src/mesa/main/buffers.c

   1 /**
   2  * \file buffers.c
   3  * Frame buffer management.
   4  */
   5
   6 /*
   7  * Mesa 3-D graphics library
   8  * Version:  6.5
   9  *
  10  * Copyright (C) 1999-2005  Brian Paul   All Rights Reserved.
  11  *
  12  * Permission is hereby granted, free of charge, to any person obtaining a
  13  * copy of this software and associated documentation files (the "Software"),
  14  * to deal in the Software without restriction, including without limitation
  15  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  16  * and/or sell copies of the Software, and to permit persons to whom the
  17  * Software is furnished to do so, subject to the following conditions:
  18  *
  19  * The above copyright notice and this permission notice shall be included
  20  * in all copies or substantial portions of the Software.
  21  *
  22  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  23  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  25  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  26  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  27  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  28  */
  29
  30
  31 #include "glheader.h"
  32 #include "buffers.h"
  33 #include "colormac.h"
  34 #include "context.h"
  35 #include "enums.h"
  36 #include "fbobject.h"
  37 #include "state.h"
  38
  39
  40 #define BAD_MASK ~0u
  41
  42
  43 #if _HAVE_FULL_GL
  44 void GLAPIENTRY
  45 _mesa_ClearIndex( GLfloat c )
  46 {
  47    GET_CURRENT_CONTEXT(ctx);
  48    ASSERT_OUTSIDE_BEGIN_END(ctx);
  49
  50    if (ctx->Color.ClearIndex == (GLuint) c)
  51       return;
  52
  53    FLUSH_VERTICES(ctx, _NEW_COLOR);
  54    ctx->Color.ClearIndex = (GLuint) c;
  55
  56    if (!ctx->Visual.rgbMode && ctx->Driver.ClearIndex) {
  57       /* it's OK to call glClearIndex in RGBA mode but it should be a NOP */
  58       (*ctx->Driver.ClearIndex)( ctx, ctx->Color.ClearIndex );
  59    }
  60 }
  61 #endif
  62
  63
  64 /**
  65  * Specify the clear values for the color buffers.
  66  *
  67  * \param red red color component.
  68  * \param green green color component.
  69  * \param blue blue color component.
  70  * \param alpha alpha component.
  71  *
  72  * \sa glClearColor().
  73  *
  74  * Clamps the parameters and updates gl_colorbuffer_attrib::ClearColor.  On a
  75  * change, flushes the vertices and notifies the driver via the
  76  * dd_function_table::ClearColor callback.
  77  */
  78 void GLAPIENTRY
  79 _mesa_ClearColor( GLclampf red, GLclampf green, GLclampf blue, GLclampf alpha )
  80 {
  81    GLfloat tmp[4];
  82    GET_CURRENT_CONTEXT(ctx);
  83    ASSERT_OUTSIDE_BEGIN_END(ctx);
  84
  85    tmp[0] = CLAMP(red,   0.0F, 1.0F);
  86    tmp[1] = CLAMP(green, 0.0F, 1.0F);
  87    tmp[2] = CLAMP(blue,  0.0F, 1.0F);
  88    tmp[3] = CLAMP(alpha, 0.0F, 1.0F);
  89
  90    if (TEST_EQ_4V(tmp, ctx->Color.ClearColor))
  91       return; /* no change */
  92
  93    FLUSH_VERTICES(ctx, _NEW_COLOR);
  94    COPY_4V(ctx->Color.ClearColor, tmp);
  95
  96    if (ctx->Visual.rgbMode && ctx->Driver.ClearColor) {
  97       /* it's OK to call glClearColor in CI mode but it should be a NOP */
  98       (*ctx->Driver.ClearColor)(ctx, ctx->Color.ClearColor);
  99    }
 100 }
 101
 102
 103 /**
 104  * Clear buffers.
 105  *
 106  * \param mask bit-mask indicating the buffers to be cleared.
 107  *
 108  * Flushes the vertices and verifies the parameter. If __GLcontextRec::NewState
 109  * is set then calls _mesa_update_state() to update gl_frame_buffer::_Xmin,
 110  * etc. If the rasterization mode is set to GL_RENDER then requests the driver
 111  * to clear the buffers, via the dd_function_table::Clear callback.
