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_no_error(GLenum modeRGB, GLenum modeA)
 677 {
 678    GET_CURRENT_CONTEXT(ctx);
 679    blend_equation_separate(ctx, modeRGB, modeA, true);
 680 }
 681
 682
 683 void GLAPIENTRY
 684 _mesa_BlendEquationSeparate(GLenum modeRGB, GLenum modeA)
 685 {
 686    GET_CURRENT_CONTEXT(ctx);
 687
 688    if (MESA_VERBOSE & VERBOSE_API)
 689       _mesa_debug(ctx, "glBlendEquationSeparateEXT(%s %s)\n",
 690                   _mesa_enum_to_string(modeRGB),
 691                   _mesa_enum_to_string(modeA));
 692
 693    blend_equation_separate(ctx, modeRGB, modeA, false);
 694 }
 695
 696
 697 static void
 698 blend_equation_separatei(struct gl_context *ctx, GLuint buf, GLenum modeRGB,
 699                          GLenum modeA)
 700 {
 701    if (ctx->Color.Blend[buf].EquationRGB == modeRGB &&
 702        ctx->Color.Blend[buf].EquationA == modeA)
 703       return;  /* no change */
 704
 705    _mesa_flush_vertices_for_blend_state(ctx);
 706    ctx->Color.Blend[buf].EquationRGB = modeRGB;
 707    ctx->Color.Blend[buf].EquationA = modeA;
 708    ctx->Color._BlendEquationPerBuffer = GL_TRUE;
 709    ctx->Color._AdvancedBlendMode = BLEND_NONE;
 710 }
 711
 712
 713 void GLAPIENTRY
 714 _mesa_BlendEquationSeparateiARB_no_error(GLuint buf, GLenum modeRGB,
 715                                          GLenum modeA)
 716 {
 717    GET_CURRENT_CONTEXT(ctx);
 718    blend_equation_separatei(ctx, buf, modeRGB, modeA);
 719 }
 720
 721
 722 /**
 723  * Set separate blend equations for one color buffer/target.
 724  */
 725 void GLAPIENTRY
 726 _mesa_BlendEquationSeparateiARB(GLuint buf, GLenum modeRGB, GLenum modeA)
 727 {
 728    GET_CURRENT_CONTEXT(ctx);
 729
 730    if (MESA_VERBOSE & VERBOSE_API)
 731       _mesa_debug(ctx, "glBlendEquationSeparatei(%u, %s %s)\n", buf,
 732                   _mesa_enum_to_string(modeRGB),
 733                   _mesa_enum_to_string(modeA));
 734
 735    if (buf >= ctx->Const.MaxDrawBuffers) {
 736       _mesa_error(ctx, GL_INVALID_VALUE, "glBlendEquationSeparatei(buffer=%u)",
 737                   buf);
 738       return;
 739    }
 740
 741    /* Only allow simple blending equations.
 742     * The GL_KHR_blend_equation_advanced spec says:
 743     *
 744     *    "NOTE: These enums are not accepted by the <modeRGB> or <modeAlpha>
 745     *     parameters of BlendEquationSeparate or BlendEquationSeparatei."
 746     */
 747    if (!legal_simple_blend_equation(ctx, modeRGB)) {
 748       _mesa_error(ctx, GL_INVALID_ENUM, "glBlendEquationSeparatei(modeRGB)");
 749       return;
 750    }
 751
 752    if (!legal_simple_blend_equation(ctx, modeA)) {
 753       _mesa_error(ctx, GL_INVALID_ENUM, "glBlendEquationSeparatei(modeA)");
 754       return;
 755    }
 756
 757    blend_equation_separatei(ctx, buf, modeRGB, modeA);
 758 }
 759
 760
 761 /**
 762  * Set the blending color.
 763  *
 764  * \param red red color component.
 765  * \param green green color component.
 766  * \param blue blue color component.
 767  * \param alpha alpha color component.
