src/mesa/main/blend.c

   1 /**
   2  * \file blend.c
   3  * Blending operations.
   4  */
   5
   6 /*
   7  * Mesa 3-D graphics library
   8  *
   9  * Copyright (C) 1999-2006  Brian Paul   All Rights Reserved.
  10  *
  11  * Permission is hereby granted, free of charge, to any person obtaining a
  12  * copy of this software and associated documentation files (the "Software"),
  13  * to deal in the Software without restriction, including without limitation
  14  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  15  * and/or sell copies of the Software, and to permit persons to whom the
  16  * Software is furnished to do so, subject to the following conditions:
  17  *
  18  * The above copyright notice and this permission notice shall be included
  19  * in all copies or substantial portions of the Software.
  20  *
  21  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  22  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  23  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  24  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  25  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  26  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  27  * OTHER DEALINGS IN THE SOFTWARE.
  28  */
  29
  30
  31
  32 #include "glheader.h"
  33 #include "blend.h"
  34 #include "context.h"
  35 #include "enums.h"
  36 #include "macros.h"
  37 #include "mtypes.h"
  38
  39
  40
  41 /**
  42  * Check if given blend source factor is legal.
  43  * \return GL_TRUE if legal, GL_FALSE otherwise.
  44  */
  45 static GLboolean
  46 legal_src_factor(const struct gl_context *ctx, GLenum factor)
  47 {
  48    switch (factor) {
  49    case GL_SRC_COLOR:
  50    case GL_ONE_MINUS_SRC_COLOR:
  51    case GL_ZERO:
  52    case GL_ONE:
  53    case GL_DST_COLOR:
  54    case GL_ONE_MINUS_DST_COLOR:
  55    case GL_SRC_ALPHA:
  56    case GL_ONE_MINUS_SRC_ALPHA:
  57    case GL_DST_ALPHA:
  58    case GL_ONE_MINUS_DST_ALPHA:
  59    case GL_SRC_ALPHA_SATURATE:
  60       return GL_TRUE;
  61    case GL_CONSTANT_COLOR:
  62    case GL_ONE_MINUS_CONSTANT_COLOR:
  63    case GL_CONSTANT_ALPHA:
  64    case GL_ONE_MINUS_CONSTANT_ALPHA:
  65       return _mesa_is_desktop_gl(ctx) || ctx->API == API_OPENGLES2;
  66    case GL_SRC1_COLOR:
  67    case GL_SRC1_ALPHA:
  68    case GL_ONE_MINUS_SRC1_COLOR:
  69    case GL_ONE_MINUS_SRC1_ALPHA:
  70       return ctx->API != API_OPENGLES
  71          && ctx->Extensions.ARB_blend_func_extended;
  72    default:
  73       return GL_FALSE;
  74    }
  75 }
  76
  77
  78 /**
  79  * Check if given blend destination factor is legal.
  80  * \return GL_TRUE if legal, GL_FALSE otherwise.
  81  */
  82 static GLboolean
  83 legal_dst_factor(const struct gl_context *ctx, GLenum factor)
  84 {
  85    switch (factor) {
  86    case GL_DST_COLOR:
  87    case GL_ONE_MINUS_DST_COLOR:
  88    case GL_ZERO:
  89    case GL_ONE:
  90    case GL_SRC_COLOR:
  91    case GL_ONE_MINUS_SRC_COLOR:
  92    case GL_SRC_ALPHA:
  93    case GL_ONE_MINUS_SRC_ALPHA:
  94    case GL_DST_ALPHA:
  95    case GL_ONE_MINUS_DST_ALPHA:
  96       return GL_TRUE;
  97    case GL_CONSTANT_COLOR:
  98    case GL_ONE_MINUS_CONSTANT_COLOR:
  99    case GL_CONSTANT_ALPHA:
 100    case GL_ONE_MINUS_CONSTANT_ALPHA:
 101       return _mesa_is_desktop_gl(ctx) || ctx->API == API_OPENGLES2;
 102    case GL_SRC_ALPHA_SATURATE:
 103       return (ctx->API != API_OPENGLES
 104               && ctx->Extensions.ARB_blend_func_extended)
 105          || _mesa_is_gles3(ctx);
 106    case GL_SRC1_COLOR:
 107    case GL_SRC1_ALPHA:
 108    case GL_ONE_MINUS_SRC1_COLOR:
 109    case GL_ONE_MINUS_SRC1_ALPHA:
 110       return ctx->API != API_OPENGLES
 111          && ctx->Extensions.ARB_blend_func_extended;
 112    default:
 113       return GL_FALSE;
 114    }
 115 }
 116
 117
 118 /**
 119  * Check if src/dest RGB/A blend factors are legal.  If not generate
 120  * a GL error.
 121  * \return GL_TRUE if factors are legal, GL_FALSE otherwise.
 122  */
 123 static GLboolean
 124 validate_blend_factors(struct gl_context *ctx, const char *func,
 125                        GLenum sfactorRGB, GLenum dfactorRGB,
 126                        GLenum sfactorA, GLenum dfactorA)
 127 {
 128    if (!legal_src_factor(ctx, sfactorRGB)) {
 129       _mesa_error(ctx, GL_INVALID_ENUM,
 130                   "%s(sfactorRGB = %s)", func,
 131                   _mesa_enum_to_string(sfactorRGB));
 132       return GL_FALSE;
 133    }
 134
 135    if (!legal_dst_factor(ctx, dfactorRGB)) {
 136       _mesa_error(ctx, GL_INVALID_ENUM,
 137                   "%s(dfactorRGB = %s)", func,
 138                   _mesa_enum_to_string(dfactorRGB));
 139       return GL_FALSE;
 140    }
 141
 142    if (sfactorA != sfactorRGB && !legal_src_factor(ctx, sfactorA)) {
 143       _mesa_error(ctx, GL_INVALID_ENUM,
 144                   "%s(sfactorA = %s)", func,
 145                   _mesa_enum_to_string(sfactorA));
 146       return GL_FALSE;
 147    }
 148
 149    if (dfactorA != dfactorRGB && !legal_dst_factor(ctx, dfactorA)) {
 150       _mesa_error(ctx, GL_INVALID_ENUM,
 151                   "%s(dfactorA = %s)", func,
 152                   _mesa_enum_to_string(dfactorA));
 153       return GL_FALSE;
 154    }
 155
 156    return GL_TRUE;
 157 }
 158
 159
 160 static GLboolean
 161 blend_factor_is_dual_src(GLenum factor)
 162 {
 163    return (factor == GL_SRC1_COLOR ||
 164            factor == GL_SRC1_ALPHA ||
 165            factor == GL_ONE_MINUS_SRC1_COLOR ||
 166            factor == GL_ONE_MINUS_SRC1_ALPHA);
 167 }
 168
 169 static void
 170 update_uses_dual_src(struct gl_context *ctx, int buf)
 171 {
 172    ctx->Color.Blend[buf]._UsesDualSrc =
 173       (blend_factor_is_dual_src(ctx->Color.Blend[buf].SrcRGB) ||
 174        blend_factor_is_dual_src(ctx->Color.Blend[buf].DstRGB) ||
 175        blend_factor_is_dual_src(ctx->Color.Blend[buf].SrcA) ||
 176        blend_factor_is_dual_src(ctx->Color.Blend[buf].DstA));
 177 }
 178
 179
 180 /**
 181  * Return the number of per-buffer blend states to update in
 182  * glBlendFunc, glBlendFuncSeparate, glBlendEquation, etc.
