reactos/dll/opengl/mesa/main/stencil.c

   1 /*
   2  * Mesa 3-D graphics library
   3  * Version:  7.1
   4  *
   5  * Copyright (C) 1999-2007  Brian Paul   All Rights Reserved.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a
   8  * copy of this software and associated documentation files (the "Software"),
   9  * to deal in the Software without restriction, including without limitation
  10  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  11  * and/or sell copies of the Software, and to permit persons to whom the
  12  * Software is furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included
  15  * in all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  18  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  20  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  21  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  22  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  23  */
  24
  25
  26 /**
  27  * \file stencil.c
  28  * Stencil operations.
  29  *
  30  * Note: There's some conflict between GL_EXT_stencil_two_side and
  31  * OpenGL 2.0's two-sided stencil feature.
  32  *
  33  * With GL_EXT_stencil_two_side, calling glStencilOp/Func/Mask() only the
  34  * front OR back face state (as set by glActiveStencilFaceEXT) is set.
  35  *
  36  * But with OpenGL 2.0, calling glStencilOp/Func/Mask() sets BOTH the
  37  * front AND back state.
  38  *
  39  * Also, note that GL_ATI_separate_stencil is different as well:
  40  * glStencilFuncSeparateATI(GLenum frontfunc, GLenum backfunc, ...)  vs.
  41  * glStencilFuncSeparate(GLenum face, GLenum func, ...).
  42  *
  43  * This problem is solved by keeping three sets of stencil state:
  44  *  state[0] = GL_FRONT state.
  45  *  state[1] = OpenGL 2.0 / GL_ATI_separate_stencil GL_BACK state.
  46  *  state[2] = GL_EXT_stencil_two_side GL_BACK state.
  47  */
  48
  49
  50 #include "glheader.h"
  51 #include "imports.h"
  52 #include "context.h"
  53 #include "macros.h"
  54 #include "stencil.h"
  55 #include "mtypes.h"
  56
  57
  58 static GLboolean
  59 validate_stencil_op(struct gl_context *ctx, GLenum op)
  60 {
  61    switch (op) {
  62    case GL_KEEP:
  63    case GL_ZERO:
  64    case GL_REPLACE:
  65    case GL_INCR:
  66    case GL_DECR:
  67    case GL_INVERT:
  68    case GL_INCR_WRAP:
  69    case GL_DECR_WRAP:
  70       return GL_TRUE;
  71    default:
  72       return GL_FALSE;
  73    }
  74 }
  75
  76
  77 static GLboolean
  78 validate_stencil_func(struct gl_context *ctx, GLenum func)
  79 {
  80    switch (func) {
  81    case GL_NEVER:
  82    case GL_LESS:
  83    case GL_LEQUAL:
  84    case GL_GREATER:
  85    case GL_GEQUAL:
  86    case GL_EQUAL:
  87    case GL_NOTEQUAL:
  88    case GL_ALWAYS:
  89       return GL_TRUE;
  90    default:
  91       return GL_FALSE;
  92    }
  93 }
  94
  95
  96 /**
  97  * Set the clear value for the stencil buffer.
  98  *
  99  * \param s clear value.
 100  *
 101  * \sa glClearStencil().
 102  *
 103  * Updates gl_stencil_attrib::Clear. On change
 104  * flushes the vertices and notifies the driver via
 105  * the dd_function_table::ClearStencil callback.
 106  */
 107 void GLAPIENTRY
 108 _mesa_ClearStencil( GLint s )
 109 {
 110    GET_CURRENT_CONTEXT(ctx);
 111    ASSERT_OUTSIDE_BEGIN_END(ctx);
 112
 113    if (ctx->Stencil.Clear == (GLuint) s)
 114       return;
 115
 116    FLUSH_VERTICES(ctx, _NEW_STENCIL);
 117    ctx->Stencil.Clear = (GLuint) s;
 118
 119    if (ctx->Driver.ClearStencil) {
 120       ctx->Driver.ClearStencil( ctx, s );
 121    }
 122 }
 123
 124
 125 /**
 126  * Set the function and reference value for stencil testing.
 127  *
 128  * \param frontfunc front test function.
 129  * \param backfunc back test function.
 130  * \param ref front and back reference value.
 131  * \param mask front and back bitmask.
 132  *
 133  * \sa glStencilFunc().
