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 _mesa_is_desktop_gl(ctx)
  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 (_mesa_is_desktop_gl(ctx)
 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 _mesa_is_desktop_gl(ctx)
 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 /**
 161  * Specify the blending operation.
 162  *
 163  * \param sfactor source factor operator.
 164  * \param dfactor destination factor operator.
 165  *
 166  * \sa glBlendFunc, glBlendFuncSeparateEXT
 167  */
 168 void GLAPIENTRY
 169 _mesa_BlendFunc( GLenum sfactor, GLenum dfactor )
 170 {
 171    _mesa_BlendFuncSeparate(sfactor, dfactor, sfactor, dfactor);
 172 }
 173
 174 static GLboolean
 175 blend_factor_is_dual_src(GLenum factor)
 176 {
 177    return (factor == GL_SRC1_COLOR ||
 178            factor == GL_SRC1_ALPHA ||
 179            factor == GL_ONE_MINUS_SRC1_COLOR ||
 180            factor == GL_ONE_MINUS_SRC1_ALPHA);
 181 }
 182
 183 static void
 184 update_uses_dual_src(struct gl_context *ctx, int buf)
 185 {
 186    ctx->Color.Blend[buf]._UsesDualSrc =
 187       (blend_factor_is_dual_src(ctx->Color.Blend[buf].SrcRGB) ||
 188        blend_factor_is_dual_src(ctx->Color.Blend[buf].DstRGB) ||
 189        blend_factor_is_dual_src(ctx->Color.Blend[buf].SrcA) ||
 190        blend_factor_is_dual_src(ctx->Color.Blend[buf].DstA));
 191 }
 192
 193 /**
 194  * Set the separate blend source/dest factors for all draw buffers.
 195  *
 196  * \param sfactorRGB RGB source factor operator.
 197  * \param dfactorRGB RGB destination factor operator.
 198  * \param sfactorA alpha source factor operator.
 199  * \param dfactorA alpha destination factor operator.
 200  */
 201 void GLAPIENTRY
 202 _mesa_BlendFuncSeparate( GLenum sfactorRGB, GLenum dfactorRGB,
 203                             GLenum sfactorA, GLenum dfactorA )
 204 {
 205    GLuint buf, numBuffers;
 206    bool changed = false;
 207    GET_CURRENT_CONTEXT(ctx);
 208
 209    if (MESA_VERBOSE & VERBOSE_API)
 210       _mesa_debug(ctx, "glBlendFuncSeparate %s %s %s %s\n",
 211                   _mesa_enum_to_string(sfactorRGB),
 212                   _mesa_enum_to_string(dfactorRGB),
 213                   _mesa_enum_to_string(sfactorA),
 214                   _mesa_enum_to_string(dfactorA));
 215
 216    numBuffers = ctx->Extensions.ARB_draw_buffers_blend
 217       ? ctx->Const.MaxDrawBuffers : 1;
 218
 219    /* Check if we're really changing any state.  If not, return early. */
 220    if (ctx->Color._BlendFuncPerBuffer) {
 221       /* Check all per-buffer states */
 222       for (buf = 0; buf < numBuffers; buf++) {
 223          if (ctx->Color.Blend[buf].SrcRGB != sfactorRGB ||
 224              ctx->Color.Blend[buf].DstRGB != dfactorRGB ||
 225              ctx->Color.Blend[buf].SrcA != sfactorA ||
 226              ctx->Color.Blend[buf].DstA != dfactorA) {
 227             changed = true;
 228             break;
 229          }
 230       }
 231    }
 232    else {
 233       /* only need to check 0th per-buffer state */
 234       if (ctx->Color.Blend[0].SrcRGB != sfactorRGB ||
 235           ctx->Color.Blend[0].DstRGB != dfactorRGB ||
 236           ctx->Color.Blend[0].SrcA != sfactorA ||
 237           ctx->Color.Blend[0].DstA != dfactorA) {
 238          changed = true;
 239       }
 240    }
 241
 242    if (!changed)
 243       return;
 244
 245    if (!validate_blend_factors(ctx, "glBlendFuncSeparate",
 246                                sfactorRGB, dfactorRGB,
 247                                sfactorA, dfactorA)) {
 248       return;
 249    }
 250
 251    FLUSH_VERTICES(ctx, _NEW_COLOR);
 252
 253    for (buf = 0; buf < numBuffers; buf++) {
 254       ctx->Color.Blend[buf].SrcRGB = sfactorRGB;
 255       ctx->Color.Blend[buf].DstRGB = dfactorRGB;
 256       ctx->Color.Blend[buf].SrcA = sfactorA;
 257       ctx->Color.Blend[buf].DstA = dfactorA;
 258       update_uses_dual_src(ctx, buf);
 259    }
 260    ctx->Color._BlendFuncPerBuffer = GL_FALSE;
 261
 262    if (ctx->Driver.BlendFuncSeparate) {
 263       ctx->Driver.BlendFuncSeparate(ctx, sfactorRGB, dfactorRGB,
 264                                     sfactorA, dfactorA);
 265    }
 266 }
 267
 268
 269 /**
 270  * Set blend source/dest factors for one color buffer/target.
