src/mesa/main/clear.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 clear.c
  28  * glClearColor, glClearIndex, glClear() functions.
  29  */
  30
  31
  32
  33 #include "glheader.h"
  34 #include "clear.h"
  35 #include "context.h"
  36 #include "colormac.h"
  37 #include "enums.h"
  38 #include "macros.h"
  39 #include "mtypes.h"
  40 #include "state.h"
  41
  42
  43
  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
  57
  58 /**
  59  * Specify the clear values for the color buffers.
  60  *
  61  * \param red red color component.
  62  * \param green green color component.
  63  * \param blue blue color component.
  64  * \param alpha alpha component.
  65  *
  66  * \sa glClearColor().
  67  *
  68  * Clamps the parameters and updates gl_colorbuffer_attrib::ClearColor.  On a
  69  * change, flushes the vertices and notifies the driver via the
  70  * dd_function_table::ClearColor callback.
  71  */
  72 void GLAPIENTRY
  73 _mesa_ClearColor( GLclampf red, GLclampf green, GLclampf blue, GLclampf alpha )
  74 {
  75    GLfloat tmp[4];
  76    GET_CURRENT_CONTEXT(ctx);
  77    ASSERT_OUTSIDE_BEGIN_END(ctx);
  78
  79    tmp[0] = red;
  80    tmp[1] = green;
  81    tmp[2] = blue;
  82    tmp[3] = alpha;
  83
  84    if (TEST_EQ_4V(tmp, ctx->Color.ClearColor.f))
  85       return; /* no change */
  86
  87    FLUSH_VERTICES(ctx, _NEW_COLOR);
  88    COPY_4V(ctx->Color.ClearColor.f, tmp);
  89 }
  90
  91
  92 /**
  93  * GL_EXT_texture_integer
  94  */
  95 void GLAPIENTRY
  96 _mesa_ClearColorIiEXT(GLint r, GLint g, GLint b, GLint a)
  97 {
  98    GLint tmp[4];
  99    GET_CURRENT_CONTEXT(ctx);
 100    ASSERT_OUTSIDE_BEGIN_END(ctx);
 101
 102    tmp[0] = r;
 103    tmp[1] = g;
 104    tmp[2] = b;
 105    tmp[3] = a;
 106
 107    if (TEST_EQ_4V(tmp, ctx->Color.ClearColor.i))
 108       return; /* no change */
 109
 110    FLUSH_VERTICES(ctx, _NEW_COLOR);
 111    COPY_4V(ctx->Color.ClearColor.i, tmp);
 112 }
 113
 114
 115 /**
 116  * GL_EXT_texture_integer
 117  */
 118 void GLAPIENTRY
 119 _mesa_ClearColorIuiEXT(GLuint r, GLuint g, GLuint b, GLuint a)
 120 {
 121    GLuint tmp[4];
 122    GET_CURRENT_CONTEXT(ctx);
 123    ASSERT_OUTSIDE_BEGIN_END(ctx);
 124
 125    tmp[0] = r;
 126    tmp[1] = g;
 127    tmp[2] = b;
 128    tmp[3] = a;
 129
 130    if (TEST_EQ_4V(tmp, ctx->Color.ClearColor.ui))
 131       return; /* no change */
 132
 133    FLUSH_VERTICES(ctx, _NEW_COLOR);
 134    COPY_4V(ctx->Color.ClearColor.ui, tmp);
 135 }
 136
 137
 138 /**
 139  * Clear buffers.
 140  *
 141  * \param mask bit-mask indicating the buffers to be cleared.
 142  *
 143  * Flushes the vertices and verifies the parameter. If __struct gl_contextRec::NewState
 144  * is set then calls _mesa_update_state() to update gl_frame_buffer::_Xmin,
 145  * etc. If the rasterization mode is set to GL_RENDER then requests the driver
 146  * to clear the buffers, via the dd_function_table::Clear callback.