 134  *
 135  * Verifies the parameters and updates the respective values in
 136  * __struct gl_contextRec::Stencil. On change flushes the vertices and notifies the
 137  * driver via the dd_function_table::StencilFunc callback.
 138  */
 139 void GLAPIENTRY
 140 _mesa_StencilFuncSeparateATI( GLenum frontfunc, GLenum backfunc, GLint ref, GLuint mask )
 141 {
 142    GET_CURRENT_CONTEXT(ctx);
 143    const GLint stencilMax = (1 << ctx->DrawBuffer->Visual.stencilBits) - 1;
 144    ASSERT_OUTSIDE_BEGIN_END(ctx);
 145
 146    if (MESA_VERBOSE & VERBOSE_API)
 147       _mesa_debug(ctx, "glStencilFuncSeparateATI()\n");
 148
 149    if (!validate_stencil_func(ctx, frontfunc)) {
 150       _mesa_error(ctx, GL_INVALID_ENUM,
 151                   "glStencilFuncSeparateATI(frontfunc)");
 152       return;
 153    }
 154    if (!validate_stencil_func(ctx, backfunc)) {
 155       _mesa_error(ctx, GL_INVALID_ENUM,
 156                   "glStencilFuncSeparateATI(backfunc)");
 157       return;
 158    }
 159
 160    ref = CLAMP( ref, 0, stencilMax );
 161
 162    /* set both front and back state */
 163    if (ctx->Stencil.Function[0] == frontfunc &&
 164        ctx->Stencil.Function[1] == backfunc &&
 165        ctx->Stencil.ValueMask[0] == mask &&
 166        ctx->Stencil.ValueMask[1] == mask &&
 167        ctx->Stencil.Ref[0] == ref &&
 168        ctx->Stencil.Ref[1] == ref)
 169       return;
 170    FLUSH_VERTICES(ctx, _NEW_STENCIL);
 171    ctx->Stencil.Function[0]  = frontfunc;
 172    ctx->Stencil.Function[1]  = backfunc;
 173    ctx->Stencil.Ref[0]       = ctx->Stencil.Ref[1]       = ref;
 174    ctx->Stencil.ValueMask[0] = ctx->Stencil.ValueMask[1] = mask;
 175    if (ctx->Driver.StencilFuncSeparate) {
 176       ctx->Driver.StencilFuncSeparate(ctx, GL_FRONT,
 177                                       frontfunc, ref, mask);
 178       ctx->Driver.StencilFuncSeparate(ctx, GL_BACK,
 179                                       backfunc, ref, mask);
 180    }
 181 }
 182
 183
 184 /**
 185  * Set the function and reference value for stencil testing.
 186  *
 187  * \param func test function.
 188  * \param ref reference value.
 189  * \param mask bitmask.
 190  *
 191  * \sa glStencilFunc().
 192  *
 193  * Verifies the parameters and updates the respective values in
 194  * __struct gl_contextRec::Stencil. On change flushes the vertices and notifies the
 195  * driver via the dd_function_table::StencilFunc callback.
 196  */
 197 void GLAPIENTRY
 198 _mesa_StencilFunc( GLenum func, GLint ref, GLuint mask )
 199 {
 200    GET_CURRENT_CONTEXT(ctx);
 201    const GLint stencilMax = (1 << ctx->DrawBuffer->Visual.stencilBits) - 1;
 202    const GLint face = ctx->Stencil.ActiveFace;
 203    ASSERT_OUTSIDE_BEGIN_END(ctx);
 204
 205    if (MESA_VERBOSE & VERBOSE_API)
 206       _mesa_debug(ctx, "glStencilFunc()\n");
 207
 208    if (!validate_stencil_func(ctx, func)) {
 209       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilFunc(func)");
 210       return;
 211    }
 212
 213    ref = CLAMP( ref, 0, stencilMax );
 214
 215    if (face != 0) {
 216       if (ctx->Stencil.Function[face] == func &&
 217           ctx->Stencil.ValueMask[face] == mask &&
 218           ctx->Stencil.Ref[face] == ref)
 219          return;
 220       FLUSH_VERTICES(ctx, _NEW_STENCIL);
 221       ctx->Stencil.Function[face] = func;
 222       ctx->Stencil.Ref[face] = ref;
 223       ctx->Stencil.ValueMask[face] = mask;
 224
 225       /* Only propagate the change to the driver if EXT_stencil_two_side
 226        * is enabled.