 112  */
 113 void GLAPIENTRY
 114 _mesa_Clear( GLbitfield mask )
 115 {
 116    GET_CURRENT_CONTEXT(ctx);
 117    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
 118
 119    if (MESA_VERBOSE & VERBOSE_API)
 120       _mesa_debug(ctx, "glClear 0x%x\n", mask);
 121
 122    if (mask & ~(GL_COLOR_BUFFER_BIT |
 123                 GL_DEPTH_BUFFER_BIT |
 124                 GL_STENCIL_BUFFER_BIT |
 125                 GL_ACCUM_BUFFER_BIT)) {
 126       /* invalid bit set */
 127       _mesa_error( ctx, GL_INVALID_VALUE, "glClear(0x%x)", mask);
 128       return;
 129    }
 130
 131    if (ctx->NewState) {
 132       _mesa_update_state( ctx );        /* update _Xmin, etc */
 133    }
 134
 135    if (ctx->RenderMode == GL_RENDER) {
 136       const GLint x = ctx->DrawBuffer->_Xmin;
 137       const GLint y = ctx->DrawBuffer->_Ymin;
 138       const GLint height = ctx->DrawBuffer->_Ymax - ctx->DrawBuffer->_Ymin;
 139       const GLint width  = ctx->DrawBuffer->_Xmax - ctx->DrawBuffer->_Xmin;
 140       GLbitfield bufferMask;
 141
 142       /* don't clear depth buffer if depth writing disabled */
 143       if (!ctx->Depth.Mask)
 144          mask &= ~GL_DEPTH_BUFFER_BIT;
 145
 146       /* Build the bitmask to send to device driver's Clear function.
 147        * Note that the GL_COLOR_BUFFER_BIT flag will expand to 0, 1, 2 or 4
 148        * of the BUFFER_BIT_FRONT/BACK_LEFT/RIGHT flags, or one of the
 149        * BUFFER_BIT_COLORn flags.
 150        */
 151       bufferMask = 0;
 152       if (mask & GL_COLOR_BUFFER_BIT) {
 153          bufferMask |= ctx->DrawBuffer->_ColorDrawBufferMask[0];
 154       }
 155
 156       if ((mask & GL_DEPTH_BUFFER_BIT)
 157           && ctx->DrawBuffer->Visual.haveDepthBuffer) {
 158          bufferMask |= BUFFER_BIT_DEPTH;
 159       }
 160
 161       if ((mask & GL_STENCIL_BUFFER_BIT)
 162           && ctx->DrawBuffer->Visual.haveStencilBuffer) {
 163          bufferMask |= BUFFER_BIT_STENCIL;
 164       }
 165
 166       if ((mask & GL_ACCUM_BUFFER_BIT)
 167           && ctx->DrawBuffer->Visual.haveAccumBuffer) {
 168          bufferMask |= BUFFER_BIT_ACCUM;
 169       }
 170
 171       ASSERT(ctx->Driver.Clear);
 172       ctx->Driver.Clear( ctx, bufferMask, (GLboolean) !ctx->Scissor.Enabled,
 173                          x, y, width, height );
 174    }
 175 }
 176
 177
 178
 179 /**
 180  * Return bitmask of BUFFER_BIT_* flags indicating which color buffers are
 181  * available to the rendering context.
 182  * This depends on the framebuffer we're writing to.  For window system
 183  * framebuffers we look at the framebuffer's visual.  But for user-
 184  * create framebuffers we look at the number of supported color attachments.