 768  *
 769  * \sa glBlendColor().
 770  *
 771  * Clamps the parameters and updates gl_colorbuffer_attrib::BlendColor.  On a
 772  * change, flushes the vertices and notifies the driver via
 773  * dd_function_table::BlendColor callback.
 774  */
 775 void GLAPIENTRY
 776 _mesa_BlendColor( GLclampf red, GLclampf green, GLclampf blue, GLclampf alpha )
 777 {
 778    GLfloat tmp[4];
 779    GET_CURRENT_CONTEXT(ctx);
 780
 781    tmp[0] = red;
 782    tmp[1] = green;
 783    tmp[2] = blue;
 784    tmp[3] = alpha;
 785
 786    if (TEST_EQ_4V(tmp, ctx->Color.BlendColorUnclamped))
 787       return;
 788
 789    FLUSH_VERTICES(ctx, ctx->DriverFlags.NewBlendColor ? 0 : _NEW_COLOR);
 790    ctx->NewDriverState |= ctx->DriverFlags.NewBlendColor;
 791    COPY_4FV( ctx->Color.BlendColorUnclamped, tmp );
 792
 793    ctx->Color.BlendColor[0] = CLAMP(tmp[0], 0.0F, 1.0F);
 794    ctx->Color.BlendColor[1] = CLAMP(tmp[1], 0.0F, 1.0F);
 795    ctx->Color.BlendColor[2] = CLAMP(tmp[2], 0.0F, 1.0F);
 796    ctx->Color.BlendColor[3] = CLAMP(tmp[3], 0.0F, 1.0F);
 797
 798    if (ctx->Driver.BlendColor)
 799       ctx->Driver.BlendColor(ctx, ctx->Color.BlendColor);
 800 }
 801
 802
 803 /**
 804  * Specify the alpha test function.
 805  *
 806  * \param func alpha comparison function.
 807  * \param ref reference value.
 808  *
 809  * Verifies the parameters and updates gl_colorbuffer_attrib.
 810  * On a change, flushes the vertices and notifies the driver via
 811  * dd_function_table::AlphaFunc callback.
 812  */
 813 void GLAPIENTRY
 814 _mesa_AlphaFunc( GLenum func, GLclampf ref )
 815 {
 816    GET_CURRENT_CONTEXT(ctx);
 817
 818    if (MESA_VERBOSE & VERBOSE_API)
 819       _mesa_debug(ctx, "glAlphaFunc(%s, %f)\n",
 820                   _mesa_enum_to_string(func), ref);
 821
 822    if (ctx->Color.AlphaFunc == func && ctx->Color.AlphaRefUnclamped == ref)
 823       return; /* no change */
 824
 825    switch (func) {
 826    case GL_NEVER:
 827    case GL_LESS:
 828    case GL_EQUAL:
 829    case GL_LEQUAL:
 830    case GL_GREATER:
 831    case GL_NOTEQUAL:
 832    case GL_GEQUAL:
 833    case GL_ALWAYS:
 834       FLUSH_VERTICES(ctx, ctx->DriverFlags.NewAlphaTest ? 0 : _NEW_COLOR);
 835       ctx->NewDriverState |= ctx->DriverFlags.NewAlphaTest;
 836       ctx->Color.AlphaFunc = func;
 837       ctx->Color.AlphaRefUnclamped = ref;
 838       ctx->Color.AlphaRef = CLAMP(ref, 0.0F, 1.0F);
 839
 840       if (ctx->Driver.AlphaFunc)
 841          ctx->Driver.AlphaFunc(ctx, func, ctx->Color.AlphaRef);
 842       return;
 843
 844    default:
 845       _mesa_error( ctx, GL_INVALID_ENUM, "glAlphaFunc(func)" );
 846       return;
 847    }
 848 }
 849
 850
 851 static void
 852 logic_op(struct gl_context *ctx, GLenum opcode)
 853 {
 854    if (ctx->Color.LogicOp == opcode)
 855       return;
 856
 857    FLUSH_VERTICES(ctx, ctx->DriverFlags.NewLogicOp ? 0 : _NEW_COLOR);
 858    ctx->NewDriverState |= ctx->DriverFlags.NewLogicOp;
 859    ctx->Color.LogicOp = opcode;
 860
 861    if (ctx->Driver.LogicOpcode)
 862       ctx->Driver.LogicOpcode(ctx, opcode);
 863 }
 864
 865
 866 /**
 867  * Specify a logic pixel operation for color index rendering.