 271  */
 272 void GLAPIENTRY
 273 _mesa_BlendFunciARB(GLuint buf, GLenum sfactor, GLenum dfactor)
 274 {
 275    _mesa_BlendFuncSeparateiARB(buf, sfactor, dfactor, sfactor, dfactor);
 276 }
 277
 278
 279 /**
 280  * Set separate blend source/dest factors for one color buffer/target.
 281  */
 282 void GLAPIENTRY
 283 _mesa_BlendFuncSeparateiARB(GLuint buf, GLenum sfactorRGB, GLenum dfactorRGB,
 284                          GLenum sfactorA, GLenum dfactorA)
 285 {
 286    GET_CURRENT_CONTEXT(ctx);
 287
 288    if (!ctx->Extensions.ARB_draw_buffers_blend) {
 289       _mesa_error(ctx, GL_INVALID_OPERATION, "glBlendFunc[Separate]i()");
 290       return;
 291    }
 292
 293    if (buf >= ctx->Const.MaxDrawBuffers) {
 294       _mesa_error(ctx, GL_INVALID_VALUE, "glBlendFuncSeparatei(buffer=%u)",
 295                   buf);
 296       return;
 297    }
 298
 299    if (!validate_blend_factors(ctx, "glBlendFuncSeparatei",
 300                                sfactorRGB, dfactorRGB,
 301                                sfactorA, dfactorA)) {
 302       return;
 303    }
 304
 305    if (ctx->Color.Blend[buf].SrcRGB == sfactorRGB &&
 306        ctx->Color.Blend[buf].DstRGB == dfactorRGB &&
 307        ctx->Color.Blend[buf].SrcA == sfactorA &&
 308        ctx->Color.Blend[buf].DstA == dfactorA)
 309       return; /* no change */
 310
 311    FLUSH_VERTICES(ctx, _NEW_COLOR);
 312
 313    ctx->Color.Blend[buf].SrcRGB = sfactorRGB;
 314    ctx->Color.Blend[buf].DstRGB = dfactorRGB;
 315    ctx->Color.Blend[buf].SrcA = sfactorA;
 316    ctx->Color.Blend[buf].DstA = dfactorA;
 317    update_uses_dual_src(ctx, buf);
 318    ctx->Color._BlendFuncPerBuffer = GL_TRUE;
 319 }
 320
 321
 322 /**
 323  * Check if given blend equation is legal.
 324  * \return GL_TRUE if legal, GL_FALSE otherwise.