 185  */
 186 static GLuint
 187 supported_buffer_bitmask(const GLcontext *ctx, GLuint framebufferID)
 188 {
 189    GLuint mask = 0x0;
 190    GLint i;
 191
 192    if (framebufferID > 0) {
 193       /* A user-created renderbuffer */
 194       ASSERT(ctx->Extensions.EXT_framebuffer_object);
 195       for (i = 0; i < ctx->Const.MaxColorAttachments; i++) {
 196          mask |= (BUFFER_BIT_COLOR0 << i);
 197       }
 198    }
 199    else {
 200       /* A window system renderbuffer */
 201       mask = BUFFER_BIT_FRONT_LEFT; /* always have this */
 202       if (ctx->Visual.stereoMode) {
 203          mask |= BUFFER_BIT_FRONT_RIGHT;
 204          if (ctx->Visual.doubleBufferMode) {
 205             mask |= BUFFER_BIT_BACK_LEFT | BUFFER_BIT_BACK_RIGHT;
 206          }
 207       }
 208       else if (ctx->Visual.doubleBufferMode) {
 209          mask |= BUFFER_BIT_BACK_LEFT;
 210       }
 211
 212       for (i = 0; i < ctx->Visual.numAuxBuffers; i++) {
 213          mask |= (BUFFER_BIT_AUX0 << i);
 214       }
 215    }
 216
 217    return mask;
 218 }
 219
 220
 221 /**
 222  * Helper routine used by glDrawBuffer and glDrawBuffersARB.
 223  * Given a GLenum naming one or more color buffers (such as
 224  * GL_FRONT_AND_BACK), return the corresponding bitmask of BUFFER_BIT_* flags.
 225  */
 226 static GLuint
 227 draw_buffer_enum_to_bitmask(GLenum buffer)
 228 {
 229    switch (buffer) {
 230       case GL_NONE:
 231          return 0;
 232       case GL_FRONT:
 233          return BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_FRONT_RIGHT;
 234       case GL_BACK:
 235          return BUFFER_BIT_BACK_LEFT | BUFFER_BIT_BACK_RIGHT;
 236       case GL_RIGHT:
 237          return BUFFER_BIT_FRONT_RIGHT | BUFFER_BIT_BACK_RIGHT;
 238       case GL_FRONT_RIGHT:
 239          return BUFFER_BIT_FRONT_RIGHT;
 240       case GL_BACK_RIGHT:
 241          return BUFFER_BIT_BACK_RIGHT;
 242       case GL_BACK_LEFT:
 243          return BUFFER_BIT_BACK_LEFT;
 244       case GL_FRONT_AND_BACK:
 245          return BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_BACK_LEFT
 246               | BUFFER_BIT_FRONT_RIGHT | BUFFER_BIT_BACK_RIGHT;
 247       case GL_LEFT:
 248          return BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_BACK_LEFT;
 249       case GL_FRONT_LEFT:
 250          return BUFFER_BIT_FRONT_LEFT;
 251       case GL_AUX0:
 252          return BUFFER_BIT_AUX0;
 253       case GL_AUX1:
 254          return BUFFER_BIT_AUX1;
 255       case GL_AUX2:
 256          return BUFFER_BIT_AUX2;
 257       case GL_AUX3:
 258          return BUFFER_BIT_AUX3;
 259       case GL_COLOR_ATTACHMENT0_EXT:
 260          return BUFFER_BIT_COLOR0;
 261       case GL_COLOR_ATTACHMENT1_EXT:
 262          return BUFFER_BIT_COLOR1;
 263       case GL_COLOR_ATTACHMENT2_EXT:
 264          return BUFFER_BIT_COLOR2;
 265       case GL_COLOR_ATTACHMENT3_EXT:
 266          return BUFFER_BIT_COLOR3;
 267       default:
 268          /* error */
 269          return BAD_MASK;
 270    }
 271 }
 272
 273
 274 /**
 275  * Helper routine used by glReadBuffer.
 276  * Given a GLenum naming (a) color buffer(s), return the corresponding
 277  * bitmask of DD_* flags.