 227        */
 228       if (ctx->Driver.StencilFuncSeparate && ctx->Stencil.TestTwoSide) {
 229          ctx->Driver.StencilFuncSeparate(ctx, GL_BACK, func, ref, mask);
 230       }
 231    }
 232    else {
 233       /* set both front and back state */
 234       if (ctx->Stencil.Function[0] == func &&
 235           ctx->Stencil.Function[1] == func &&
 236           ctx->Stencil.ValueMask[0] == mask &&
 237           ctx->Stencil.ValueMask[1] == mask &&
 238           ctx->Stencil.Ref[0] == ref &&
 239           ctx->Stencil.Ref[1] == ref)
 240          return;
 241       FLUSH_VERTICES(ctx, _NEW_STENCIL);
 242       ctx->Stencil.Function[0]  = ctx->Stencil.Function[1]  = func;
 243       ctx->Stencil.Ref[0]       = ctx->Stencil.Ref[1]       = ref;
 244       ctx->Stencil.ValueMask[0] = ctx->Stencil.ValueMask[1] = mask;
 245       if (ctx->Driver.StencilFuncSeparate) {
 246          ctx->Driver.StencilFuncSeparate(ctx,
 247                                          ((ctx->Stencil.TestTwoSide)
 248                                           ? GL_FRONT : GL_FRONT_AND_BACK),
 249                                          func, ref, mask);
 250       }
 251    }
 252 }
 253
 254
 255 /**
 256  * Set the stencil writing mask.
 257  *
 258  * \param mask bit-mask to enable/disable writing of individual bits in the
 259  * stencil planes.
 260  *
 261  * \sa glStencilMask().
 262  *
 263  * Updates gl_stencil_attrib::WriteMask. On change flushes the vertices and
 264  * notifies the driver via the dd_function_table::StencilMask callback.
 265  */
 266 void GLAPIENTRY
 267 _mesa_StencilMask( GLuint mask )
 268 {
 269    GET_CURRENT_CONTEXT(ctx);
 270    const GLint face = ctx->Stencil.ActiveFace;
 271
 272    if (MESA_VERBOSE & VERBOSE_API)
 273       _mesa_debug(ctx, "glStencilMask()\n");
 274
 275    ASSERT_OUTSIDE_BEGIN_END(ctx);
 276
 277    if (face != 0) {
 278       /* Only modify the EXT_stencil_two_side back-face state.
 279        */
 280       if (ctx->Stencil.WriteMask[face] == mask)
 281          return;
 282       FLUSH_VERTICES(ctx, _NEW_STENCIL);
 283       ctx->Stencil.WriteMask[face] = mask;
 284
 285       /* Only propagate the change to the driver if EXT_stencil_two_side
 286        * is enabled.
 287        */
 288       if (ctx->Driver.StencilMaskSeparate && ctx->Stencil.TestTwoSide) {
 289          ctx->Driver.StencilMaskSeparate(ctx, GL_BACK, mask);
 290       }
 291    }
 292    else {
 293       /* set both front and back state */
 294       if (ctx->Stencil.WriteMask[0] == mask &&
 295           ctx->Stencil.WriteMask[1] == mask)
 296          return;
 297       FLUSH_VERTICES(ctx, _NEW_STENCIL);
 298       ctx->Stencil.WriteMask[0] = ctx->Stencil.WriteMask[1] = mask;
 299       if (ctx->Driver.StencilMaskSeparate) {
 300          ctx->Driver.StencilMaskSeparate(ctx,
 301                                          ((ctx->Stencil.TestTwoSide)
 302                                           ? GL_FRONT : GL_FRONT_AND_BACK),
 303                                           mask);
 304       }
 305    }
 306 }
 307
 308
 309 /**
 310  * Set the stencil test actions.
 311  *
 312  * \param fail action to take when stencil test fails.
 313  * \param zfail action to take when stencil test passes, but depth test fails.
 314  * \param zpass action to take when stencil test passes and the depth test
 315  * passes (or depth testing is not enabled).
 316  *
 317  * \sa glStencilOp().
 318  *
 319  * Verifies the parameters and updates the respective fields in
 320  * __struct gl_contextRec::Stencil. On change flushes the vertices and notifies the
 321  * driver via the dd_function_table::StencilOp callback.