 147  */
 148 void GLAPIENTRY
 149 _mesa_Clear( GLbitfield mask )
 150 {
 151    GET_CURRENT_CONTEXT(ctx);
 152    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
 153
 154    FLUSH_CURRENT(ctx, 0);
 155
 156    if (MESA_VERBOSE & VERBOSE_API)
 157       _mesa_debug(ctx, "glClear 0x%x\n", mask);
 158
 159    if (mask & ~(GL_COLOR_BUFFER_BIT |
 160                 GL_DEPTH_BUFFER_BIT |
 161                 GL_STENCIL_BUFFER_BIT |
 162                 GL_ACCUM_BUFFER_BIT)) {
 163       /* invalid bit set */
 164       _mesa_error( ctx, GL_INVALID_VALUE, "glClear(0x%x)", mask);
 165       return;
 166    }
 167
 168    /* Accumulation buffers were removed in core contexts, and they never
 169     * existed in OpenGL ES.
 170     */
 171    if ((mask & GL_ACCUM_BUFFER_BIT) != 0
 172        && (ctx->API == API_OPENGL_CORE || _mesa_is_gles(ctx))) {
 173       _mesa_error( ctx, GL_INVALID_VALUE, "glClear(GL_ACCUM_BUFFER_BIT)");
 174       return;
 175    }
 176
 177    if (ctx->NewState) {
 178       _mesa_update_state( ctx );        /* update _Xmin, etc */
 179    }
 180
 181    if (ctx->DrawBuffer->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
 182       _mesa_error(ctx, GL_INVALID_FRAMEBUFFER_OPERATION_EXT,
 183                   "glClear(incomplete framebuffer)");
 184       return;
 185    }
 186
 187    if (ctx->DrawBuffer->Width == 0 || ctx->DrawBuffer->Height == 0 ||
 188        ctx->DrawBuffer->_Xmin >= ctx->DrawBuffer->_Xmax ||
 189        ctx->DrawBuffer->_Ymin >= ctx->DrawBuffer->_Ymax)
 190       return;
 191
 192    if (ctx->RasterDiscard)
 193       return;
 194
 195    if (ctx->RenderMode == GL_RENDER) {
 196       GLbitfield bufferMask;
 197
 198       /* don't clear depth buffer if depth writing disabled */
 199       if (!ctx->Depth.Mask)
 200          mask &= ~GL_DEPTH_BUFFER_BIT;
 201
 202       /* Build the bitmask to send to device driver's Clear function.
 203        * Note that the GL_COLOR_BUFFER_BIT flag will expand to 0, 1, 2 or 4
 204        * of the BUFFER_BIT_FRONT/BACK_LEFT/RIGHT flags, or one of the
 205        * BUFFER_BIT_COLORn flags.
 206        */
 207       bufferMask = 0;
 208       if (mask & GL_COLOR_BUFFER_BIT) {
 209          GLuint i;
 210          for (i = 0; i < ctx->DrawBuffer->_NumColorDrawBuffers; i++) {
 211             bufferMask |= (1 << ctx->DrawBuffer->_ColorDrawBufferIndexes[i]);
 212          }
 213       }
 214
 215       if ((mask & GL_DEPTH_BUFFER_BIT)
 216           && ctx->DrawBuffer->Visual.haveDepthBuffer) {
 217          bufferMask |= BUFFER_BIT_DEPTH;
 218       }
 219
 220       if ((mask & GL_STENCIL_BUFFER_BIT)
 221           && ctx->DrawBuffer->Visual.haveStencilBuffer) {
 222          bufferMask |= BUFFER_BIT_STENCIL;
 223       }
 224
 225       if ((mask & GL_ACCUM_BUFFER_BIT)
 226           && ctx->DrawBuffer->Visual.haveAccumBuffer) {
 227          bufferMask |= BUFFER_BIT_ACCUM;
 228       }
 229
 230       ASSERT(ctx->Driver.Clear);
 231       ctx->Driver.Clear(ctx, bufferMask);
 232    }
 233 }
 234
 235
 236 /** Returned by make_color_buffer_mask() for errors */
 237 #define INVALID_MASK ~0x0
 238
 239
 240 /**
 241  * Convert the glClearBuffer 'drawbuffer' parameter into a bitmask of
 242  * BUFFER_BIT_x values.