 325  */
 326 static GLboolean
 327 legal_blend_equation(const struct gl_context *ctx, GLenum mode)
 328 {
 329    switch (mode) {
 330    case GL_FUNC_ADD:
 331    case GL_FUNC_SUBTRACT:
 332    case GL_FUNC_REVERSE_SUBTRACT:
 333       return GL_TRUE;
 334    case GL_MIN:
 335    case GL_MAX:
 336       return ctx->Extensions.EXT_blend_minmax;
 337    default:
 338       return GL_FALSE;
 339    }
 340 }
 341
 342
 343 /* This is really an extension function! */
 344 void GLAPIENTRY
 345 _mesa_BlendEquation( GLenum mode )
 346 {
 347    GLuint buf, numBuffers;
 348    bool changed = false;
 349    GET_CURRENT_CONTEXT(ctx);
 350
 351    if (MESA_VERBOSE & VERBOSE_API)
 352       _mesa_debug(ctx, "glBlendEquation(%s)\n",
 353                   _mesa_enum_to_string(mode));
 354
 355    numBuffers = ctx->Extensions.ARB_draw_buffers_blend
 356       ? ctx->Const.MaxDrawBuffers : 1;
 357
 358    if (ctx->Color._BlendEquationPerBuffer) {
 359       /* Check all per-buffer states */
 360       for (buf = 0; buf < numBuffers; buf++) {
 361          if (ctx->Color.Blend[buf].EquationRGB != mode ||
 362              ctx->Color.Blend[buf].EquationA != mode) {
 363             changed = true;
 364             break;
 365          }
 366       }
 367    }
 368    else {
 369       /* only need to check 0th per-buffer state */
 370       if (ctx->Color.Blend[0].EquationRGB != mode ||
 371           ctx->Color.Blend[0].EquationA != mode) {
 372          changed = true;
 373       }
 374    }
 375
 376    if (!changed)
 377       return;
 378
 379    if (!legal_blend_equation(ctx, mode)) {
 380       _mesa_error(ctx, GL_INVALID_ENUM, "glBlendEquation");
 381       return;
 382    }
 383
 384    FLUSH_VERTICES(ctx, _NEW_COLOR);
 385
 386    for (buf = 0; buf < numBuffers; buf++) {
 387       ctx->Color.Blend[buf].EquationRGB = mode;
 388       ctx->Color.Blend[buf].EquationA = mode;
 389    }
 390    ctx->Color._BlendEquationPerBuffer = GL_FALSE;
 391
 392    if (ctx->Driver.BlendEquationSeparate)
 393       (*ctx->Driver.BlendEquationSeparate)( ctx, mode, mode );
 394 }
 395
 396
 397 /**
 398  * Set blend equation for one color buffer/target.
 399  */
 400 void GLAPIENTRY
 401 _mesa_BlendEquationiARB(GLuint buf, GLenum mode)
 402 {
 403    GET_CURRENT_CONTEXT(ctx);
 404
 405    if (MESA_VERBOSE & VERBOSE_API)
 406       _mesa_debug(ctx, "glBlendEquationi(%u, %s)\n",
 407                   buf, _mesa_enum_to_string(mode));
 408
 409    if (buf >= ctx->Const.MaxDrawBuffers) {
 410       _mesa_error(ctx, GL_INVALID_VALUE, "glBlendFuncSeparatei(buffer=%u)",
 411                   buf);
 412       return;
 413    }
 414
 415    if (!legal_blend_equation(ctx, mode)) {
 416       _mesa_error(ctx, GL_INVALID_ENUM, "glBlendEquationi");
 417       return;
 418    }
 419
 420    if (ctx->Color.Blend[buf].EquationRGB == mode &&
 421        ctx->Color.Blend[buf].EquationA == mode)
 422       return;  /* no change */
 423
 424    FLUSH_VERTICES(ctx, _NEW_COLOR);
 425    ctx->Color.Blend[buf].EquationRGB = mode;
 426    ctx->Color.Blend[buf].EquationA = mode;
 427    ctx->Color._BlendEquationPerBuffer = GL_TRUE;
 428 }
 429
 430
 431 void GLAPIENTRY
 432 _mesa_BlendEquationSeparate( GLenum modeRGB, GLenum modeA )
 433 {
 434    GLuint buf, numBuffers;
 435    GLboolean changed;
 436    GET_CURRENT_CONTEXT(ctx);
 437
 438    if (MESA_VERBOSE & VERBOSE_API)