 322  */
 323 void GLAPIENTRY
 324 _mesa_StencilOp(GLenum fail, GLenum zfail, GLenum zpass)
 325 {
 326    GET_CURRENT_CONTEXT(ctx);
 327    const GLint face = ctx->Stencil.ActiveFace;
 328
 329    if (MESA_VERBOSE & VERBOSE_API)
 330       _mesa_debug(ctx, "glStencilOp()\n");
 331
 332    ASSERT_OUTSIDE_BEGIN_END(ctx);
 333
 334    if (!validate_stencil_op(ctx, fail)) {
 335       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOp(sfail)");
 336       return;
 337    }
 338    if (!validate_stencil_op(ctx, zfail)) {
 339       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOp(zfail)");
 340       return;
 341    }
 342    if (!validate_stencil_op(ctx, zpass)) {
 343       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOp(zpass)");
 344       return;
 345    }
 346
 347    if (face != 0) {
 348       /* only set active face state */
 349       if (ctx->Stencil.ZFailFunc[face] == zfail &&
 350           ctx->Stencil.ZPassFunc[face] == zpass &&
 351           ctx->Stencil.FailFunc[face] == fail)
 352          return;
 353       FLUSH_VERTICES(ctx, _NEW_STENCIL);
 354       ctx->Stencil.ZFailFunc[face] = zfail;
 355       ctx->Stencil.ZPassFunc[face] = zpass;
 356       ctx->Stencil.FailFunc[face] = fail;
 357
 358       /* Only propagate the change to the driver if EXT_stencil_two_side
 359        * is enabled.
 360        */
 361       if (ctx->Driver.StencilOpSeparate && ctx->Stencil.TestTwoSide) {
 362          ctx->Driver.StencilOpSeparate(ctx, GL_BACK, fail, zfail, zpass);
 363       }
 364    }
 365    else {
 366       /* set both front and back state */
 367       if (ctx->Stencil.ZFailFunc[0] == zfail &&
 368           ctx->Stencil.ZFailFunc[1] == zfail &&
 369           ctx->Stencil.ZPassFunc[0] == zpass &&
 370           ctx->Stencil.ZPassFunc[1] == zpass &&
 371           ctx->Stencil.FailFunc[0] == fail &&
 372           ctx->Stencil.FailFunc[1] == fail)
 373          return;
 374       FLUSH_VERTICES(ctx, _NEW_STENCIL);
 375       ctx->Stencil.ZFailFunc[0] = ctx->Stencil.ZFailFunc[1] = zfail;
 376       ctx->Stencil.ZPassFunc[0] = ctx->Stencil.ZPassFunc[1] = zpass;
 377       ctx->Stencil.FailFunc[0]  = ctx->Stencil.FailFunc[1]  = fail;
 378       if (ctx->Driver.StencilOpSeparate) {
 379          ctx->Driver.StencilOpSeparate(ctx,
 380                                        ((ctx->Stencil.TestTwoSide)
 381                                         ? GL_FRONT : GL_FRONT_AND_BACK),
 382                                        fail, zfail, zpass);
 383       }
 384    }
 385 }
 386
 387
 388
 389 #if _HAVE_FULL_GL
 390 /* GL_EXT_stencil_two_side */
 391 void GLAPIENTRY
 392 _mesa_ActiveStencilFaceEXT(GLenum face)
 393 {
 394    GET_CURRENT_CONTEXT(ctx);
 395    ASSERT_OUTSIDE_BEGIN_END(ctx);
 396
 397    if (MESA_VERBOSE & VERBOSE_API)
 398       _mesa_debug(ctx, "glActiveStencilFaceEXT()\n");
 399
 400    if (!ctx->Extensions.EXT_stencil_two_side) {
 401       _mesa_error(ctx, GL_INVALID_OPERATION, "glActiveStencilFaceEXT");
 402       return;
 403    }
 404
 405    if (face == GL_FRONT || face == GL_BACK) {
 406       FLUSH_VERTICES(ctx, _NEW_STENCIL);
 407       ctx->Stencil.ActiveFace = (face == GL_FRONT) ? 0 : 2;
 408    }
 409    else {
 410       _mesa_error(ctx, GL_INVALID_ENUM, "glActiveStencilFaceEXT(face)");
 411    }
 412 }
 413 #endif
 414
 415
 416
 417 /**
 418  * OpenGL 2.0 function.
 419  * \todo Make StencilOp() call this function.  And eventually remove the
 420  * ctx->Driver.StencilOp function and use ctx->Driver.StencilOpSeparate
 421  * instead.
