
 582
 583    ctx->NewState |= _NEW_PIXEL;
 584 }
 585
 586
 587
 588 /**
 589  * Called by glReadBuffer to set the source renderbuffer for reading pixels.
 590  * \param mode color buffer such as GL_FRONT, GL_BACK, etc.
 591  */
 592 void GLAPIENTRY
 593 _mesa_ReadBuffer(GLenum buffer)
 594 {
 595    struct gl_framebuffer *fb;
 596    GLbitfield supportedMask;
 597    GLint srcBuffer;
 598    GET_CURRENT_CONTEXT(ctx);
 599    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
 600
 601    if (MESA_VERBOSE & VERBOSE_API)
 602       _mesa_debug(ctx, "glReadBuffer %s\n", _mesa_lookup_enum_by_nr(buffer));
 603
 604    fb = ctx->ReadBuffer;
 605
 606    if (MESA_VERBOSE & VERBOSE_API)
 607       _mesa_debug(ctx, "glReadBuffer %s\n", _mesa_lookup_enum_by_nr(buffer));
 608
 609    if (fb->Name > 0 && buffer == GL_NONE) {
 610       /* This is legal for user-created framebuffer objects */
 611       srcBuffer = -1;
 612    }
 613    else {
 614       /* general case / window-system framebuffer */
 615       srcBuffer = read_buffer_enum_to_index(buffer);
 616       if (srcBuffer == -1) {
 617          _mesa_error(ctx, GL_INVALID_ENUM,
 618                      "glReadBuffer(buffer=0x%x)", buffer);
 619          return;
 620       }
 621       supportedMask = supported_buffer_bitmask(ctx, fb);
 622       if (((1 << srcBuffer) & supportedMask) == 0) {
 623          _mesa_error(ctx, GL_INVALID_OPERATION,
 624                      "glReadBuffer(buffer=0x%x)", buffer);
 625          return;
 626       }
 627    }
 628
 629    /* OK, all error checking has been completed now */
 630
 631    _mesa_readbuffer(ctx, buffer, srcBuffer);
 632
 633    /*
 634     * Call device driver function.
 635     */
 636    if (ctx->Driver.ReadBuffer)
 637       (*ctx->Driver.ReadBuffer)(ctx, buffer);
 638 }
 639
 640
 641 #if _HAVE_FULL_GL
 642
 643 /**
 644  * XXX THIS IS OBSOLETE - drivers should take care of detecting window
 645  * size changes and act accordingly, likely calling _mesa_resize_framebuffer().
 646  *
 647  * GL_MESA_resize_buffers extension.
 648  *
 649  * When this function is called, we'll ask the window system how large
 650  * the current window is.  If it's a new size, we'll call the driver's
 651  * ResizeBuffers function.  The driver will then resize its color buffers
 652  * as needed, and maybe call the swrast's routine for reallocating
 653  * swrast-managed depth/stencil/accum/etc buffers.
 654  * \note This function should only be called through the GL API, not
 655  * from device drivers (as was done in the past).
 656  */
 657
 658 void _mesa_resizebuffers( GLcontext *ctx )
 659 {
 660    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH( ctx );
 661
 662    if (MESA_VERBOSE & VERBOSE_API)
 663       _mesa_debug(ctx, "glResizeBuffersMESA\n");
 664
 665    if (!ctx->Driver.GetBufferSize) {
 666       return;
 667    }
 668
 669    if (ctx->WinSysDrawBuffer) {
 670       GLuint newWidth, newHeight;
 671       GLframebuffer *buffer = ctx->WinSysDrawBuffer;
 672
 673       assert(buffer->Name == 0);
 674
 675       /* ask device driver for size of output buffer */
 676       ctx->Driver.GetBufferSize( buffer, &newWidth, &newHeight );
 677
 678       /* see if size of device driver's color buffer (window) has changed */
 679       if (buffer->Width != newWidth || buffer->Height != newHeight) {
 680          if (ctx->Driver.ResizeBuffers)
 681             ctx->Driver.ResizeBuffers(ctx, buffer, newWidth, newHeight );
 682       }
 683    }
 684
 685    if (ctx->WinSysReadBuffer
 686        && ctx->WinSysReadBuffer != ctx->WinSysDrawBuffer) {
 687       GLuint newWidth, newHeight;
 688       GLframebuffer *buffer = ctx->WinSysReadBuffer;
 689
 690       assert(buffer->Name == 0);
 691
 692       /* ask device driver for size of read buffer */
 693       ctx->Driver.GetBufferSize( buffer, &newWidth, &newHeight );
 694
 695       /* see if size of device driver's color buffer (window) has changed */
 696       if (buffer->Width != newWidth || buffer->Height != newHeight) {
 697          if (ctx->Driver.ResizeBuffers)
 698             ctx->Driver.ResizeBuffers(ctx, buffer, newWidth, newHeight );
 699       }
 700    }
 701
 702    ctx->NewState |= _NEW_BUFFERS;  /* to update scissor / window bounds */
 703 }
 704
 705
 706 /*
 707  * XXX THIS IS OBSOLETE
 708  */
 709 void GLAPIENTRY
 710 _mesa_ResizeBuffersMESA( void )
 711 {
 712    GET_CURRENT_CONTEXT(ctx);
 713
 714    if (ctx->Extensions.MESA_resize_buffers)
 715       _mesa_resizebuffers( ctx );
 716 }
 717
 718
 719 /*
 720  * XXX move somewhere else someday?