 243  * Return INVALID_MASK if the drawbuffer value is invalid.
 244  */
 245 static GLbitfield
 246 make_color_buffer_mask(struct gl_context *ctx, GLint drawbuffer)
 247 {
 248    const struct gl_renderbuffer_attachment *att = ctx->DrawBuffer->Attachment;
 249    GLbitfield mask = 0x0;
 250
 251    switch (drawbuffer) {
 252    case GL_FRONT:
 253       if (att[BUFFER_FRONT_LEFT].Renderbuffer)
 254          mask |= BUFFER_BIT_FRONT_LEFT;
 255       if (att[BUFFER_FRONT_RIGHT].Renderbuffer)
 256          mask |= BUFFER_BIT_FRONT_RIGHT;
 257       break;
 258    case GL_BACK:
 259       if (att[BUFFER_BACK_LEFT].Renderbuffer)
 260          mask |= BUFFER_BIT_BACK_LEFT;
 261       if (att[BUFFER_BACK_RIGHT].Renderbuffer)
 262          mask |= BUFFER_BIT_BACK_RIGHT;
 263       break;
 264    case GL_LEFT:
 265       if (att[BUFFER_FRONT_LEFT].Renderbuffer)
 266          mask |= BUFFER_BIT_FRONT_LEFT;
 267       if (att[BUFFER_BACK_LEFT].Renderbuffer)
 268          mask |= BUFFER_BIT_BACK_LEFT;
 269       break;
 270    case GL_RIGHT:
 271       if (att[BUFFER_FRONT_RIGHT].Renderbuffer)
 272          mask |= BUFFER_BIT_FRONT_RIGHT;
 273       if (att[BUFFER_BACK_RIGHT].Renderbuffer)
 274          mask |= BUFFER_BIT_BACK_RIGHT;
 275       break;
 276    case GL_FRONT_AND_BACK:
 277       if (att[BUFFER_FRONT_LEFT].Renderbuffer)
 278          mask |= BUFFER_BIT_FRONT_LEFT;
 279       if (att[BUFFER_BACK_LEFT].Renderbuffer)
 280          mask |= BUFFER_BIT_BACK_LEFT;
 281       if (att[BUFFER_FRONT_RIGHT].Renderbuffer)
 282          mask |= BUFFER_BIT_FRONT_RIGHT;
 283       if (att[BUFFER_BACK_RIGHT].Renderbuffer)
 284          mask |= BUFFER_BIT_BACK_RIGHT;
 285       break;
 286    default:
 287       if (drawbuffer < 0 || drawbuffer >= (GLint)ctx->Const.MaxDrawBuffers) {
 288          mask = INVALID_MASK;
 289       }
 290       else if (att[BUFFER_COLOR0 + drawbuffer].Renderbuffer) {
 291          mask |= (BUFFER_BIT_COLOR0 << drawbuffer);
 292       }
 293    }
 294
 295    return mask;
 296 }
 297
 298
 299
 300 /**
 301  * New in GL 3.0
 302  * Clear signed integer color buffer or stencil buffer (not depth).
 303  */
 304 void GLAPIENTRY
 305 _mesa_ClearBufferiv(GLenum buffer, GLint drawbuffer, const GLint *value)
 306 {
 307    GET_CURRENT_CONTEXT(ctx);
 308    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
 309
 310    FLUSH_CURRENT(ctx, 0);
 311
 312    if (ctx->NewState) {
 313       _mesa_update_state( ctx );
 314    }
 315
 316    switch (buffer) {
 317    case GL_STENCIL:
 318       /* Page 264 (page 280 of the PDF) of the OpenGL 3.0 spec says:
 319        *
 320        *     "ClearBuffer generates an INVALID VALUE error if buffer is
 321        *     COLOR and drawbuffer is less than zero, or greater than the
 322        *     value of MAX DRAW BUFFERS minus one; or if buffer is DEPTH,
 323        *     STENCIL, or DEPTH STENCIL and drawbuffer is not zero."