 422  */
 423 void GLAPIENTRY
 424 _mesa_StencilOpSeparate(GLenum face, GLenum sfail, GLenum zfail, GLenum zpass)
 425 {
 426    GLboolean set = GL_FALSE;
 427    GET_CURRENT_CONTEXT(ctx);
 428    ASSERT_OUTSIDE_BEGIN_END(ctx);
 429
 430    if (MESA_VERBOSE & VERBOSE_API)
 431       _mesa_debug(ctx, "glStencilOpSeparate()\n");
 432
 433    if (!validate_stencil_op(ctx, sfail)) {
 434       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOpSeparate(sfail)");
 435       return;
 436    }
 437    if (!validate_stencil_op(ctx, zfail)) {
 438       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOpSeparate(zfail)");
 439       return;
 440    }
 441    if (!validate_stencil_op(ctx, zpass)) {
 442       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOpSeparate(zpass)");
 443       return;
 444    }
 445    if (face != GL_FRONT && face != GL_BACK && face != GL_FRONT_AND_BACK) {
 446       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOpSeparate(face)");
 447       return;
 448    }
 449
 450    if (face != GL_BACK) {
 451       /* set front */
 452       if (ctx->Stencil.ZFailFunc[0] != zfail ||
 453           ctx->Stencil.ZPassFunc[0] != zpass ||
 454           ctx->Stencil.FailFunc[0] != sfail){
 455          FLUSH_VERTICES(ctx, _NEW_STENCIL);
 456          ctx->Stencil.ZFailFunc[0] = zfail;
 457          ctx->Stencil.ZPassFunc[0] = zpass;
 458          ctx->Stencil.FailFunc[0] = sfail;
 459          set = GL_TRUE;
 460       }
 461    }
 462    if (face != GL_FRONT) {
 463       /* set back */
 464       if (ctx->Stencil.ZFailFunc[1] != zfail ||
 465           ctx->Stencil.ZPassFunc[1] != zpass ||
 466           ctx->Stencil.FailFunc[1] != sfail) {
 467          FLUSH_VERTICES(ctx, _NEW_STENCIL);
 468          ctx->Stencil.ZFailFunc[1] = zfail;
 469          ctx->Stencil.ZPassFunc[1] = zpass;
 470          ctx->Stencil.FailFunc[1] = sfail;
 471          set = GL_TRUE;
 472       }
 473    }
 474    if (set && ctx->Driver.StencilOpSeparate) {
 475       ctx->Driver.StencilOpSeparate(ctx, face, sfail, zfail, zpass);
 476    }
 477 }
 478
 479
 480 /* OpenGL 2.0 */
 481 void GLAPIENTRY
 482 _mesa_StencilFuncSeparate(GLenum face, GLenum func, GLint ref, GLuint mask)
 483 {
 484    GET_CURRENT_CONTEXT(ctx);
 485    const GLint stencilMax = (1 << ctx->DrawBuffer->Visual.stencilBits) - 1;
 486    ASSERT_OUTSIDE_BEGIN_END(ctx);
 487
 488    if (MESA_VERBOSE & VERBOSE_API)
 489       _mesa_debug(ctx, "glStencilFuncSeparate()\n");
 490
 491    if (face != GL_FRONT && face != GL_BACK && face != GL_FRONT_AND_BACK) {
 492       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilFuncSeparate(face)");
 493       return;
 494    }
 495    if (!validate_stencil_func(ctx, func)) {
 496       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilFuncSeparate(func)");
 497       return;
 498    }
 499
 500    ref = CLAMP(ref, 0, stencilMax);
 501
 502    FLUSH_VERTICES(ctx, _NEW_STENCIL);
 503
 504    if (face != GL_BACK) {
 505       /* set front */
 506       ctx->Stencil.Function[0] = func;
 507       ctx->Stencil.Ref[0] = ref;
 508       ctx->Stencil.ValueMask[0] = mask;
 509    }
 510    if (face != GL_FRONT) {
 511       /* set back */
 512       ctx->Stencil.Function[1] = func;
 513       ctx->Stencil.Ref[1] = ref;
 514       ctx->Stencil.ValueMask[1] = mask;
 515    }
 516    if (ctx->Driver.StencilFuncSeparate) {
 517       ctx->Driver.StencilFuncSeparate(ctx, face, func, ref, mask);
 518    }
 519 }
 520
 521
 522 /* OpenGL 2.0 */
 523 void GLAPIENTRY
 524 _mesa_StencilMaskSeparate(GLenum face, GLuint mask)
 525 {
 526    GET_CURRENT_CONTEXT(ctx);
 527    ASSERT_OUTSIDE_BEGIN_END(ctx);
 528
 529    if (MESA_VERBOSE & VERBOSE_API)
 530       _mesa_debug(ctx, "glStencilMaskSeparate()\n");
 531
 532    if (face != GL_FRONT && face != GL_BACK && face != GL_FRONT_AND_BACK) {
 533       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilaMaskSeparate(face)");
 534       return;
 535    }
 536
 537    FLUSH_VERTICES(ctx, _NEW_STENCIL);
 538
 539    if (face != GL_BACK) {
 540       ctx->Stencil.WriteMask[0] = mask;
 541    }
 542    if (face != GL_FRONT) {
 543       ctx->Stencil.WriteMask[1] = mask;
 544    }
 545    if (ctx->Driver.StencilMaskSeparate) {
 546       ctx->Driver.StencilMaskSeparate(ctx, face, mask);
 547    }
 548 }
 549
 550
 551 /**
 552  * Update derived stencil state.