 183  */
 184 static inline unsigned
 185 num_buffers(const struct gl_context *ctx)
 186 {
 187    return ctx->Extensions.ARB_draw_buffers_blend
 188       ? ctx->Const.MaxDrawBuffers : 1;
 189 }
 190
 191
 192 /* Returns true if there was no change */
 193 static bool
 194 skip_blend_state_update(const struct gl_context *ctx,
 195                         GLenum sfactorRGB, GLenum dfactorRGB,
 196                         GLenum sfactorA, GLenum dfactorA)
 197 {
 198    /* Check if we're really changing any state.  If not, return early. */
 199    if (ctx->Color._BlendFuncPerBuffer) {
 200       const unsigned numBuffers = num_buffers(ctx);
 201
 202       /* Check all per-buffer states */
 203       for (unsigned buf = 0; buf < numBuffers; buf++) {
 204          if (ctx->Color.Blend[buf].SrcRGB != sfactorRGB ||
 205              ctx->Color.Blend[buf].DstRGB != dfactorRGB ||
 206              ctx->Color.Blend[buf].SrcA != sfactorA ||
 207              ctx->Color.Blend[buf].DstA != dfactorA) {
 208             return false;
 209          }
 210       }
 211    }
 212    else {
 213       /* only need to check 0th per-buffer state */
 214       if (ctx->Color.Blend[0].SrcRGB != sfactorRGB ||
 215           ctx->Color.Blend[0].DstRGB != dfactorRGB ||
 216           ctx->Color.Blend[0].SrcA != sfactorA ||
 217           ctx->Color.Blend[0].DstA != dfactorA) {
 218          return false;
 219       }
 220    }
 221
 222    return true;
 223 }
 224
 225
 226 static void
 227 blend_func_separate(struct gl_context *ctx,
 228                     GLenum sfactorRGB, GLenum dfactorRGB,
 229                     GLenum sfactorA, GLenum dfactorA)
 230 {
 231    FLUSH_VERTICES(ctx, ctx->DriverFlags.NewBlend ? 0 : _NEW_COLOR);
 232    ctx->NewDriverState |= ctx->DriverFlags.NewBlend;
 233
 234    const unsigned numBuffers = num_buffers(ctx);
 235    for (unsigned buf = 0; buf < numBuffers; buf++) {
 236       ctx->Color.Blend[buf].SrcRGB = sfactorRGB;
 237       ctx->Color.Blend[buf].DstRGB = dfactorRGB;
 238       ctx->Color.Blend[buf].SrcA = sfactorA;
 239       ctx->Color.Blend[buf].DstA = dfactorA;
 240    }
 241
 242    update_uses_dual_src(ctx, 0);
 243    for (unsigned buf = 1; buf < numBuffers; buf++) {
 244       ctx->Color.Blend[buf]._UsesDualSrc = ctx->Color.Blend[0]._UsesDualSrc;
 245    }
 246
 247    ctx->Color._BlendFuncPerBuffer = GL_FALSE;
 248
 249    if (ctx->Driver.BlendFuncSeparate) {
 250       ctx->Driver.BlendFuncSeparate(ctx, sfactorRGB, dfactorRGB,
 251                                     sfactorA, dfactorA);
 252    }
 253 }
 254
 255
 256 /**
 257  * Specify the blending operation.
 258  *
 259  * \param sfactor source factor operator.
 260  * \param dfactor destination factor operator.
 261  *
 262  * \sa glBlendFunc, glBlendFuncSeparateEXT
 263  */
 264 void GLAPIENTRY
 265 _mesa_BlendFunc( GLenum sfactor, GLenum dfactor )
 266 {
 267    GET_CURRENT_CONTEXT(ctx);
 268
 269    if (skip_blend_state_update(ctx, sfactor, dfactor, sfactor, dfactor))
 270       return;
 271
 272    if (!validate_blend_factors(ctx, "glBlendFunc",
 273                                sfactor, dfactor, sfactor, dfactor)) {
 274       return;
 275    }
 276
 277    blend_func_separate(ctx, sfactor, dfactor, sfactor, dfactor);
 278 }
 279
 280
 281 void GLAPIENTRY
 282 _mesa_BlendFunc_no_error(GLenum sfactor, GLenum dfactor)
 283 {
 284    GET_CURRENT_CONTEXT(ctx);
 285
 286    if (skip_blend_state_update(ctx, sfactor, dfactor, sfactor, dfactor))
 287       return;
 288
 289    blend_func_separate(ctx, sfactor, dfactor, sfactor, dfactor);
 290 }
 291
 292
 293 /**
 294  * Set the separate blend source/dest factors for all draw buffers.
 295  *
 296  * \param sfactorRGB RGB source factor operator.
 297  * \param dfactorRGB RGB destination factor operator.
 298  * \param sfactorA alpha source factor operator.
 299  * \param dfactorA alpha destination factor operator.