 324        */
 325       if (drawbuffer != 0) {
 326          _mesa_error(ctx, GL_INVALID_VALUE, "glClearBufferiv(drawbuffer=%d)",
 327                      drawbuffer);
 328          return;
 329       }
 330       else if (ctx->DrawBuffer->Attachment[BUFFER_STENCIL].Renderbuffer && !ctx->RasterDiscard) {
 331          /* Save current stencil clear value, set to 'value', do the
 332           * stencil clear and restore the clear value.
 333           * XXX in the future we may have a new ctx->Driver.ClearBuffer()
 334           * hook instead.
 335           */
 336          const GLuint clearSave = ctx->Stencil.Clear;
 337          ctx->Stencil.Clear = *value;
 338          ctx->Driver.Clear(ctx, BUFFER_BIT_STENCIL);
 339          ctx->Stencil.Clear = clearSave;
 340       }
 341       break;
 342    case GL_COLOR:
 343       {
 344          const GLbitfield mask = make_color_buffer_mask(ctx, drawbuffer);
 345          if (mask == INVALID_MASK) {
 346             _mesa_error(ctx, GL_INVALID_VALUE, "glClearBufferiv(drawbuffer=%d)",
 347                         drawbuffer);
 348             return;
 349          }
 350          else if (mask && !ctx->RasterDiscard) {
 351             union gl_color_union clearSave;
 352
 353             /* save color */
 354             clearSave = ctx->Color.ClearColor;
 355             /* set color */
 356             COPY_4V(ctx->Color.ClearColor.i, value);
 357             /* clear buffer(s) */
 358             ctx->Driver.Clear(ctx, mask);
 359             /* restore color */
 360             ctx->Color.ClearColor = clearSave;
 361          }
 362       }
 363       break;
 364    case GL_DEPTH:
 365       /* Page 264 (page 280 of the PDF) of the OpenGL 3.0 spec says:
 366        *
 367        *     "The result of ClearBuffer is undefined if no conversion between
 368        *     the type of the specified value and the type of the buffer being
 369        *     cleared is defined (for example, if ClearBufferiv is called for a
 370        *     fixed- or floating-point buffer, or if ClearBufferfv is called
 371        *     for a signed or unsigned integer buffer). This is not an error."
 372        *
 373        * In this case we take "undefined" and "not an error" to mean "ignore."
 374        * Note that we still need to generate an error for the invalid
 375        * drawbuffer case (see the GL_STENCIL case above).
 376        */
 377       if (drawbuffer != 0) {
 378          _mesa_error(ctx, GL_INVALID_VALUE, "glClearBufferiv(drawbuffer=%d)",
 379                      drawbuffer);
 380          return;
 381       }
 382       return;
 383    default:
 384       _mesa_error(ctx, GL_INVALID_ENUM, "glClearBufferiv(buffer=%s)",
 385                   _mesa_lookup_enum_by_nr(buffer));
 386       return;
 387    }
 388 }
 389
 390
 391 /**
 392  * New in GL 3.0
 393  * Clear unsigned integer color buffer (not depth, not stencil).
 394  */
 395 void GLAPIENTRY
 396 _mesa_ClearBufferuiv(GLenum buffer, GLint drawbuffer, const GLuint *value)
 397 {
 398    GET_CURRENT_CONTEXT(ctx);
 399    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
 400
 401    FLUSH_CURRENT(ctx, 0);
 402
 403    if (ctx->NewState) {
 404       _mesa_update_state( ctx );
 405    }
 406
 407    switch (buffer) {
 408    case GL_COLOR:
 409       {
 410          const GLbitfield mask = make_color_buffer_mask(ctx, drawbuffer);
 411          if (mask == INVALID_MASK) {
 412             _mesa_error(ctx, GL_INVALID_VALUE, "glClearBufferuiv(drawbuffer=%d)",
 413                         drawbuffer);
 414             return;
 415          }
 416          else if (mask && !ctx->RasterDiscard) {
 417             union gl_color_union clearSave;
 418
 419             /* save color */
 420             clearSave = ctx->Color.ClearColor;
 421             /* set color */
 422             COPY_4V(ctx->Color.ClearColor.ui, value);
 423             /* clear buffer(s) */
 424             ctx->Driver.Clear(ctx, mask);
 425             /* restore color */
 426             ctx->Color.ClearColor = clearSave;
 427          }
 428       }
 429       break;
 430    case GL_DEPTH:
 431    case GL_STENCIL:
 432       /* Page 264 (page 280 of the PDF) of the OpenGL 3.0 spec says:
 433        *
 434        *     "The result of ClearBuffer is undefined if no conversion between
 435        *     the type of the specified value and the type of the buffer being
 436        *     cleared is defined (for example, if ClearBufferiv is called for a
 437        *     fixed- or floating-point buffer, or if ClearBufferfv is called
 438        *     for a signed or unsigned integer buffer). This is not an error."