 868  *
 869  * \param opcode operation.
 870  *
 871  * Verifies that \p opcode is a valid enum and updates
 872  * gl_colorbuffer_attrib::LogicOp.
 873  * On a change, flushes the vertices and notifies the driver via the
 874  * dd_function_table::LogicOpcode callback.
 875  */
 876 void GLAPIENTRY
 877 _mesa_LogicOp( GLenum opcode )
 878 {
 879    GET_CURRENT_CONTEXT(ctx);
 880
 881    if (MESA_VERBOSE & VERBOSE_API)
 882       _mesa_debug(ctx, "glLogicOp(%s)\n", _mesa_enum_to_string(opcode));
 883
 884    switch (opcode) {
 885       case GL_CLEAR:
 886       case GL_SET:
 887       case GL_COPY:
 888       case GL_COPY_INVERTED:
 889       case GL_NOOP:
 890       case GL_INVERT:
 891       case GL_AND:
 892       case GL_NAND:
 893       case GL_OR:
 894       case GL_NOR:
 895       case GL_XOR:
 896       case GL_EQUIV:
 897       case GL_AND_REVERSE:
 898       case GL_AND_INVERTED:
 899       case GL_OR_REVERSE:
 900       case GL_OR_INVERTED:
 901          break;
 902       default:
 903          _mesa_error( ctx, GL_INVALID_ENUM, "glLogicOp" );
 904          return;
 905    }
 906
 907    logic_op(ctx, opcode);
 908 }
 909
 910
 911 void GLAPIENTRY
 912 _mesa_LogicOp_no_error(GLenum opcode)
 913 {
 914    GET_CURRENT_CONTEXT(ctx);
 915    logic_op(ctx, opcode);
 916 }
 917
 918
 919 void GLAPIENTRY
 920 _mesa_IndexMask( GLuint mask )
 921 {
 922    GET_CURRENT_CONTEXT(ctx);
 923
 924    if (ctx->Color.IndexMask == mask)
 925       return;
 926
 927    FLUSH_VERTICES(ctx, ctx->DriverFlags.NewColorMask ? 0 : _NEW_COLOR);
 928    ctx->NewDriverState |= ctx->DriverFlags.NewColorMask;
 929    ctx->Color.IndexMask = mask;
 930 }
 931
 932
 933 /**
 934  * Enable or disable writing of frame buffer color components.
 935  *
 936  * \param red whether to mask writing of the red color component.
 937  * \param green whether to mask writing of the green color component.
 938  * \param blue whether to mask writing of the blue color component.
 939  * \param alpha whether to mask writing of the alpha color component.
 940  *
 941  * \sa glColorMask().
 942  *
 943  * Sets the appropriate value of gl_colorbuffer_attrib::ColorMask.  On a
 944  * change, flushes the vertices and notifies the driver via the
 945  * dd_function_table::ColorMask callback.