 439       _mesa_debug(ctx, "glBlendEquationSeparateEXT(%s %s)\n",
 440                   _mesa_enum_to_string(modeRGB),
 441                   _mesa_enum_to_string(modeA));
 442
 443    if ( (modeRGB != modeA) && !ctx->Extensions.EXT_blend_equation_separate ) {
 444       _mesa_error(ctx, GL_INVALID_OPERATION,
 445                   "glBlendEquationSeparateEXT not supported by driver");
 446       return;
 447    }
 448
 449    if (!legal_blend_equation(ctx, modeRGB)) {
 450       _mesa_error(ctx, GL_INVALID_ENUM, "glBlendEquationSeparateEXT(modeRGB)");
 451       return;
 452    }
 453
 454    if (!legal_blend_equation(ctx, modeA)) {
 455       _mesa_error(ctx, GL_INVALID_ENUM, "glBlendEquationSeparateEXT(modeA)");
 456       return;
 457    }
 458
 459    numBuffers = ctx->Extensions.ARB_draw_buffers_blend
 460       ? ctx->Const.MaxDrawBuffers : 1;
 461
 462    changed = GL_FALSE;
 463    for (buf = 0; buf < numBuffers; buf++) {
 464       if (ctx->Color.Blend[buf].EquationRGB != modeRGB ||
 465           ctx->Color.Blend[buf].EquationA != modeA) {
 466          changed = GL_TRUE;
 467          break;
 468       }
 469    }
 470    if (!changed)
 471       return;
 472
 473    FLUSH_VERTICES(ctx, _NEW_COLOR);
 474    for (buf = 0; buf < numBuffers; buf++) {
 475       ctx->Color.Blend[buf].EquationRGB = modeRGB;
 476       ctx->Color.Blend[buf].EquationA = modeA;
 477    }
 478    ctx->Color._BlendEquationPerBuffer = GL_FALSE;
 479
 480    if (ctx->Driver.BlendEquationSeparate)
 481       ctx->Driver.BlendEquationSeparate(ctx, modeRGB, modeA);
 482 }
 483
 484
 485 /**
 486  * Set separate blend equations for one color buffer/target.
 487  */
 488 void GLAPIENTRY
 489 _mesa_BlendEquationSeparateiARB(GLuint buf, GLenum modeRGB, GLenum modeA)
 490 {
 491    GET_CURRENT_CONTEXT(ctx);
 492
 493    if (MESA_VERBOSE & VERBOSE_API)
 494       _mesa_debug(ctx, "glBlendEquationSeparatei(%u, %s %s)\n", buf,
 495                   _mesa_enum_to_string(modeRGB),
 496                   _mesa_enum_to_string(modeA));
 497
 498    if (buf >= ctx->Const.MaxDrawBuffers) {
 499       _mesa_error(ctx, GL_INVALID_VALUE, "glBlendEquationSeparatei(buffer=%u)",
 500                   buf);
 501       return;
 502    }
 503
 504    if (!legal_blend_equation(ctx, modeRGB)) {
 505       _mesa_error(ctx, GL_INVALID_ENUM, "glBlendEquationSeparatei(modeRGB)");
 506       return;
 507    }
 508
 509    if (!legal_blend_equation(ctx, modeA)) {
 510       _mesa_error(ctx, GL_INVALID_ENUM, "glBlendEquationSeparatei(modeA)");
 511       return;
 512    }
 513
 514    if (ctx->Color.Blend[buf].EquationRGB == modeRGB &&
 515        ctx->Color.Blend[buf].EquationA == modeA)
 516       return;  /* no change */
 517
 518    FLUSH_VERTICES(ctx, _NEW_COLOR);
 519    ctx->Color.Blend[buf].EquationRGB = modeRGB;
 520    ctx->Color.Blend[buf].EquationA = modeA;
 521    ctx->Color._BlendEquationPerBuffer = GL_TRUE;
 522 }
 523
 524
 525 /**
 526  * Set the blending color.
 527  *
 528  * \param red red color component.
 529  * \param green green color component.
 530  * \param blue blue color component.
 531  * \param alpha alpha color component.
 532  *
 533  * \sa glBlendColor().
 534  *
 535  * Clamps the parameters and updates gl_colorbuffer_attrib::BlendColor.  On a
 536  * change, flushes the vertices and notifies the driver via
 537  * dd_function_table::BlendColor callback.