 439        *
 440        * In this case we take "undefined" and "not an error" to mean "ignore."
 441        * Even though we could do something sensible for GL_STENCIL, page 263
 442        * (page 279 of the PDF) says:
 443        *
 444        *     "Only ClearBufferiv should be used to clear stencil buffers."
 445        *
 446        * Note that we still need to generate an error for the invalid
 447        * drawbuffer case (see the GL_STENCIL case in _mesa_ClearBufferiv).
 448        */
 449       if (drawbuffer != 0) {
 450          _mesa_error(ctx, GL_INVALID_VALUE, "glClearBufferuiv(drawbuffer=%d)",
 451                      drawbuffer);
 452          return;
 453       }
 454       return;
 455    default:
 456       _mesa_error(ctx, GL_INVALID_ENUM, "glClearBufferuiv(buffer=%s)",
 457                   _mesa_lookup_enum_by_nr(buffer));
 458       return;
 459    }
 460 }
 461
 462
 463 /**
 464  * New in GL 3.0
 465  * Clear fixed-pt or float color buffer or depth buffer (not stencil).
 466  */
 467 void GLAPIENTRY
 468 _mesa_ClearBufferfv(GLenum buffer, GLint drawbuffer, const GLfloat *value)
 469 {
 470    GET_CURRENT_CONTEXT(ctx);
 471    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
 472
 473    FLUSH_CURRENT(ctx, 0);
 474
 475    if (ctx->NewState) {
 476       _mesa_update_state( ctx );
 477    }
 478
 479    switch (buffer) {
 480    case GL_DEPTH:
 481       /* Page 264 (page 280 of the PDF) of the OpenGL 3.0 spec says:
 482        *
 483        *     "ClearBuffer generates an INVALID VALUE error if buffer is
 484        *     COLOR and drawbuffer is less than zero, or greater than the
 485        *     value of MAX DRAW BUFFERS minus one; or if buffer is DEPTH,
 486        *     STENCIL, or DEPTH STENCIL and drawbuffer is not zero."
 487        */
 488       if (drawbuffer != 0) {
 489          _mesa_error(ctx, GL_INVALID_VALUE, "glClearBufferfv(drawbuffer=%d)",
 490                      drawbuffer);
 491          return;
 492       }
 493       else if (ctx->DrawBuffer->Attachment[BUFFER_DEPTH].Renderbuffer && !ctx->RasterDiscard) {
 494          /* Save current depth clear value, set to 'value', do the
 495           * depth clear and restore the clear value.
 496           * XXX in the future we may have a new ctx->Driver.ClearBuffer()
 497           * hook instead.
 498           */
 499          const GLclampd clearSave = ctx->Depth.Clear;
 500          ctx->Depth.Clear = *value;
 501          ctx->Driver.Clear(ctx, BUFFER_BIT_DEPTH);
 502          ctx->Depth.Clear = clearSave;
 503       }
 504       /* clear depth buffer to value */
 505       break;
 506    case GL_COLOR:
 507       {
 508          const GLbitfield mask = make_color_buffer_mask(ctx, drawbuffer);
 509          if (mask == INVALID_MASK) {
 510             _mesa_error(ctx, GL_INVALID_VALUE, "glClearBufferfv(drawbuffer=%d)",
 511                         drawbuffer);
 512             return;
 513          }
 514          else if (mask && !ctx->RasterDiscard) {
 515             union gl_color_union clearSave;
 516
 517             /* save color */
 518             clearSave = ctx->Color.ClearColor;
 519             /* set color */
 520             COPY_4V(ctx->Color.ClearColor.f, value);
 521             /* clear buffer(s) */
 522             ctx->Driver.Clear(ctx, mask);
 523             /* restore color */
 524             ctx->Color.ClearColor = clearSave;
 525          }
 526       }
 527       break;
 528    case GL_STENCIL:
 529       /* Page 264 (page 280 of the PDF) of the OpenGL 3.0 spec says:
 530        *
 531        *     "The result of ClearBuffer is undefined if no conversion between
 532        *     the type of the specified value and the type of the buffer being
 533        *     cleared is defined (for example, if ClearBufferiv is called for a
 534        *     fixed- or floating-point buffer, or if ClearBufferfv is called
 535        *     for a signed or unsigned integer buffer). This is not an error."