 300  */
 301 void GLAPIENTRY
 302 _mesa_BlendFuncSeparate( GLenum sfactorRGB, GLenum dfactorRGB,
 303                             GLenum sfactorA, GLenum dfactorA )
 304 {
 305    GET_CURRENT_CONTEXT(ctx);
 306
 307    if (MESA_VERBOSE & VERBOSE_API)
 308       _mesa_debug(ctx, "glBlendFuncSeparate %s %s %s %s\n",
 309                   _mesa_enum_to_string(sfactorRGB),
 310                   _mesa_enum_to_string(dfactorRGB),
 311                   _mesa_enum_to_string(sfactorA),
 312                   _mesa_enum_to_string(dfactorA));
 313
 314
 315
 316    if (skip_blend_state_update(ctx, sfactorRGB, dfactorRGB, sfactorA, dfactorA))
 317       return;
 318
 319    if (!validate_blend_factors(ctx, "glBlendFuncSeparate",
 320                                sfactorRGB, dfactorRGB,
 321                                sfactorA, dfactorA)) {
 322       return;
 323    }
 324
 325    blend_func_separate(ctx, sfactorRGB, dfactorRGB, sfactorA, dfactorA);
 326 }
 327
 328
 329 void GLAPIENTRY
 330 _mesa_BlendFuncSeparate_no_error(GLenum sfactorRGB, GLenum dfactorRGB,
 331                                  GLenum sfactorA, GLenum dfactorA)
 332 {
 333    GET_CURRENT_CONTEXT(ctx);
 334
 335    if (skip_blend_state_update(ctx, sfactorRGB, dfactorRGB, sfactorA, dfactorA))
 336       return;
 337
 338    blend_func_separate(ctx, sfactorRGB, dfactorRGB, sfactorA, dfactorA);
 339 }
 340
 341
 342 void GLAPIENTRY
 343 _mesa_BlendFunciARB_no_error(GLuint buf, GLenum sfactor, GLenum dfactor)
 344 {
 345    _mesa_BlendFuncSeparateiARB_no_error(buf, sfactor, dfactor, sfactor,
 346                                         dfactor);
 347 }
 348
 349
 350 /**
 351  * Set blend source/dest factors for one color buffer/target.
 352  */
 353 void GLAPIENTRY
 354 _mesa_BlendFunciARB(GLuint buf, GLenum sfactor, GLenum dfactor)
 355 {
 356    _mesa_BlendFuncSeparateiARB(buf, sfactor, dfactor, sfactor, dfactor);
 357 }
 358
 359
 360 static ALWAYS_INLINE void
 361 blend_func_separatei(GLuint buf, GLenum sfactorRGB, GLenum dfactorRGB,
 362                      GLenum sfactorA, GLenum dfactorA, bool no_error)
 363 {
 364    GET_CURRENT_CONTEXT(ctx);
 365
 366    if (!no_error) {
 367       if (!ctx->Extensions.ARB_draw_buffers_blend) {
 368          _mesa_error(ctx, GL_INVALID_OPERATION, "glBlendFunc[Separate]i()");
 369          return;
 370       }
 371
 372       if (buf >= ctx->Const.MaxDrawBuffers) {
 373          _mesa_error(ctx, GL_INVALID_VALUE, "glBlendFuncSeparatei(buffer=%u)",
 374                      buf);
 375          return;
 376       }
 377    }
 378
 379    if (ctx->Color.Blend[buf].SrcRGB == sfactorRGB &&
 380        ctx->Color.Blend[buf].DstRGB == dfactorRGB &&
 381        ctx->Color.Blend[buf].SrcA == sfactorA &&
 382        ctx->Color.Blend[buf].DstA == dfactorA)
 383       return; /* no change */
 384
 385    if (!no_error && !validate_blend_factors(ctx, "glBlendFuncSeparatei",
 386                                             sfactorRGB, dfactorRGB,
 387                                             sfactorA, dfactorA)) {
 388       return;
 389    }
 390
 391    FLUSH_VERTICES(ctx, ctx->DriverFlags.NewBlend ? 0 : _NEW_COLOR);
 392    ctx->NewDriverState |= ctx->DriverFlags.NewBlend;
 393
 394    ctx->Color.Blend[buf].SrcRGB = sfactorRGB;
 395    ctx->Color.Blend[buf].DstRGB = dfactorRGB;
 396    ctx->Color.Blend[buf].SrcA = sfactorA;
 397    ctx->Color.Blend[buf].DstA = dfactorA;
 398    update_uses_dual_src(ctx, buf);
 399    ctx->Color._BlendFuncPerBuffer = GL_TRUE;
 400 }
 401
 402
 403 void GLAPIENTRY
 404 _mesa_BlendFuncSeparateiARB_no_error(GLuint buf, GLenum sfactorRGB,
 405                                      GLenum dfactorRGB, GLenum sfactorA,
 406                                      GLenum dfactorA)
 407 {
 408    blend_func_separatei(buf, sfactorRGB, dfactorRGB, sfactorA, dfactorA,
 409                         true);
 410 }
 411
 412
 413 /**
 414  * Set separate blend source/dest factors for one color buffer/target.
 415  */
 416 void GLAPIENTRY
 417 _mesa_BlendFuncSeparateiARB(GLuint buf, GLenum sfactorRGB, GLenum dfactorRGB,
 418                             GLenum sfactorA, GLenum dfactorA)
 419 {
 420    blend_func_separatei(buf, sfactorRGB, dfactorRGB, sfactorA, dfactorA,
 421                         false);
 422 }
 423
 424
 425 /**
 426  * Return true if \p mode is a legal blending equation, excluding
 427  * GL_KHR_blend_equation_advanced modes.