 538  */
 539 void GLAPIENTRY
 540 _mesa_BlendColor( GLclampf red, GLclampf green, GLclampf blue, GLclampf alpha )
 541 {
 542    GLfloat tmp[4];
 543    GET_CURRENT_CONTEXT(ctx);
 544
 545    tmp[0] = red;
 546    tmp[1] = green;
 547    tmp[2] = blue;
 548    tmp[3] = alpha;
 549
 550    if (TEST_EQ_4V(tmp, ctx->Color.BlendColorUnclamped))
 551       return;
 552
 553    FLUSH_VERTICES(ctx, _NEW_COLOR);
 554    COPY_4FV( ctx->Color.BlendColorUnclamped, tmp );
 555
 556    ctx->Color.BlendColor[0] = CLAMP(tmp[0], 0.0F, 1.0F);
 557    ctx->Color.BlendColor[1] = CLAMP(tmp[1], 0.0F, 1.0F);
 558    ctx->Color.BlendColor[2] = CLAMP(tmp[2], 0.0F, 1.0F);
 559    ctx->Color.BlendColor[3] = CLAMP(tmp[3], 0.0F, 1.0F);
 560
 561    if (ctx->Driver.BlendColor)
 562       (*ctx->Driver.BlendColor)(ctx, ctx->Color.BlendColor);
 563 }
 564
 565
 566 /**
 567  * Specify the alpha test function.
 568  *
 569  * \param func alpha comparison function.
 570  * \param ref reference value.
 571  *
 572  * Verifies the parameters and updates gl_colorbuffer_attrib.
 573  * On a change, flushes the vertices and notifies the driver via
 574  * dd_function_table::AlphaFunc callback.
 575  */
 576 void GLAPIENTRY
 577 _mesa_AlphaFunc( GLenum func, GLclampf ref )
 578 {
 579    GET_CURRENT_CONTEXT(ctx);
 580
 581    if (MESA_VERBOSE & VERBOSE_API)
 582       _mesa_debug(ctx, "glAlphaFunc(%s, %f)\n",
 583                   _mesa_enum_to_string(func), ref);
 584
 585    if (ctx->Color.AlphaFunc == func && ctx->Color.AlphaRefUnclamped == ref)
 586       return; /* no change */
 587
 588    switch (func) {
 589    case GL_NEVER:
 590    case GL_LESS:
 591    case GL_EQUAL:
 592    case GL_LEQUAL:
 593    case GL_GREATER:
 594    case GL_NOTEQUAL:
 595    case GL_GEQUAL:
 596    case GL_ALWAYS:
 597       FLUSH_VERTICES(ctx, _NEW_COLOR);
 598       ctx->Color.AlphaFunc = func;
 599       ctx->Color.AlphaRefUnclamped = ref;
 600       ctx->Color.AlphaRef = CLAMP(ref, 0.0F, 1.0F);
 601
 602       if (ctx->Driver.AlphaFunc)
 603          ctx->Driver.AlphaFunc(ctx, func, ctx->Color.AlphaRef);
 604       return;
 605
 606    default:
 607       _mesa_error( ctx, GL_INVALID_ENUM, "glAlphaFunc(func)" );
 608       return;
 609    }
 610 }
 611
 612
 613 /**
 614  * Specify a logic pixel operation for color index rendering.
 615  *
 616  * \param opcode operation.
 617  *
 618  * Verifies that \p opcode is a valid enum and updates
 619 gl_colorbuffer_attrib::LogicOp.
 620  * On a change, flushes the vertices and notifies the driver via the
 621  * dd_function_table::LogicOpcode callback.
 622  */
 623 void GLAPIENTRY
 624 _mesa_LogicOp( GLenum opcode )
 625 {
 626    GET_CURRENT_CONTEXT(ctx);
 627
 628    if (MESA_VERBOSE & VERBOSE_API)
 629       _mesa_debug(ctx, "glLogicOp(%s)\n", _mesa_enum_to_string(opcode));
 630
 631    switch (opcode) {
 632       case GL_CLEAR:
 633       case GL_SET:
 634       case GL_COPY:
 635       case GL_COPY_INVERTED:
 636       case GL_NOOP:
 637       case GL_INVERT:
 638       case GL_AND:
 639       case GL_NAND:
 640       case GL_OR:
 641       case GL_NOR:
 642       case GL_XOR:
 643       case GL_EQUIV:
 644       case GL_AND_REVERSE:
 645       case GL_AND_INVERTED:
 646       case GL_OR_REVERSE:
 647       case GL_OR_INVERTED:
 648          break;
 649       default:
 650          _mesa_error( ctx, GL_INVALID_ENUM, "glLogicOp" );
 651          return;
 652    }
 653
 654    if (ctx->Color.LogicOp == opcode)
 655       return;
 656
 657    FLUSH_VERTICES(ctx, _NEW_COLOR);
 658    ctx->Color.LogicOp = opcode;
 659
 660    if (ctx->Driver.LogicOpcode)
 661       ctx->Driver.LogicOpcode( ctx, opcode );
 662 }
 663
 664
 665 void GLAPIENTRY
 666 _mesa_IndexMask( GLuint mask )
 667 {
 668    GET_CURRENT_CONTEXT(ctx);
 669
 670    if (ctx->Color.IndexMask == mask)
 671       return;
 672
 673    FLUSH_VERTICES(ctx, _NEW_COLOR);
 674    ctx->Color.IndexMask = mask;
 675 }
 676
 677
 678 /**
 679  * Enable or disable writing of frame buffer color components.