 536        *
 537        * In this case we take "undefined" and "not an error" to mean "ignore."
 538        * Note that we still need to generate an error for the invalid
 539        * drawbuffer case (see the GL_DEPTH case above).
 540        */
 541       if (drawbuffer != 0) {
 542          _mesa_error(ctx, GL_INVALID_VALUE, "glClearBufferfv(drawbuffer=%d)",
 543                      drawbuffer);
 544          return;
 545       }
 546       return;
 547    default:
 548       _mesa_error(ctx, GL_INVALID_ENUM, "glClearBufferfv(buffer=%s)",
 549                   _mesa_lookup_enum_by_nr(buffer));
 550       return;
 551    }
 552 }
 553
 554
 555 /**
 556  * New in GL 3.0
 557  * Clear depth/stencil buffer only.
 558  */
 559 void GLAPIENTRY
 560 _mesa_ClearBufferfi(GLenum buffer, GLint drawbuffer,
 561                     GLfloat depth, GLint stencil)
 562 {
 563    GET_CURRENT_CONTEXT(ctx);
 564    GLbitfield mask = 0;
 565
 566    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
 567
 568    FLUSH_CURRENT(ctx, 0);
 569
 570    if (buffer != GL_DEPTH_STENCIL) {
 571       _mesa_error(ctx, GL_INVALID_ENUM, "glClearBufferfi(buffer=%s)",
 572                   _mesa_lookup_enum_by_nr(buffer));
 573       return;
 574    }
 575
 576    /* Page 264 (page 280 of the PDF) of the OpenGL 3.0 spec says:
 577     *
 578     *     "ClearBuffer generates an INVALID VALUE error if buffer is
 579     *     COLOR and drawbuffer is less than zero, or greater than the
 580     *     value of MAX DRAW BUFFERS minus one; or if buffer is DEPTH,
 581     *     STENCIL, or DEPTH STENCIL and drawbuffer is not zero."
 582     */
 583    if (drawbuffer != 0) {
 584       _mesa_error(ctx, GL_INVALID_VALUE, "glClearBufferfi(drawbuffer=%d)",
 585                   drawbuffer);
 586       return;
 587    }
 588
 589    if (ctx->RasterDiscard)
 590       return;
 591
 592    if (ctx->NewState) {
 593       _mesa_update_state( ctx );
 594    }
 595
 596    if (ctx->DrawBuffer->Attachment[BUFFER_DEPTH].Renderbuffer)
 597       mask |= BUFFER_BIT_DEPTH;
 598    if (ctx->DrawBuffer->Attachment[BUFFER_STENCIL].Renderbuffer)
 599       mask |= BUFFER_BIT_STENCIL;
 600
 601    if (mask) {
 602       /* save current clear values */
 603       const GLclampd clearDepthSave = ctx->Depth.Clear;
 604       const GLuint clearStencilSave = ctx->Stencil.Clear;
 605
 606       /* set new clear values */
 607       ctx->Depth.Clear = depth;
 608       ctx->Stencil.Clear = stencil;
 609
 610       /* clear buffers */
 611       ctx->Driver.Clear(ctx, mask);
 612
 613       /* restore */
 614       ctx->Depth.Clear = clearDepthSave;
 615       ctx->Stencil.Clear = clearStencilSave;
 616    }
 617 }