 278  */
 279 static GLuint
 280 read_buffer_enum_to_bitmask(GLenum buffer)
 281 {
 282    switch (buffer) {
 283       case GL_FRONT:
 284          return BUFFER_BIT_FRONT_LEFT;
 285       case GL_BACK:
 286          return BUFFER_BIT_BACK_LEFT;
 287       case GL_RIGHT:
 288          return BUFFER_BIT_FRONT_RIGHT;
 289       case GL_FRONT_RIGHT:
 290          return BUFFER_BIT_FRONT_RIGHT;
 291       case GL_BACK_RIGHT:
 292          return BUFFER_BIT_BACK_RIGHT;
 293       case GL_BACK_LEFT:
 294          return BUFFER_BIT_BACK_LEFT;
 295       case GL_LEFT:
 296          return BUFFER_BIT_FRONT_LEFT;
 297       case GL_FRONT_LEFT:
 298          return BUFFER_BIT_FRONT_LEFT;
 299       case GL_AUX0:
 300          return BUFFER_BIT_AUX0;
 301       case GL_AUX1:
 302          return BUFFER_BIT_AUX1;
 303       case GL_AUX2:
 304          return BUFFER_BIT_AUX2;
 305       case GL_AUX3:
 306          return BUFFER_BIT_AUX3;
 307       case GL_COLOR_ATTACHMENT0_EXT:
 308          return BUFFER_BIT_COLOR0;
 309       case GL_COLOR_ATTACHMENT1_EXT:
 310          return BUFFER_BIT_COLOR1;
 311       case GL_COLOR_ATTACHMENT2_EXT:
 312          return BUFFER_BIT_COLOR2;
 313       case GL_COLOR_ATTACHMENT3_EXT:
 314          return BUFFER_BIT_COLOR3;
 315       default:
 316          /* error */
 317          return BAD_MASK;
 318    }
 319 }
 320
 321
 322 /**
 323  * Specify which color buffer(s) to draw into for the first color output.
 324  * Recall that fragment programs can write to multiple outputs.
 325  * \sa _mesa_DrawBuffersARB
 326  *
 327  * \param buffer  color buffer, such as GL_LEFT or GL_FRONT_AND_BACK.
 328  */
 329 void GLAPIENTRY
 330 _mesa_DrawBuffer(GLenum buffer)
 331 {
 332    GLuint bufferID;
 333    GLuint destMask;
 334    GET_CURRENT_CONTEXT(ctx);
 335    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx); /* too complex... */
 336
 337    if (MESA_VERBOSE & VERBOSE_API) {
 338       _mesa_debug(ctx, "glDrawBuffer %s\n", _mesa_lookup_enum_by_nr(buffer));
 339    }
 340
 341    bufferID = ctx->DrawBuffer->Name;
 342
 343    if (buffer == GL_NONE) {
 344       destMask = 0x0;
 345    }
 346    else {
 347       const GLuint supportedMask = supported_buffer_bitmask(ctx, bufferID);
 348       destMask = draw_buffer_enum_to_bitmask(buffer);
 349       if (destMask == BAD_MASK) {
 350          /* totally bogus buffer */
 351          _mesa_error(ctx, GL_INVALID_ENUM, "glDrawBuffer(buffer)");
 352          return;
 353       }
 354       destMask &= supportedMask;
 355       if (destMask == 0x0) {
 356          /* none of the named color buffers exist! */
 357          _mesa_error(ctx, GL_INVALID_OPERATION, "glDrawBuffer(buffer)");
 358          return;
 359       }
 360    }
 361
 362    /* if we get here, there's no error so set new state */
 363    _mesa_drawbuffers(ctx, 1, &buffer, &destMask);
 364 }
 365
 366
 367 /**
 368  * Called by glDrawBuffersARB; specifies the destination color buffers
 369  * for N fragment program color outputs.