 946  */
 947 void GLAPIENTRY
 948 _mesa_ColorMask( GLboolean red, GLboolean green,
 949                  GLboolean blue, GLboolean alpha )
 950 {
 951    GET_CURRENT_CONTEXT(ctx);
 952    GLubyte tmp[4];
 953    GLuint i;
 954    GLboolean flushed;
 955
 956    if (MESA_VERBOSE & VERBOSE_API)
 957       _mesa_debug(ctx, "glColorMask(%d, %d, %d, %d)\n",
 958                   red, green, blue, alpha);
 959
 960    /* Shouldn't have any information about channel depth in core mesa
 961     * -- should probably store these as the native booleans:
 962     */
 963    tmp[RCOMP] = red    ? 0xff : 0x0;
 964    tmp[GCOMP] = green  ? 0xff : 0x0;
 965    tmp[BCOMP] = blue   ? 0xff : 0x0;
 966    tmp[ACOMP] = alpha  ? 0xff : 0x0;
 967
 968    flushed = GL_FALSE;
 969    for (i = 0; i < ctx->Const.MaxDrawBuffers; i++) {
 970       if (!TEST_EQ_4V(tmp, ctx->Color.ColorMask[i])) {
 971          if (!flushed) {
 972             FLUSH_VERTICES(ctx, ctx->DriverFlags.NewColorMask ? 0 : _NEW_COLOR);
 973             ctx->NewDriverState |= ctx->DriverFlags.NewColorMask;
 974          }
 975          flushed = GL_TRUE;
 976          COPY_4UBV(ctx->Color.ColorMask[i], tmp);
 977       }
 978    }
 979
 980    if (ctx->Driver.ColorMask)
 981       ctx->Driver.ColorMask( ctx, red, green, blue, alpha );
 982 }
 983
 984
 985 /**
 986  * For GL_EXT_draw_buffers2 and GL3
 987  */
 988 void GLAPIENTRY
 989 _mesa_ColorMaski( GLuint buf, GLboolean red, GLboolean green,
 990                         GLboolean blue, GLboolean alpha )
 991 {
 992    GLubyte tmp[4];
 993    GET_CURRENT_CONTEXT(ctx);
 994
 995    if (MESA_VERBOSE & VERBOSE_API)
 996       _mesa_debug(ctx, "glColorMaskIndexed %u %d %d %d %d\n",
 997                   buf, red, green, blue, alpha);
 998
 999    if (buf >= ctx->Const.MaxDrawBuffers) {
1000       _mesa_error(ctx, GL_INVALID_VALUE, "glColorMaskIndexed(buf=%u)", buf);
1001       return;
1002    }
1003
1004    /* Shouldn't have any information about channel depth in core mesa
1005     * -- should probably store these as the native booleans:
1006     */
1007    tmp[RCOMP] = red    ? 0xff : 0x0;
1008    tmp[GCOMP] = green  ? 0xff : 0x0;
1009    tmp[BCOMP] = blue   ? 0xff : 0x0;
1010    tmp[ACOMP] = alpha  ? 0xff : 0x0;
1011
1012    if (TEST_EQ_4V(tmp, ctx->Color.ColorMask[buf]))
1013       return;
1014
1015    FLUSH_VERTICES(ctx, ctx->DriverFlags.NewColorMask ? 0 : _NEW_COLOR);
1016    ctx->NewDriverState |= ctx->DriverFlags.NewColorMask;
1017    COPY_4UBV(ctx->Color.ColorMask[buf], tmp);
1018 }
1019
1020
1021 void GLAPIENTRY
1022 _mesa_ClampColor(GLenum target, GLenum clamp)
1023 {
1024    GET_CURRENT_CONTEXT(ctx);
1025
1026    /* Check for both the extension and the GL version, since the Intel driver
1027     * does not advertise the extension in core profiles.