 428  */
 429 static bool
 430 legal_simple_blend_equation(const struct gl_context *ctx, GLenum mode)
 431 {
 432    switch (mode) {
 433    case GL_FUNC_ADD:
 434    case GL_FUNC_SUBTRACT:
 435    case GL_FUNC_REVERSE_SUBTRACT:
 436       return GL_TRUE;
 437    case GL_MIN:
 438    case GL_MAX:
 439       return ctx->Extensions.EXT_blend_minmax;
 440    default:
 441       return GL_FALSE;
 442    }
 443 }
 444
 445 static enum gl_advanced_blend_mode
 446 advanced_blend_mode_from_gl_enum(GLenum mode)
 447 {
 448    switch (mode) {
 449    case GL_MULTIPLY_KHR:
 450       return BLEND_MULTIPLY;
 451    case GL_SCREEN_KHR:
 452       return BLEND_SCREEN;
 453    case GL_OVERLAY_KHR:
 454       return BLEND_OVERLAY;
 455    case GL_DARKEN_KHR:
 456       return BLEND_DARKEN;
 457    case GL_LIGHTEN_KHR:
 458       return BLEND_LIGHTEN;
 459    case GL_COLORDODGE_KHR:
 460       return BLEND_COLORDODGE;
 461    case GL_COLORBURN_KHR:
 462       return BLEND_COLORBURN;
 463    case GL_HARDLIGHT_KHR:
 464       return BLEND_HARDLIGHT;
 465    case GL_SOFTLIGHT_KHR:
 466       return BLEND_SOFTLIGHT;
 467    case GL_DIFFERENCE_KHR:
 468       return BLEND_DIFFERENCE;
 469    case GL_EXCLUSION_KHR:
 470       return BLEND_EXCLUSION;
 471    case GL_HSL_HUE_KHR:
 472       return BLEND_HSL_HUE;
 473    case GL_HSL_SATURATION_KHR:
 474       return BLEND_HSL_SATURATION;
 475    case GL_HSL_COLOR_KHR:
 476       return BLEND_HSL_COLOR;
 477    case GL_HSL_LUMINOSITY_KHR:
 478       return BLEND_HSL_LUMINOSITY;
 479    default:
 480       return BLEND_NONE;
 481    }
 482 }
 483
 484 /**
 485  * If \p mode is one of the advanced blending equations defined by
 486  * GL_KHR_blend_equation_advanced (and the extension is supported),
 487  * return the corresponding BLEND_* enum.  Otherwise, return BLEND_NONE
 488  * (which can also be treated as false).
 489  */
 490 static enum gl_advanced_blend_mode
 491 advanced_blend_mode(const struct gl_context *ctx, GLenum mode)
 492 {
 493    return _mesa_has_KHR_blend_equation_advanced(ctx) ?
 494           advanced_blend_mode_from_gl_enum(mode) : BLEND_NONE;
 495 }
 496
 497 /* This is really an extension function! */
 498 void GLAPIENTRY
 499 _mesa_BlendEquation( GLenum mode )
 500 {
 501    GET_CURRENT_CONTEXT(ctx);
 502    const unsigned numBuffers = num_buffers(ctx);
 503    unsigned buf;
 504    bool changed = false;
 505    enum gl_advanced_blend_mode advanced_mode = advanced_blend_mode(ctx, mode);
 506
 507    if (MESA_VERBOSE & VERBOSE_API)
 508       _mesa_debug(ctx, "glBlendEquation(%s)\n",
 509                   _mesa_enum_to_string(mode));
 510
 511    if (ctx->Color._BlendEquationPerBuffer) {
 512       /* Check all per-buffer states */
 513       for (buf = 0; buf < numBuffers; buf++) {
 514          if (ctx->Color.Blend[buf].EquationRGB != mode ||
 515              ctx->Color.Blend[buf].EquationA != mode) {
 516             changed = true;
 517             break;
 518          }
 519       }
 520    }
 521    else {
 522       /* only need to check 0th per-buffer state */
 523       if (ctx->Color.Blend[0].EquationRGB != mode ||
 524           ctx->Color.Blend[0].EquationA != mode) {
 525          changed = true;
 526       }
 527    }
 528
 529    if (!changed)
 530       return;
 531
 532
 533    if (!legal_simple_blend_equation(ctx, mode) && !advanced_mode) {
 534       _mesa_error(ctx, GL_INVALID_ENUM, "glBlendEquation");
 535       return;
 536    }
 537
 538    _mesa_flush_vertices_for_blend_state(ctx);
 539
 540    for (buf = 0; buf < numBuffers; buf++) {
 541       ctx->Color.Blend[buf].EquationRGB = mode;
 542       ctx->Color.Blend[buf].EquationA = mode;
 543    }
 544    ctx->Color._BlendEquationPerBuffer = GL_FALSE;
 545    ctx->Color._AdvancedBlendMode = advanced_mode;
 546
 547    if (ctx->Driver.BlendEquationSeparate)
 548       ctx->Driver.BlendEquationSeparate(ctx, mode, mode);
 549 }
 550
 551
 552 /**
 553  * Set blend equation for one color buffer/target.
 554  */
 555 static void
 556 blend_equationi(struct gl_context *ctx, GLuint buf, GLenum mode,
 557                 enum gl_advanced_blend_mode advanced_mode)
 558 {
 559    if (ctx->Color.Blend[buf].EquationRGB == mode &&
 560        ctx->Color.Blend[buf].EquationA == mode)
 561       return;  /* no change */
 562
 563    _mesa_flush_vertices_for_blend_state(ctx);
 564    ctx->Color.Blend[buf].EquationRGB = mode;
 565    ctx->Color.Blend[buf].EquationA = mode;
 566    ctx->Color._BlendEquationPerBuffer = GL_TRUE;
 567
 568    if (buf == 0)
 569       ctx->Color._AdvancedBlendMode = advanced_mode;
 570 }
 571
 572
 573 void GLAPIENTRY
 574 _mesa_BlendEquationiARB_no_error(GLuint buf, GLenum mode)
 575 {
 576    GET_CURRENT_CONTEXT(ctx);
 577
 578    enum gl_advanced_blend_mode advanced_mode = advanced_blend_mode(ctx, mode);
 579    blend_equationi(ctx, buf, mode, advanced_mode);
 580 }
 581
 582
 583 void GLAPIENTRY
 584 _mesa_BlendEquationiARB(GLuint buf, GLenum mode)
 585 {
 586    GET_CURRENT_CONTEXT(ctx);
 587    enum gl_advanced_blend_mode advanced_mode = advanced_blend_mode(ctx, mode);
 588
 589    if (MESA_VERBOSE & VERBOSE_API)
 590       _mesa_debug(ctx, "glBlendEquationi(%u, %s)\n",
 591                   buf, _mesa_enum_to_string(mode));
 592
 593    if (buf >= ctx->Const.MaxDrawBuffers) {
 594       _mesa_error(ctx, GL_INVALID_VALUE, "glBlendEquationi(buffer=%u)",
 595                   buf);
 596       return;
 597    }
 598
 599    if (!legal_simple_blend_equation(ctx, mode) && !advanced_mode) {
 600       _mesa_error(ctx, GL_INVALID_ENUM, "glBlendEquationi");
 601       return;
 602    }
 603
 604    blend_equationi(ctx, buf, mode, advanced_mode);
 605 }
 606
 607
 608 static void
 609 blend_equation_separate(struct gl_context *ctx, GLenum modeRGB, GLenum modeA,
 610                         bool no_error)
 611 {
 612    const unsigned numBuffers = num_buffers(ctx);
 613    unsigned buf;
 614    bool changed = false;
 615
 616    if (ctx->Color._BlendEquationPerBuffer) {
 617       /* Check all per-buffer states */
 618       for (buf = 0; buf < numBuffers; buf++) {
 619          if (ctx->Color.Blend[buf].EquationRGB != modeRGB ||
 620              ctx->Color.Blend[buf].EquationA != modeA) {
 621             changed = true;
 622             break;
 623          }
 624       }
 625    } else {
 626       /* only need to check 0th per-buffer state */
 627       if (ctx->Color.Blend[0].EquationRGB != modeRGB ||
 628           ctx->Color.Blend[0].EquationA != modeA) {
 629          changed = true;
 630       }
 631    }
 632
 633    if (!changed)
 634       return;
 635
 636    if (!no_error) {
 637       if ((modeRGB != modeA) && !ctx->Extensions.EXT_blend_equation_separate) {
 638          _mesa_error(ctx, GL_INVALID_OPERATION,
 639                      "glBlendEquationSeparateEXT not supported by driver");
 640          return;
 641       }
 642
 643       /* Only allow simple blending equations.