 370  * \sa _mesa_DrawBuffer
 371  */
 372 void GLAPIENTRY
 373 _mesa_DrawBuffersARB(GLsizei n, const GLenum *buffers)
 374 {
 375    GLint output;
 376    GLuint usedBufferMask, supportedMask;
 377    GLuint bufferID;
 378    GLuint destMask[MAX_DRAW_BUFFERS];
 379    GET_CURRENT_CONTEXT(ctx);
 380    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
 381
 382    if (!ctx->Extensions.ARB_draw_buffers) {
 383       _mesa_error(ctx, GL_INVALID_OPERATION, "glDrawBuffersARB");
 384       return;
 385    }
 386    if (n < 1 || n > (GLsizei) ctx->Const.MaxDrawBuffers) {
 387       _mesa_error(ctx, GL_INVALID_VALUE, "glDrawBuffersARB(n)");
 388       return;
 389    }
 390
 391    bufferID = ctx->DrawBuffer->Name;
 392
 393    supportedMask = supported_buffer_bitmask(ctx, bufferID);
 394    usedBufferMask = 0x0;
 395
 396    /* complicated error checking... */
 397    for (output = 0; output < n; output++) {
 398       if (buffers[output] == GL_NONE) {
 399          destMask[output] = 0x0;
 400       }
 401       else {
 402          destMask[output] = draw_buffer_enum_to_bitmask(buffers[output]);
 403          if (destMask[output] == BAD_MASK
 404              || _mesa_bitcount(destMask[output]) > 1) {
 405             _mesa_error(ctx, GL_INVALID_ENUM, "glDrawBuffersARB(buffer)");
 406             return;
 407          }
 408          destMask[output] &= supportedMask;
 409          if (destMask[output] == 0) {
 410             _mesa_error(ctx, GL_INVALID_OPERATION,
 411                         "glDrawBuffersARB(unsupported buffer)");
 412             return;
 413          }
 414          if (destMask[output] & usedBufferMask) {
 415             /* can't specify a dest buffer more than once! */
 416             _mesa_error(ctx, GL_INVALID_OPERATION,
 417                         "glDrawBuffersARB(duplicated buffer)");
 418             return;
 419          }
 420
 421          /* update bitmask */
 422          usedBufferMask |= destMask[output];
 423       }
 424    }
 425
 426    /* OK, if we get here, there were no errors so set the new state */
 427    _mesa_drawbuffers(ctx, n, buffers, destMask);
 428 }
 429
 430
 431 /**
 432  * Set color output state.  Traditionally, there was only one color
 433  * output, but fragment programs can now have several distinct color
 434  * outputs (see GL_ARB_draw_buffers).  This function sets the state
 435  * for one such color output.
 436  */
 437 static void
 438 set_color_output(GLcontext *ctx, GLuint output, GLenum buffer, GLuint destMask)
 439 {
 440    struct gl_framebuffer *fb = ctx->DrawBuffer;
 441
 442    ASSERT(output < ctx->Const.MaxDrawBuffers);
 443
 444    fb->ColorDrawBuffer[output] = buffer;
 445    fb->_ColorDrawBufferMask[output] = destMask;
 446
 447    if (fb->Name == 0) {
 448       /* Set traditional state var */
 449       ctx->Color.DrawBuffer[output] = buffer;
 450    }
 451
 452    /* not really needed, will be set later */
 453    fb->_NumColorDrawBuffers[output] = 0;
 454 }
 455
 456
 457 /**
 458  * Helper routine used by _mesa_DrawBuffer, _mesa_DrawBuffersARB and
 459  * _mesa_PopAttrib to set drawbuffer state.
 460  */
 461 void
 462 _mesa_drawbuffers(GLcontext *ctx, GLsizei n, const GLenum *buffers,
 463                   const GLuint *destMask)
 464 {
 465    GLuint mask[MAX_DRAW_BUFFERS];
 466    GLint output;
 467
 468    if (!destMask) {
 469       /* compute destMask values now */
 470       const GLuint bufferID = ctx->DrawBuffer->Name;
 471       const GLuint supportedMask = supported_buffer_bitmask(ctx, bufferID);
 472       for (output = 0; output < n; output++) {
 473          mask[output] = draw_buffer_enum_to_bitmask(buffers[output]);
 474          ASSERT(mask[output] != BAD_MASK);
 475          mask[output] &= supportedMask;
 476       }
 477       destMask = mask;
 478    }
 479
 480    for (output = 0; output < n; output++) {
 481       set_color_output(ctx, output, buffers[output], destMask[output]);
 482    }
 483
 484    /* set remaining color outputs to NONE */
 485    for (output = n; output < ctx->Const.MaxDrawBuffers; output++) {
 486       set_color_output(ctx, output, GL_NONE, 0x0);
 487    }
 488
 489    ctx->NewState |= _NEW_COLOR;
 490
 491    /*
 492     * Call device driver function.
 493     */
 494    if (ctx->Driver.DrawBuffers)
 495       ctx->Driver.DrawBuffers(ctx, n, buffers);
 496    else if (ctx->Driver.DrawBuffer)
 497       ctx->Driver.DrawBuffer(ctx, buffers[0]);
 498 }
 499
 500
 501
 502 /**
 503  * Set the color buffer source for reading pixels.
 504  *
 505  * \param mode color buffer.