 680  *
 681  * \param red whether to mask writing of the red color component.
 682  * \param green whether to mask writing of the green color component.
 683  * \param blue whether to mask writing of the blue color component.
 684  * \param alpha whether to mask writing of the alpha color component.
 685  *
 686  * \sa glColorMask().
 687  *
 688  * Sets the appropriate value of gl_colorbuffer_attrib::ColorMask.  On a
 689  * change, flushes the vertices and notifies the driver via the
 690  * dd_function_table::ColorMask callback.
 691  */
 692 void GLAPIENTRY
 693 _mesa_ColorMask( GLboolean red, GLboolean green,
 694                  GLboolean blue, GLboolean alpha )
 695 {
 696    GET_CURRENT_CONTEXT(ctx);
 697    GLubyte tmp[4];
 698    GLuint i;
 699    GLboolean flushed;
 700
 701    if (MESA_VERBOSE & VERBOSE_API)
 702       _mesa_debug(ctx, "glColorMask(%d, %d, %d, %d)\n",
 703                   red, green, blue, alpha);
 704
 705    /* Shouldn't have any information about channel depth in core mesa
 706     * -- should probably store these as the native booleans:
 707     */
 708    tmp[RCOMP] = red    ? 0xff : 0x0;
 709    tmp[GCOMP] = green  ? 0xff : 0x0;
 710    tmp[BCOMP] = blue   ? 0xff : 0x0;
 711    tmp[ACOMP] = alpha  ? 0xff : 0x0;
 712
 713    flushed = GL_FALSE;
 714    for (i = 0; i < ctx->Const.MaxDrawBuffers; i++) {
 715       if (!TEST_EQ_4V(tmp, ctx->Color.ColorMask[i])) {
 716          if (!flushed) {
 717             FLUSH_VERTICES(ctx, _NEW_COLOR);
 718          }
 719          flushed = GL_TRUE;
 720          COPY_4UBV(ctx->Color.ColorMask[i], tmp);
 721       }
 722    }
 723
 724    if (ctx->Driver.ColorMask)
 725       ctx->Driver.ColorMask( ctx, red, green, blue, alpha );
 726 }
 727
 728
 729 /**
 730  * For GL_EXT_draw_buffers2 and GL3
 731  */
 732 void GLAPIENTRY
 733 _mesa_ColorMaski( GLuint buf, GLboolean red, GLboolean green,
 734                         GLboolean blue, GLboolean alpha )
 735 {
 736    GLubyte tmp[4];
 737    GET_CURRENT_CONTEXT(ctx);
 738
 739    if (MESA_VERBOSE & VERBOSE_API)
 740       _mesa_debug(ctx, "glColorMaskIndexed %u %d %d %d %d\n",
 741                   buf, red, green, blue, alpha);
 742
 743    if (buf >= ctx->Const.MaxDrawBuffers) {
 744       _mesa_error(ctx, GL_INVALID_VALUE, "glColorMaskIndexed(buf=%u)", buf);
 745       return;
 746    }
 747
 748    /* Shouldn't have any information about channel depth in core mesa
 749     * -- should probably store these as the native booleans:
 750     */
 751    tmp[RCOMP] = red    ? 0xff : 0x0;
 752    tmp[GCOMP] = green  ? 0xff : 0x0;
 753    tmp[BCOMP] = blue   ? 0xff : 0x0;
 754    tmp[ACOMP] = alpha  ? 0xff : 0x0;
 755
 756    if (TEST_EQ_4V(tmp, ctx->Color.ColorMask[buf]))
 757       return;
 758
 759    FLUSH_VERTICES(ctx, _NEW_COLOR);
 760    COPY_4UBV(ctx->Color.ColorMask[buf], tmp);
 761 }
 762
 763
 764 void GLAPIENTRY
 765 _mesa_ClampColor(GLenum target, GLenum clamp)
 766 {
 767    GET_CURRENT_CONTEXT(ctx);
 768
 769    if (clamp != GL_TRUE && clamp != GL_FALSE && clamp != GL_FIXED_ONLY_ARB) {
 770       _mesa_error(ctx, GL_INVALID_ENUM, "glClampColorARB(clamp)");
 771       return;
 772    }
 773
 774    switch (target) {
 775    case GL_CLAMP_VERTEX_COLOR_ARB:
 776       if (ctx->API == API_OPENGL_CORE &&
 777           !ctx->Extensions.ARB_color_buffer_float) {
 778          goto invalid_enum;
 779       }
 780       FLUSH_VERTICES(ctx, _NEW_LIGHT);
 781       ctx->Light.ClampVertexColor = clamp;
 782       _mesa_update_clamp_vertex_color(ctx, ctx->DrawBuffer);
 783       break;
 784    case GL_CLAMP_FRAGMENT_COLOR_ARB:
 785       if (ctx->API == API_OPENGL_CORE &&
 786           !ctx->Extensions.ARB_color_buffer_float) {
 787          goto invalid_enum;
 788       }
 789       FLUSH_VERTICES(ctx, _NEW_FRAG_CLAMP);
 790       ctx->Color.ClampFragmentColor = clamp;
 791       _mesa_update_clamp_fragment_color(ctx, ctx->DrawBuffer);
 792       break;
 793    case GL_CLAMP_READ_COLOR_ARB:
 794       ctx->Color.ClampReadColor = clamp;
 795       break;
 796    default:
 797       goto invalid_enum;
 798    }
 799    return;
 800
 801 invalid_enum:
 802    _mesa_error(ctx, GL_INVALID_ENUM, "glClampColor(%s)",
 803                _mesa_enum_to_string(target));
 804 }
 805
 806 static GLboolean
 807 get_clamp_color(const struct gl_framebuffer *fb, GLenum clamp)
 808 {
 809    if (clamp == GL_TRUE || clamp == GL_FALSE)
 810       return clamp;
 811
 812    assert(clamp == GL_FIXED_ONLY);
 813    if (!fb)
 814       return GL_TRUE;
 815
 816    return fb->_AllColorBuffersFixedPoint;
 817 }
 818
 819 GLboolean
 820 _mesa_get_clamp_fragment_color(const struct gl_context *ctx,
 821                                const struct gl_framebuffer *drawFb)
 822 {
 823    return get_clamp_color(drawFb, ctx->Color.ClampFragmentColor);
 824 }
 825
 826 GLboolean
 827 _mesa_get_clamp_vertex_color(const struct gl_context *ctx,
 828                              const struct gl_framebuffer *drawFb)
 829 {
 830    return get_clamp_color(drawFb, ctx->Light.ClampVertexColor);
 831 }
 832
 833 GLboolean
 834 _mesa_get_clamp_read_color(const struct gl_context *ctx,
 835                            const struct gl_framebuffer *readFb)
 836 {
 837    return get_clamp_color(readFb, ctx->Color.ClampReadColor);
 838 }
 839
 840 /**
 841  * Update the ctx->Color._ClampFragmentColor field
 842  */
 843 void
 844 _mesa_update_clamp_fragment_color(struct gl_context *ctx,
 845                                   const struct gl_framebuffer *drawFb)
 846 {
 847    /* Don't clamp if:
 848     * - there is no colorbuffer
 849     * - all colorbuffers are unsigned normalized, so clamping has no effect
 850     * - there is an integer colorbuffer
 851     */
 852    if (!drawFb || !drawFb->_HasSNormOrFloatColorBuffer ||
 853        drawFb->_IntegerColor)
 854       ctx->Color._ClampFragmentColor = GL_FALSE;
 855    else
 856       ctx->Color._ClampFragmentColor =
 857          _mesa_get_clamp_fragment_color(ctx, drawFb);
 858 }
 859
 860 /**
 861  * Update the ctx->Color._ClampVertexColor field
 862  */
 863 void
 864 _mesa_update_clamp_vertex_color(struct gl_context *ctx,
 865                                 const struct gl_framebuffer *drawFb)
 866 {
 867    ctx->Light._ClampVertexColor =
 868          _mesa_get_clamp_vertex_color(ctx, drawFb);
 869 }
 870
 871 /**
 872  * Returns an appropriate mesa_format for color rendering based on the
 873  * GL_FRAMEBUFFER_SRGB state.