1028     */
1029    if (ctx->Version <= 30 && !ctx->Extensions.ARB_color_buffer_float) {
1030       _mesa_error(ctx, GL_INVALID_OPERATION, "glClampColor()");
1031       return;
1032    }
1033
1034    if (clamp != GL_TRUE && clamp != GL_FALSE && clamp != GL_FIXED_ONLY_ARB) {
1035       _mesa_error(ctx, GL_INVALID_ENUM, "glClampColorARB(clamp)");
1036       return;
1037    }
1038
1039    switch (target) {
1040    case GL_CLAMP_VERTEX_COLOR_ARB:
1041       if (ctx->API == API_OPENGL_CORE)
1042          goto invalid_enum;
1043       FLUSH_VERTICES(ctx, _NEW_LIGHT);
1044       ctx->Light.ClampVertexColor = clamp;
1045       _mesa_update_clamp_vertex_color(ctx, ctx->DrawBuffer);
1046       break;
1047    case GL_CLAMP_FRAGMENT_COLOR_ARB:
1048       if (ctx->API == API_OPENGL_CORE)
1049          goto invalid_enum;
1050       FLUSH_VERTICES(ctx, _NEW_FRAG_CLAMP);
1051       ctx->Color.ClampFragmentColor = clamp;
1052       _mesa_update_clamp_fragment_color(ctx, ctx->DrawBuffer);
1053       break;
1054    case GL_CLAMP_READ_COLOR_ARB:
1055       ctx->Color.ClampReadColor = clamp;
1056       break;
1057    default:
1058       goto invalid_enum;
1059    }
1060    return;
1061
1062 invalid_enum:
1063    _mesa_error(ctx, GL_INVALID_ENUM, "glClampColor(%s)",
1064                _mesa_enum_to_string(target));
1065 }
1066
1067 static GLboolean
1068 get_clamp_color(const struct gl_framebuffer *fb, GLenum clamp)
1069 {
1070    if (clamp == GL_TRUE || clamp == GL_FALSE)
1071       return clamp;
1072
1073    assert(clamp == GL_FIXED_ONLY);
1074    if (!fb)
1075       return GL_TRUE;
1076
1077    return fb->_AllColorBuffersFixedPoint;
1078 }
1079
1080 GLboolean
1081 _mesa_get_clamp_fragment_color(const struct gl_context *ctx,
1082                                const struct gl_framebuffer *drawFb)
1083 {
1084    return get_clamp_color(drawFb, ctx->Color.ClampFragmentColor);
1085 }
1086
1087 GLboolean
1088 _mesa_get_clamp_vertex_color(const struct gl_context *ctx,
1089                              const struct gl_framebuffer *drawFb)
1090 {
1091    return get_clamp_color(drawFb, ctx->Light.ClampVertexColor);
1092 }
1093
1094 GLboolean
1095 _mesa_get_clamp_read_color(const struct gl_context *ctx,
1096                            const struct gl_framebuffer *readFb)
1097 {
1098    return get_clamp_color(readFb, ctx->Color.ClampReadColor);
1099 }
1100
1101 /**
1102  * Update the ctx->Color._ClampFragmentColor field
1103  */
1104 void
1105 _mesa_update_clamp_fragment_color(struct gl_context *ctx,
1106                                   const struct gl_framebuffer *drawFb)
1107 {
1108    /* Don't clamp if:
1109     * - there is no colorbuffer
1110     * - all colorbuffers are unsigned normalized, so clamping has no effect
1111     * - there is an integer colorbuffer
1112     */
1113    if (!drawFb || !drawFb->_HasSNormOrFloatColorBuffer ||
1114        drawFb->_IntegerBuffers)
1115       ctx->Color._ClampFragmentColor = GL_FALSE;
1116    else
1117       ctx->Color._ClampFragmentColor =
1118          _mesa_get_clamp_fragment_color(ctx, drawFb);
1119 }
1120
1121 /**
1122  * Update the ctx->Color._ClampVertexColor field
1123  */
1124 void
1125 _mesa_update_clamp_vertex_color(struct gl_context *ctx,
1126                                 const struct gl_framebuffer *drawFb)
1127 {
1128    ctx->Light._ClampVertexColor =
1129          _mesa_get_clamp_vertex_color(ctx, drawFb);
1130 }
1131
1132 /**
1133  * Returns an appropriate mesa_format for color rendering based on the
1134  * GL_FRAMEBUFFER_SRGB state.