 506  *
 507  * \sa glReadBuffer().
 508  *
 509  */
 510 void GLAPIENTRY
 511 _mesa_ReadBuffer(GLenum buffer)
 512 {
 513    struct gl_framebuffer *fb;
 514    GLuint srcMask, supportedMask;
 515    GLuint bufferID;
 516    GET_CURRENT_CONTEXT(ctx);
 517    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
 518
 519    fb = ctx->ReadBuffer;
 520    bufferID = fb->Name;
 521
 522    if (MESA_VERBOSE & VERBOSE_API)
 523       _mesa_debug(ctx, "glReadBuffer %s\n", _mesa_lookup_enum_by_nr(buffer));
 524
 525    if (bufferID > 0 && buffer == GL_NONE) {
 526       /* legal! */
 527       srcMask = 0x0;
 528    }
 529    else {
 530       /* general case */
 531       srcMask = read_buffer_enum_to_bitmask(buffer);
 532       if (srcMask == BAD_MASK) {
 533          _mesa_error(ctx, GL_INVALID_ENUM, "glReadBuffer(buffer)");
 534          return;
 535       }
 536       supportedMask = supported_buffer_bitmask(ctx, bufferID);
 537       if ((srcMask & supportedMask) == 0) {
 538          _mesa_error(ctx, GL_INVALID_OPERATION, "glReadBuffer(buffer)");
 539          return;
 540       }
 541    }
 542
 543    if (bufferID == 0) {
 544       ctx->Pixel.ReadBuffer = buffer;
 545    }
 546    fb->ColorReadBuffer = buffer;
 547    fb->_ColorReadBufferMask = srcMask;
 548
 549    ctx->NewState |= _NEW_PIXEL;
 550
 551    /*
 552     * Call device driver function.
 553     */
 554    if (ctx->Driver.ReadBuffer)
 555       (*ctx->Driver.ReadBuffer)(ctx, buffer);
 556 }
 557
 558
 559 #if _HAVE_FULL_GL
 560
 561 /**
 562  * GL_MESA_resize_buffers extension.
 563  *
 564  * When this function is called, we'll ask the window system how large
 565  * the current window is.  If it's a new size, we'll call the driver's
 566  * ResizeBuffers function.  The driver will then resize its color buffers
 567  * as needed, and maybe call the swrast's routine for reallocating
 568  * swrast-managed depth/stencil/accum/etc buffers.
 569  * \note This function may be called from within Mesa or called by the
 570  * user directly (see the GL_MESA_resize_buffers extension).
 571  */
 572 void GLAPIENTRY
 573 _mesa_ResizeBuffersMESA( void )
 574 {
 575    GET_CURRENT_CONTEXT(ctx);
 576
 577    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH( ctx );
 578
 579    if (MESA_VERBOSE & VERBOSE_API)
 580       _mesa_debug(ctx, "glResizeBuffersMESA\n");
 581
 582    if (ctx->DrawBuffer && ctx->DrawBuffer->Name == 0) {
 583       GLuint newWidth, newHeight;
 584       GLframebuffer *buffer = ctx->DrawBuffer;
 585
 586       /* ask device driver for size of output buffer */
 587       ctx->Driver.GetBufferSize( buffer, &newWidth, &newHeight );
 588
 589       /* see if size of device driver's color buffer (window) has changed */
 590       if (buffer->Width != newWidth || buffer->Height != newHeight) {
 591          if (ctx->Driver.ResizeBuffers)
 592             ctx->Driver.ResizeBuffers(ctx, buffer, newWidth, newHeight );
 593       }
 594    }
 595
 596    if (ctx->ReadBuffer && ctx->ReadBuffer != ctx->DrawBuffer
 597        && ctx->ReadBuffer->Name == 0) {
 598       GLuint newWidth, newHeight;
 599       GLframebuffer *buffer = ctx->ReadBuffer;
 600
 601       /* ask device driver for size of read buffer */
 602       ctx->Driver.GetBufferSize( buffer, &newWidth, &newHeight );
 603
 604       /* see if size of device driver's color buffer (window) has changed */
 605       if (buffer->Width != newWidth || buffer->Height != newHeight) {
 606          if (ctx->Driver.ResizeBuffers)
 607             ctx->Driver.ResizeBuffers(ctx, buffer, newWidth, newHeight );
 608       }
 609    }
 610
 611    ctx->NewState |= _NEW_BUFFERS;  /* to update scissor / window bounds */
 612 }
 613
 614
 615 /*
 616  * XXX move somewhere else someday?