 644        * The GL_KHR_blend_equation_advanced spec says:
 645        *
 646        *    "NOTE: These enums are not accepted by the <modeRGB> or <modeAlpha>
 647        *     parameters of BlendEquationSeparate or BlendEquationSeparatei."
 648        */
 649       if (!legal_simple_blend_equation(ctx, modeRGB)) {
 650          _mesa_error(ctx, GL_INVALID_ENUM,
 651                      "glBlendEquationSeparateEXT(modeRGB)");
 652          return;
 653       }
 654
 655       if (!legal_simple_blend_equation(ctx, modeA)) {
 656          _mesa_error(ctx, GL_INVALID_ENUM, "glBlendEquationSeparateEXT(modeA)");
 657          return;
 658       }
 659    }
 660
 661    _mesa_flush_vertices_for_blend_state(ctx);
 662
 663    for (buf = 0; buf < numBuffers; buf++) {
 664       ctx->Color.Blend[buf].EquationRGB = modeRGB;
 665       ctx->Color.Blend[buf].EquationA = modeA;
 666    }
 667    ctx->Color._BlendEquationPerBuffer = GL_FALSE;
 668    ctx->Color._AdvancedBlendMode = BLEND_NONE;
 669
 670    if (ctx->Driver.BlendEquationSeparate)
 671       ctx->Driver.BlendEquationSeparate(ctx, modeRGB, modeA);
 672 }
 673
 674
 675 void GLAPIENTRY
 676 _mesa_BlendEquationSeparate(GLenum modeRGB, GLenum modeA)
 677 {
 678    GET_CURRENT_CONTEXT(ctx);
 679
 680    if (MESA_VERBOSE & VERBOSE_API)
 681       _mesa_debug(ctx, "glBlendEquationSeparateEXT(%s %s)\n",
 682                   _mesa_enum_to_string(modeRGB),
 683                   _mesa_enum_to_string(modeA));
 684
 685    blend_equation_separate(ctx, modeRGB, modeA, false);
 686 }
 687
 688
 689 static void
 690 blend_equation_separatei(struct gl_context *ctx, GLuint buf, GLenum modeRGB,
 691                          GLenum modeA)
 692 {
 693    if (ctx->Color.Blend[buf].EquationRGB == modeRGB &&
 694        ctx->Color.Blend[buf].EquationA == modeA)
 695       return;  /* no change */
 696
 697    _mesa_flush_vertices_for_blend_state(ctx);
 698    ctx->Color.Blend[buf].EquationRGB = modeRGB;
 699    ctx->Color.Blend[buf].EquationA = modeA;
 700    ctx->Color._BlendEquationPerBuffer = GL_TRUE;
 701    ctx->Color._AdvancedBlendMode = BLEND_NONE;
 702 }
 703
 704
 705 void GLAPIENTRY
 706 _mesa_BlendEquationSeparateiARB_no_error(GLuint buf, GLenum modeRGB,
 707                                          GLenum modeA)
 708 {
 709    GET_CURRENT_CONTEXT(ctx);
 710    blend_equation_separatei(ctx, buf, modeRGB, modeA);
 711 }
 712
 713
 714 /**
 715  * Set separate blend equations for one color buffer/target.
 716  */
 717 void GLAPIENTRY
 718 _mesa_BlendEquationSeparateiARB(GLuint buf, GLenum modeRGB, GLenum modeA)
 719 {
 720    GET_CURRENT_CONTEXT(ctx);
 721
 722    if (MESA_VERBOSE & VERBOSE_API)
 723       _mesa_debug(ctx, "glBlendEquationSeparatei(%u, %s %s)\n", buf,
 724                   _mesa_enum_to_string(modeRGB),
 725                   _mesa_enum_to_string(modeA));
 726
 727    if (buf >= ctx->Const.MaxDrawBuffers) {
 728       _mesa_error(ctx, GL_INVALID_VALUE, "glBlendEquationSeparatei(buffer=%u)",
 729                   buf);
 730       return;
 731    }
 732
 733    /* Only allow simple blending equations.
 734     * The GL_KHR_blend_equation_advanced spec says:
 735     *
 736     *    "NOTE: These enums are not accepted by the <modeRGB> or <modeAlpha>
 737     *     parameters of BlendEquationSeparate or BlendEquationSeparatei."
 738     */
 739    if (!legal_simple_blend_equation(ctx, modeRGB)) {
 740       _mesa_error(ctx, GL_INVALID_ENUM, "glBlendEquationSeparatei(modeRGB)");
 741       return;
 742    }
 743
 744    if (!legal_simple_blend_equation(ctx, modeA)) {
 745       _mesa_error(ctx, GL_INVALID_ENUM, "glBlendEquationSeparatei(modeA)");
 746       return;
 747    }
 748
 749    blend_equation_separatei(ctx, buf, modeRGB, modeA);
 750 }
 751
 752
 753 /**
 754  * Set the blending color.
 755  *
 756  * \param red red color component.
 757  * \param green green color component.
 758  * \param blue blue color component.
 759  * \param alpha alpha color component.
 760  *
 761  * \sa glBlendColor().
 762  *
 763  * Clamps the parameters and updates gl_colorbuffer_attrib::BlendColor.  On a
 764  * change, flushes the vertices and notifies the driver via
 765  * dd_function_table::BlendColor callback.