 553  */
 554 void
 555 _mesa_update_stencil(struct gl_context *ctx)
 556 {
 557    const GLint face = ctx->Stencil._BackFace;
 558
 559    ctx->Stencil._Enabled = (ctx->Stencil.Enabled &&
 560                             ctx->DrawBuffer->Visual.stencilBits > 0);
 561
 562     ctx->Stencil._TestTwoSide =
 563        ctx->Stencil._Enabled &&
 564        (ctx->Stencil.Function[0] != ctx->Stencil.Function[face] ||
 565         ctx->Stencil.FailFunc[0] != ctx->Stencil.FailFunc[face] ||
 566         ctx->Stencil.ZPassFunc[0] != ctx->Stencil.ZPassFunc[face] ||
 567         ctx->Stencil.ZFailFunc[0] != ctx->Stencil.ZFailFunc[face] ||
 568         ctx->Stencil.Ref[0] != ctx->Stencil.Ref[face] ||
 569         ctx->Stencil.ValueMask[0] != ctx->Stencil.ValueMask[face] ||
 570         ctx->Stencil.WriteMask[0] != ctx->Stencil.WriteMask[face]);
 571 }
 572
 573
 574 /**
 575  * Initialize the context stipple state.
 576  *
 577  * \param ctx GL context.
 578  *
 579  * Initializes __struct gl_contextRec::Stencil attribute group.
 580  */
 581 void
 582 _mesa_init_stencil(struct gl_context *ctx)
 583 {
 584    ctx->Stencil.Enabled = GL_FALSE;
 585    ctx->Stencil.TestTwoSide = GL_FALSE;
 586    ctx->Stencil.ActiveFace = 0;  /* 0 = GL_FRONT, 2 = GL_BACK */
 587    ctx->Stencil.Function[0] = GL_ALWAYS;
 588    ctx->Stencil.Function[1] = GL_ALWAYS;
 589    ctx->Stencil.Function[2] = GL_ALWAYS;
 590    ctx->Stencil.FailFunc[0] = GL_KEEP;
 591    ctx->Stencil.FailFunc[1] = GL_KEEP;
 592    ctx->Stencil.FailFunc[2] = GL_KEEP;
 593    ctx->Stencil.ZPassFunc[0] = GL_KEEP;
 594    ctx->Stencil.ZPassFunc[1] = GL_KEEP;
 595    ctx->Stencil.ZPassFunc[2] = GL_KEEP;
 596    ctx->Stencil.ZFailFunc[0] = GL_KEEP;
 597    ctx->Stencil.ZFailFunc[1] = GL_KEEP;
 598    ctx->Stencil.ZFailFunc[2] = GL_KEEP;
 599    ctx->Stencil.Ref[0] = 0;
 600    ctx->Stencil.Ref[1] = 0;
 601    ctx->Stencil.Ref[2] = 0;
 602    ctx->Stencil.ValueMask[0] = ~0U;
 603    ctx->Stencil.ValueMask[1] = ~0U;
 604    ctx->Stencil.ValueMask[2] = ~0U;
 605    ctx->Stencil.WriteMask[0] = ~0U;
 606    ctx->Stencil.WriteMask[1] = ~0U;
 607    ctx->Stencil.WriteMask[2] = ~0U;
 608    ctx->Stencil.Clear = 0;
 609    ctx->Stencil._BackFace = 1;
 610 }