 617  */
 618 void GLAPIENTRY
 619 _mesa_SampleCoverageARB(GLclampf value, GLboolean invert)
 620 {
 621    GET_CURRENT_CONTEXT(ctx);
 622
 623    if (!ctx->Extensions.ARB_multisample) {
 624       _mesa_error(ctx, GL_INVALID_OPERATION, "glSampleCoverageARB");
 625       return;
 626    }
 627
 628    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH( ctx );
 629    ctx->Multisample.SampleCoverageValue = (GLfloat) CLAMP(value, 0.0, 1.0);
 630    ctx->Multisample.SampleCoverageInvert = invert;
 631    ctx->NewState |= _NEW_MULTISAMPLE;
 632 }
 633
 634 #endif /* _HAVE_FULL_GL */
 635
 636
 637
 638 /**
 639  * Define the scissor box.
 640  *
 641  * \param x, y coordinates of the scissor box lower-left corner.
 642  * \param width width of the scissor box.
 643  * \param height height of the scissor box.
 644  *
 645  * \sa glScissor().
 646  *
 647  * Verifies the parameters and updates __GLcontextRec::Scissor. On a
 648  * change flushes the vertices and notifies the driver via
 649  * the dd_function_table::Scissor callback.
 650  */
 651 void GLAPIENTRY
 652 _mesa_Scissor( GLint x, GLint y, GLsizei width, GLsizei height )
 653 {
 654    GET_CURRENT_CONTEXT(ctx);
 655    ASSERT_OUTSIDE_BEGIN_END(ctx);
 656
 657    if (width < 0 || height < 0) {
 658       _mesa_error( ctx, GL_INVALID_VALUE, "glScissor" );
 659       return;
 660    }
 661
 662    if (MESA_VERBOSE & VERBOSE_API)
 663       _mesa_debug(ctx, "glScissor %d %d %d %d\n", x, y, width, height);
 664
 665    if (x == ctx->Scissor.X &&
 666        y == ctx->Scissor.Y &&
 667        width == ctx->Scissor.Width &&
 668        height == ctx->Scissor.Height)
 669       return;
 670
 671    FLUSH_VERTICES(ctx, _NEW_SCISSOR);
 672    ctx->Scissor.X = x;
 673    ctx->Scissor.Y = y;
 674    ctx->Scissor.Width = width;
 675    ctx->Scissor.Height = height;
 676
 677    if (ctx->Driver.Scissor)
 678       ctx->Driver.Scissor( ctx, x, y, width, height );
 679 }
 680
 681
 682
 683 /**********************************************************************/
 684 /** \name Initialization */
 685 /*@{*/
 686
 687 /**
 688  * Initialize the context's scissor state.
 689  * \param ctx  the GL context.
 690  */
 691 void
 692 _mesa_init_scissor(GLcontext *ctx)
 693 {
 694    /* Scissor group */
 695    ctx->Scissor.Enabled = GL_FALSE;
 696    ctx->Scissor.X = 0;
 697    ctx->Scissor.Y = 0;
 698    ctx->Scissor.Width = 0;
 699    ctx->Scissor.Height = 0;
 700 }
 701
 702
 703 /**
 704  * Initialize the context's multisample state.
 705  * \param ctx  the GL context.
 706  */
 707 void
 708 _mesa_init_multisample(GLcontext *ctx)
 709 {
 710    ctx->Multisample.Enabled = GL_FALSE;
 711    ctx->Multisample.SampleAlphaToCoverage = GL_FALSE;
 712    ctx->Multisample.SampleAlphaToOne = GL_FALSE;
 713    ctx->Multisample.SampleCoverage = GL_FALSE;
 714    ctx->Multisample.SampleCoverageValue = 1.0;
 715    ctx->Multisample.SampleCoverageInvert = GL_FALSE;
 716 }
 717
 718 /*@}*/