 766  */
 767 void GLAPIENTRY
 768 _mesa_BlendColor( GLclampf red, GLclampf green, GLclampf blue, GLclampf alpha )
 769 {
 770    GLfloat tmp[4];
 771    GET_CURRENT_CONTEXT(ctx);
 772
 773    tmp[0] = red;
 774    tmp[1] = green;
 775    tmp[2] = blue;
 776    tmp[3] = alpha;
 777
 778    if (TEST_EQ_4V(tmp, ctx->Color.BlendColorUnclamped))
 779       return;
 780
 781    FLUSH_VERTICES(ctx, ctx->DriverFlags.NewBlendColor ? 0 : _NEW_COLOR);
 782    ctx->NewDriverState |= ctx->DriverFlags.NewBlendColor;
 783    COPY_4FV( ctx->Color.BlendColorUnclamped, tmp );
 784
 785    ctx->Color.BlendColor[0] = CLAMP(tmp[0], 0.0F, 1.0F);
 786    ctx->Color.BlendColor[1] = CLAMP(tmp[1], 0.0F, 1.0F);
 787    ctx->Color.BlendColor[2] = CLAMP(tmp[2], 0.0F, 1.0F);
 788    ctx->Color.BlendColor[3] = CLAMP(tmp[3], 0.0F, 1.0F);
 789
 790    if (ctx->Driver.BlendColor)
 791       ctx->Driver.BlendColor(ctx, ctx->Color.BlendColor);
 792 }
 793
 794
 795 /**
 796  * Specify the alpha test function.
 797  *
 798  * \param func alpha comparison function.
 799  * \param ref reference value.
 800  *
 801  * Verifies the parameters and updates gl_colorbuffer_attrib.
 802  * On a change, flushes the vertices and notifies the driver via
 803  * dd_function_table::AlphaFunc callback.
 804  */
 805 void GLAPIENTRY
 806 _mesa_AlphaFunc( GLenum func, GLclampf ref )
 807 {
 808    GET_CURRENT_CONTEXT(ctx);
 809
 810    if (MESA_VERBOSE & VERBOSE_API)
 811       _mesa_debug(ctx, "glAlphaFunc(%s, %f)\n",
 812                   _mesa_enum_to_string(func), ref);
 813
 814    if (ctx->Color.AlphaFunc == func && ctx->Color.AlphaRefUnclamped == ref)
 815       return; /* no change */
 816
 817    switch (func) {
 818    case GL_NEVER:
 819    case GL_LESS:
 820    case GL_EQUAL:
 821    case GL_LEQUAL:
 822    case GL_GREATER:
 823    case GL_NOTEQUAL:
 824    case GL_GEQUAL:
 825    case GL_ALWAYS:
 826       FLUSH_VERTICES(ctx, ctx->DriverFlags.NewAlphaTest ? 0 : _NEW_COLOR);
 827       ctx->NewDriverState |= ctx->DriverFlags.NewAlphaTest;
 828       ctx->Color.AlphaFunc = func;
 829       ctx->Color.AlphaRefUnclamped = ref;
 830       ctx->Color.AlphaRef = CLAMP(ref, 0.0F, 1.0F);
 831
 832       if (ctx->Driver.AlphaFunc)
 833          ctx->Driver.AlphaFunc(ctx, func, ctx->Color.AlphaRef);
 834       return;
 835
 836    default:
 837       _mesa_error( ctx, GL_INVALID_ENUM, "glAlphaFunc(func)" );
 838       return;
 839    }
 840 }
 841
 842
 843 static void
 844 logic_op(struct gl_context *ctx, GLenum opcode)
 845 {
 846    if (ctx->Color.LogicOp == opcode)
 847       return;
 848
 849    FLUSH_VERTICES(ctx, ctx->DriverFlags.NewLogicOp ? 0 : _NEW_COLOR);
 850    ctx->NewDriverState |= ctx->DriverFlags.NewLogicOp;
 851    ctx->Color.LogicOp = opcode;
 852
 853    if (ctx->Driver.LogicOpcode)
 854       ctx->Driver.LogicOpcode(ctx, opcode);
 855 }
 856
 857
 858 /**
 859  * Specify a logic pixel operation for color index rendering.
 860  *
 861  * \param opcode operation.
 862  *
 863  * Verifies that \p opcode is a valid enum and updates
 864  * gl_colorbuffer_attrib::LogicOp.
 865  * On a change, flushes the vertices and notifies the driver via the
 866  * dd_function_table::LogicOpcode callback.
 867  */
 868 void GLAPIENTRY
 869 _mesa_LogicOp( GLenum opcode )
 870 {
 871    GET_CURRENT_CONTEXT(ctx);
 872
 873    if (MESA_VERBOSE & VERBOSE_API)
 874       _mesa_debug(ctx, "glLogicOp(%s)\n", _mesa_enum_to_string(opcode));
 875
 876    switch (opcode) {
 877       case GL_CLEAR:
 878       case GL_SET:
 879       case GL_COPY:
 880       case GL_COPY_INVERTED:
 881       case GL_NOOP:
 882       case GL_INVERT:
 883       case GL_AND:
 884       case GL_NAND:
 885       case GL_OR:
 886       case GL_NOR:
 887       case GL_XOR:
 888       case GL_EQUIV:
 889       case GL_AND_REVERSE:
 890       case GL_AND_INVERTED:
 891       case GL_OR_REVERSE:
 892       case GL_OR_INVERTED:
 893          break;
 894       default:
 895          _mesa_error( ctx, GL_INVALID_ENUM, "glLogicOp" );
 896          return;
 897    }
 898
 899    logic_op(ctx, opcode);
 900 }
 901
 902
 903 void GLAPIENTRY
 904 _mesa_LogicOp_no_error(GLenum opcode)
 905 {
 906    GET_CURRENT_CONTEXT(ctx);
 907    logic_op(ctx, opcode);
 908 }
 909
 910
 911 void GLAPIENTRY
 912 _mesa_IndexMask( GLuint mask )
 913 {
 914    GET_CURRENT_CONTEXT(ctx);
 915
 916    if (ctx->Color.IndexMask == mask)
 917       return;
 918
 919    FLUSH_VERTICES(ctx, ctx->DriverFlags.NewColorMask ? 0 : _NEW_COLOR);
 920    ctx->NewDriverState |= ctx->DriverFlags.NewColorMask;
 921    ctx->Color.IndexMask = mask;
 922 }
 923
 924
 925 /**
 926  * Enable or disable writing of frame buffer color components.