1135  *
1136  * Some drivers implement GL_FRAMEBUFFER_SRGB using a flag on the blend state
1137  * (which GL_FRAMEBUFFER_SRGB maps to reasonably), but some have to do so by
1138  * overriding the format of the surface.  This is a helper for doing the
1139  * surface format override variant.
1140  */
1141 mesa_format
1142 _mesa_get_render_format(const struct gl_context *ctx, mesa_format format)
1143 {
1144    if (ctx->Color.sRGBEnabled)
1145       return format;
1146    else
1147       return _mesa_get_srgb_format_linear(format);
1148 }
1149
1150 /**********************************************************************/
1151 /** \name Initialization */
1152 /*@{*/
1153
1154 /**
1155  * Initialization of the context's Color attribute group.
1156  *
1157  * \param ctx GL context.
1158  *
1159  * Initializes the related fields in the context color attribute group,
1160  * __struct gl_contextRec::Color.
1161  */
1162 void _mesa_init_color( struct gl_context * ctx )
1163 {
1164    GLuint i;
1165
1166    /* Color buffer group */
1167    ctx->Color.IndexMask = ~0u;
1168    memset(ctx->Color.ColorMask, 0xff, sizeof(ctx->Color.ColorMask));
1169    ctx->Color.ClearIndex = 0;
1170    ASSIGN_4V( ctx->Color.ClearColor.f, 0, 0, 0, 0 );
1171    ctx->Color.AlphaEnabled = GL_FALSE;
1172    ctx->Color.AlphaFunc = GL_ALWAYS;
1173    ctx->Color.AlphaRef = 0;
1174    ctx->Color.BlendEnabled = 0x0;
1175    for (i = 0; i < ARRAY_SIZE(ctx->Color.Blend); i++) {
1176       ctx->Color.Blend[i].SrcRGB = GL_ONE;
1177       ctx->Color.Blend[i].DstRGB = GL_ZERO;
1178       ctx->Color.Blend[i].SrcA = GL_ONE;
1179       ctx->Color.Blend[i].DstA = GL_ZERO;
1180       ctx->Color.Blend[i].EquationRGB = GL_FUNC_ADD;
1181       ctx->Color.Blend[i].EquationA = GL_FUNC_ADD;
1182    }
1183    ASSIGN_4V( ctx->Color.BlendColor, 0.0, 0.0, 0.0, 0.0 );
1184    ASSIGN_4V( ctx->Color.BlendColorUnclamped, 0.0, 0.0, 0.0, 0.0 );
1185    ctx->Color.IndexLogicOpEnabled = GL_FALSE;
1186    ctx->Color.ColorLogicOpEnabled = GL_FALSE;
1187    ctx->Color.LogicOp = GL_COPY;
1188    ctx->Color.DitherFlag = GL_TRUE;
1189
1190    /* GL_FRONT is not possible on GLES. Instead GL_BACK will render to either
1191     * the front or the back buffer depending on the config */
1192    if (ctx->Visual.doubleBufferMode || _mesa_is_gles(ctx)) {
1193       ctx->Color.DrawBuffer[0] = GL_BACK;
1194    }
1195    else {
1196       ctx->Color.DrawBuffer[0] = GL_FRONT;
1197    }
1198
1199    ctx->Color.ClampFragmentColor = ctx->API == API_OPENGL_COMPAT ?
1200                                    GL_FIXED_ONLY_ARB : GL_FALSE;
1201    ctx->Color._ClampFragmentColor = GL_FALSE;
1202    ctx->Color.ClampReadColor = GL_FIXED_ONLY_ARB;
1203
1204    /* GLES 1/2/3 behaves as though GL_FRAMEBUFFER_SRGB is always enabled
1205     * if EGL_KHR_gl_colorspace has been used to request sRGB.
1206     */
1207    ctx->Color.sRGBEnabled = _mesa_is_gles(ctx);
1208
1209    ctx->Color.BlendCoherent = true;
1210 }
1211
1212 /*@}*/