 721  */
 722 void GLAPIENTRY
 723 _mesa_SampleCoverageARB(GLclampf value, GLboolean invert)
 724 {
 725    GET_CURRENT_CONTEXT(ctx);
 726
 727    if (!ctx->Extensions.ARB_multisample) {
 728       _mesa_error(ctx, GL_INVALID_OPERATION, "glSampleCoverageARB");
 729       return;
 730    }
 731
 732    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH( ctx );
 733    ctx->Multisample.SampleCoverageValue = (GLfloat) CLAMP(value, 0.0, 1.0);
 734    ctx->Multisample.SampleCoverageInvert = invert;
 735    ctx->NewState |= _NEW_MULTISAMPLE;
 736 }
 737
 738 #endif /* _HAVE_FULL_GL */
 739
 740
 741
 742 /**
 743  * Define the scissor box.
 744  *
 745  * \param x, y coordinates of the scissor box lower-left corner.
 746  * \param width width of the scissor box.
 747  * \param height height of the scissor box.
 748  *
 749  * \sa glScissor().
 750  *
 751  * Verifies the parameters and updates __GLcontextRec::Scissor. On a
 752  * change flushes the vertices and notifies the driver via
 753  * the dd_function_table::Scissor callback.
 754  */
 755 void
 756 _mesa_set_scissor(GLcontext *ctx,
 757                   GLint x, GLint y, GLsizei width, GLsizei height)
 758 {
 759    if (x == ctx->Scissor.X &&
 760        y == ctx->Scissor.Y &&
 761        width == ctx->Scissor.Width &&
 762        height == ctx->Scissor.Height)
 763       return;
 764
 765    FLUSH_VERTICES(ctx, _NEW_SCISSOR);
 766    ctx->Scissor.X = x;
 767    ctx->Scissor.Y = y;
 768    ctx->Scissor.Width = width;
 769    ctx->Scissor.Height = height;
 770
 771    if (ctx->Driver.Scissor)
 772       ctx->Driver.Scissor( ctx, x, y, width, height );
 773 }
 774
 775
 776 void GLAPIENTRY
 777 _mesa_Scissor( GLint x, GLint y, GLsizei width, GLsizei height )
 778 {
 779    GET_CURRENT_CONTEXT(ctx);
 780    ASSERT_OUTSIDE_BEGIN_END(ctx);
 781
 782    if (width < 0 || height < 0) {
 783       _mesa_error( ctx, GL_INVALID_VALUE, "glScissor" );
 784       return;
 785    }
 786
 787    if (MESA_VERBOSE & VERBOSE_API)
 788       _mesa_debug(ctx, "glScissor %d %d %d %d\n", x, y, width, height);
 789
 790    _mesa_set_scissor(ctx, x, y, width, height);
 791 }
 792
 793
 794
 795 /**********************************************************************/
 796 /** \name Initialization */
 797 /*@{*/
 798
 799 /**
 800  * Initialize the context's scissor state.
 801  * \param ctx  the GL context.
 802  */
 803 void
 804 _mesa_init_scissor(GLcontext *ctx)
 805 {
 806    /* Scissor group */
 807    ctx->Scissor.Enabled = GL_FALSE;
 808    ctx->Scissor.X = 0;
 809    ctx->Scissor.Y = 0;
 810    ctx->Scissor.Width = 0;
 811    ctx->Scissor.Height = 0;
 812 }
 813
 814
 815 /**
 816  * Initialize the context's multisample state.
 817  * \param ctx  the GL context.
 818  */
 819 void
 820 _mesa_init_multisample(GLcontext *ctx)
 821 {
 822    ctx->Multisample.Enabled = GL_FALSE;
 823    ctx->Multisample.SampleAlphaToCoverage = GL_FALSE;
 824    ctx->Multisample.SampleAlphaToOne = GL_FALSE;
 825    ctx->Multisample.SampleCoverage = GL_FALSE;
 826    ctx->Multisample.SampleCoverageValue = 1.0;
 827    ctx->Multisample.SampleCoverageInvert = GL_FALSE;
 828 }
 829
 830 /*@}*/