 927  *
 928  * \param red whether to mask writing of the red color component.
 929  * \param green whether to mask writing of the green color component.
 930  * \param blue whether to mask writing of the blue color component.
 931  * \param alpha whether to mask writing of the alpha color component.
 932  *
 933  * \sa glColorMask().
 934  *
 935  * Sets the appropriate value of gl_colorbuffer_attrib::ColorMask.  On a
 936  * change, flushes the vertices and notifies the driver via the
 937  * dd_function_table::ColorMask callback.
 938  */
 939 void GLAPIENTRY
 940 _mesa_ColorMask( GLboolean red, GLboolean green,
 941                  GLboolean blue, GLboolean alpha )
 942 {
 943    GET_CURRENT_CONTEXT(ctx);
 944    GLubyte tmp[4];
 945    GLuint i;
 946    GLboolean flushed;
 947
 948    if (MESA_VERBOSE & VERBOSE_API)
 949       _mesa_debug(ctx, "glColorMask(%d, %d, %d, %d)\n",
 950                   red, green, blue, alpha);
 951
 952    /* Shouldn't have any information about channel depth in core mesa
 953     * -- should probably store these as the native booleans:
 954     */
 955    tmp[RCOMP] = red    ? 0xff : 0x0;
 956    tmp[GCOMP] = green  ? 0xff : 0x0;
 957    tmp[BCOMP] = blue   ? 0xff : 0x0;
 958    tmp[ACOMP] = alpha  ? 0xff : 0x0;
 959
 960    flushed = GL_FALSE;
 961    for (i = 0; i < ctx->Const.MaxDrawBuffers; i++) {
 962       if (!TEST_EQ_4V(tmp, ctx->Color.ColorMask[i])) {
 963          if (!flushed) {
 964             FLUSH_VERTICES(ctx, ctx->DriverFlags.NewColorMask ? 0 : _NEW_COLOR);
 965             ctx->NewDriverState |= ctx->DriverFlags.NewColorMask;
 966          }
 967          flushed = GL_TRUE;
 968          COPY_4UBV(ctx->Color.ColorMask[i], tmp);
 969       }
 970    }
 971
 972    if (ctx->Driver.ColorMask)
 973       ctx->Driver.ColorMask( ctx, red, green, blue, alpha );
 974 }
 975
 976
 977 /**
 978  * For GL_EXT_draw_buffers2 and GL3
 979  */
 980 void GLAPIENTRY
 981 _mesa_ColorMaski( GLuint buf, GLboolean red, GLboolean green,
 982                         GLboolean blue, GLboolean alpha )
 983 {
 984    GLubyte tmp[4];
 985    GET_CURRENT_CONTEXT(ctx);
 986
 987    if (MESA_VERBOSE & VERBOSE_API)
 988       _mesa_debug(ctx, "glColorMaskIndexed %u %d %d %d %d\n",
 989                   buf, red, green, blue, alpha);
 990
 991    if (buf >= ctx->Const.MaxDrawBuffers) {
 992       _mesa_error(ctx, GL_INVALID_VALUE, "glColorMaskIndexed(buf=%u)", buf);
 993       return;
 994    }
 995
 996    /* Shouldn't have any information about channel depth in core mesa
 997     * -- should probably store these as the native booleans:
 998     */
 999    tmp[RCOMP] = red    ? 0xff : 0x0;
1000    tmp[GCOMP] = green  ? 0xff : 0x0;
1001    tmp[BCOMP] = blue   ? 0xff : 0x0;
1002    tmp[ACOMP] = alpha  ? 0xff : 0x0;
1003
1004    if (TEST_EQ_4V(tmp, ctx->Color.ColorMask[buf]))
1005       return;
1006
1007    FLUSH_VERTICES(ctx, ctx->DriverFlags.NewColorMask ? 0 : _NEW_COLOR);
1008    ctx->NewDriverState |= ctx->DriverFlags.NewColorMask;
1009    COPY_4UBV(ctx->Color.ColorMask[buf], tmp);
1010 }
1011
1012
1013 void GLAPIENTRY
1014 _mesa_ClampColor(GLenum target, GLenum clamp)
1015 {
1016    GET_CURRENT_CONTEXT(ctx);
1017
1018    /* Check for both the extension and the GL version, since the Intel driver
1019     * does not advertise the extension in core profiles.
1020     */
1021    if (ctx->Version <= 30 && !ctx->Extensions.ARB_color_buffer_float) {
1022       _mesa_error(ctx, GL_INVALID_OPERATION, "glClampColor()");
1023       return;
1024    }
1025
1026    if (clamp != GL_TRUE && clamp != GL_FALSE && clamp != GL_FIXED_ONLY_ARB) {
1027       _mesa_error(ctx, GL_INVALID_ENUM, "glClampColorARB(clamp)");
1028       return;
1029    }
1030
1031    switch (target) {
1032    case GL_CLAMP_VERTEX_COLOR_ARB:
1033       if (ctx->API == API_OPENGL_CORE)
1034          goto invalid_enum;
1035       FLUSH_VERTICES(ctx, _NEW_LIGHT);
1036       ctx->Light.ClampVertexColor = clamp;
1037       _mesa_update_clamp_vertex_color(ctx, ctx->DrawBuffer);
1038       break;
1039    case GL_CLAMP_FRAGMENT_COLOR_ARB:
1040       if (ctx->API == API_OPENGL_CORE)
1041          goto invalid_enum;
1042       FLUSH_VERTICES(ctx, _NEW_FRAG_CLAMP);
1043       ctx->Color.ClampFragmentColor = clamp;
1044       _mesa_update_clamp_fragment_color(ctx, ctx->DrawBuffer);
1045       break;
1046    case GL_CLAMP_READ_COLOR_ARB:
1047       ctx->Color.ClampReadColor = clamp;
1048       break;
1049    default:
1050       goto invalid_enum;
1051    }
1052    return;
1053
1054 invalid_enum:
1055    _mesa_error(ctx, GL_INVALID_ENUM, "glClampColor(%s)",
1056                _mesa_enum_to_string(target));
1057 }
1058
1059 static GLboolean
1060 get_clamp_color(const struct gl_framebuffer *fb, GLenum clamp)
1061 {
1062    if (clamp == GL_TRUE || clamp == GL_FALSE)
1063       return clamp;
1064
1065    assert(clamp == GL_FIXED_ONLY);
1066    if (!fb)
1067       return GL_TRUE;