 874  *
 875  * Some drivers implement GL_FRAMEBUFFER_SRGB using a flag on the blend state
 876  * (which GL_FRAMEBUFFER_SRGB maps to reasonably), but some have to do so by
 877  * overriding the format of the surface.  This is a helper for doing the
 878  * surface format override variant.
 879  */
 880 mesa_format
 881 _mesa_get_render_format(const struct gl_context *ctx, mesa_format format)
 882 {
 883    if (ctx->Color.sRGBEnabled)
 884       return format;
 885    else
 886       return _mesa_get_srgb_format_linear(format);
 887 }
 888
 889 /**********************************************************************/
 890 /** \name Initialization */
 891 /*@{*/
 892
 893 /**
 894  * Initialization of the context's Color attribute group.
 895  *
 896  * \param ctx GL context.
 897  *
 898  * Initializes the related fields in the context color attribute group,
 899  * __struct gl_contextRec::Color.
 900  */
 901 void _mesa_init_color( struct gl_context * ctx )
 902 {
 903    GLuint i;
 904
 905    /* Color buffer group */
 906    ctx->Color.IndexMask = ~0u;
 907    memset(ctx->Color.ColorMask, 0xff, sizeof(ctx->Color.ColorMask));
 908    ctx->Color.ClearIndex = 0;
 909    ASSIGN_4V( ctx->Color.ClearColor.f, 0, 0, 0, 0 );
 910    ctx->Color.AlphaEnabled = GL_FALSE;
 911    ctx->Color.AlphaFunc = GL_ALWAYS;
 912    ctx->Color.AlphaRef = 0;
 913    ctx->Color.BlendEnabled = 0x0;
 914    for (i = 0; i < ARRAY_SIZE(ctx->Color.Blend); i++) {
 915       ctx->Color.Blend[i].SrcRGB = GL_ONE;
 916       ctx->Color.Blend[i].DstRGB = GL_ZERO;
 917       ctx->Color.Blend[i].SrcA = GL_ONE;
 918       ctx->Color.Blend[i].DstA = GL_ZERO;
 919       ctx->Color.Blend[i].EquationRGB = GL_FUNC_ADD;
 920       ctx->Color.Blend[i].EquationA = GL_FUNC_ADD;
 921    }
 922    ASSIGN_4V( ctx->Color.BlendColor, 0.0, 0.0, 0.0, 0.0 );
 923    ASSIGN_4V( ctx->Color.BlendColorUnclamped, 0.0, 0.0, 0.0, 0.0 );
 924    ctx->Color.IndexLogicOpEnabled = GL_FALSE;
 925    ctx->Color.ColorLogicOpEnabled = GL_FALSE;
 926    ctx->Color.LogicOp = GL_COPY;
 927    ctx->Color.DitherFlag = GL_TRUE;
 928
 929    /* GL_FRONT is not possible on GLES. Instead GL_BACK will render to either
 930     * the front or the back buffer depending on the config */
 931    if (ctx->Visual.doubleBufferMode || _mesa_is_gles(ctx)) {
 932       ctx->Color.DrawBuffer[0] = GL_BACK;
 933    }
 934    else {
 935       ctx->Color.DrawBuffer[0] = GL_FRONT;
 936    }
 937
 938    ctx->Color.ClampFragmentColor = ctx->API == API_OPENGL_COMPAT ?
 939                                    GL_FIXED_ONLY_ARB : GL_FALSE;
 940    ctx->Color._ClampFragmentColor = GL_FALSE;
 941    ctx->Color.ClampReadColor = GL_FIXED_ONLY_ARB;
 942
 943    /* GLES 1/2/3 behaves as though GL_FRAMEBUFFER_SRGB is always enabled
 944     * if EGL_KHR_gl_colorspace has been used to request sRGB.
 945     */
 946    ctx->Color.sRGBEnabled = _mesa_is_gles(ctx);
 947 }
 948
 949 /*@}*/