1068
1069    return fb->_AllColorBuffersFixedPoint;
1070 }
1071
1072 GLboolean
1073 _mesa_get_clamp_fragment_color(const struct gl_context *ctx,
1074                                const struct gl_framebuffer *drawFb)
1075 {
1076    return get_clamp_color(drawFb, ctx->Color.ClampFragmentColor);
1077 }
1078
1079 GLboolean
1080 _mesa_get_clamp_vertex_color(const struct gl_context *ctx,
1081                              const struct gl_framebuffer *drawFb)
1082 {
1083    return get_clamp_color(drawFb, ctx->Light.ClampVertexColor);
1084 }
1085
1086 GLboolean
1087 _mesa_get_clamp_read_color(const struct gl_context *ctx,
1088                            const struct gl_framebuffer *readFb)
1089 {
1090    return get_clamp_color(readFb, ctx->Color.ClampReadColor);
1091 }
1092
1093 /**
1094  * Update the ctx->Color._ClampFragmentColor field
1095  */
1096 void
1097 _mesa_update_clamp_fragment_color(struct gl_context *ctx,
1098                                   const struct gl_framebuffer *drawFb)
1099 {
1100    /* Don't clamp if:
1101     * - there is no colorbuffer
1102     * - all colorbuffers are unsigned normalized, so clamping has no effect
1103     * - there is an integer colorbuffer
1104     */
1105    if (!drawFb || !drawFb->_HasSNormOrFloatColorBuffer ||
1106        drawFb->_IntegerBuffers)
1107       ctx->Color._ClampFragmentColor = GL_FALSE;
1108    else
1109       ctx->Color._ClampFragmentColor =
1110          _mesa_get_clamp_fragment_color(ctx, drawFb);
1111 }
1112
1113 /**
1114  * Update the ctx->Color._ClampVertexColor field
1115  */
1116 void
1117 _mesa_update_clamp_vertex_color(struct gl_context *ctx,
1118                                 const struct gl_framebuffer *drawFb)
1119 {
1120    ctx->Light._ClampVertexColor =
1121          _mesa_get_clamp_vertex_color(ctx, drawFb);
1122 }
1123
1124 /**
1125  * Returns an appropriate mesa_format for color rendering based on the
1126  * GL_FRAMEBUFFER_SRGB state.
1127  *
1128  * Some drivers implement GL_FRAMEBUFFER_SRGB using a flag on the blend state
1129  * (which GL_FRAMEBUFFER_SRGB maps to reasonably), but some have to do so by
1130  * overriding the format of the surface.  This is a helper for doing the
1131  * surface format override variant.
1132  */
1133 mesa_format
1134 _mesa_get_render_format(const struct gl_context *ctx, mesa_format format)
1135 {
1136    if (ctx->Color.sRGBEnabled)
1137       return format;
1138    else
1139       return _mesa_get_srgb_format_linear(format);
1140 }
1141
1142 /**********************************************************************/
1143 /** \name Initialization */
1144 /*@{*/
1145
1146 /**
1147  * Initialization of the context's Color attribute group.
1148  *
1149  * \param ctx GL context.
1150  *
1151  * Initializes the related fields in the context color attribute group,
1152  * __struct gl_contextRec::Color.
1153  */
1154 void _mesa_init_color( struct gl_context * ctx )
1155 {
1156    GLuint i;
1157
1158    /* Color buffer group */
1159    ctx->Color.IndexMask = ~0u;
1160    memset(ctx->Color.ColorMask, 0xff, sizeof(ctx->Color.ColorMask));
1161    ctx->Color.ClearIndex = 0;
1162    ASSIGN_4V( ctx->Color.ClearColor.f, 0, 0, 0, 0 );
1163    ctx->Color.AlphaEnabled = GL_FALSE;
1164    ctx->Color.AlphaFunc = GL_ALWAYS;
1165    ctx->Color.AlphaRef = 0;
1166    ctx->Color.BlendEnabled = 0x0;
1167    for (i = 0; i < ARRAY_SIZE(ctx->Color.Blend); i++) {
1168       ctx->Color.Blend[i].SrcRGB = GL_ONE;
1169       ctx->Color.Blend[i].DstRGB = GL_ZERO;
1170       ctx->Color.Blend[i].SrcA = GL_ONE;
1171       ctx->Color.Blend[i].DstA = GL_ZERO;
1172       ctx->Color.Blend[i].EquationRGB = GL_FUNC_ADD;
1173       ctx->Color.Blend[i].EquationA = GL_FUNC_ADD;
1174    }
1175    ASSIGN_4V( ctx->Color.BlendColor, 0.0, 0.0, 0.0, 0.0 );
1176    ASSIGN_4V( ctx->Color.BlendColorUnclamped, 0.0, 0.0, 0.0, 0.0 );
1177    ctx->Color.IndexLogicOpEnabled = GL_FALSE;
1178    ctx->Color.ColorLogicOpEnabled = GL_FALSE;
1179    ctx->Color.LogicOp = GL_COPY;
1180    ctx->Color.DitherFlag = GL_TRUE;
1181
1182    /* GL_FRONT is not possible on GLES. Instead GL_BACK will render to either
1183     * the front or the back buffer depending on the config */
1184    if (ctx->Visual.doubleBufferMode || _mesa_is_gles(ctx)) {
1185       ctx->Color.DrawBuffer[0] = GL_BACK;
1186    }
1187    else {
1188       ctx->Color.DrawBuffer[0] = GL_FRONT;
1189    }
1190
1191    ctx->Color.ClampFragmentColor = ctx->API == API_OPENGL_COMPAT ?
1192                                    GL_FIXED_ONLY_ARB : GL_FALSE;
1193    ctx->Color._ClampFragmentColor = GL_FALSE;
1194    ctx->Color.ClampReadColor = GL_FIXED_ONLY_ARB;
1195
1196    /* GLES 1/2/3 behaves as though GL_FRAMEBUFFER_SRGB is always enabled
1197     * if EGL_KHR_gl_colorspace has been used to request sRGB.
1198     */
1199    ctx->Color.sRGBEnabled = _mesa_is_gles(ctx);
1200
1201    ctx->Color.BlendCoherent = true;
1202 }
1203
1204 /*@}*/