src/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       return GL_TRUE;
  69    case GL_INCR_WRAP_EXT:
  70    case GL_DECR_WRAP_EXT:
  71       if (ctx->Extensions.EXT_stencil_wrap) {
  72          return GL_TRUE;
  73       }
  74       /* FALL-THROUGH */
  75    default:
  76       return GL_FALSE;
  77    }
  78 }
  79
  80
  81 static GLboolean
  82 validate_stencil_func(struct gl_context *ctx, GLenum func)
  83 {
  84    switch (func) {
  85    case GL_NEVER:
  86    case GL_LESS:
  87    case GL_LEQUAL:
  88    case GL_GREATER:
  89    case GL_GEQUAL:
  90    case GL_EQUAL:
  91    case GL_NOTEQUAL:
  92    case GL_ALWAYS:
  93       return GL_TRUE;
  94    default:
  95       return GL_FALSE;
  96    }
  97 }
  98
  99
 100 /**
 101  * Set the clear value for the stencil buffer.
 102  *
 103  * \param s clear value.
 104  *
 105  * \sa glClearStencil().
 106  *
 107  * Updates gl_stencil_attrib::Clear. On change
 108  * flushes the vertices and notifies the driver via
 109  * the dd_function_table::ClearStencil callback.
 110  */
 111 void GLAPIENTRY
 112 _mesa_ClearStencil( GLint s )
 113 {
 114    GET_CURRENT_CONTEXT(ctx);
 115    ASSERT_OUTSIDE_BEGIN_END(ctx);
 116
 117    if (ctx->Stencil.Clear == (GLuint) s)
 118       return;
 119
 120    FLUSH_VERTICES(ctx, _NEW_STENCIL);
 121    ctx->Stencil.Clear = (GLuint) s;
 122
 123    if (ctx->Driver.ClearStencil) {
 124       ctx->Driver.ClearStencil( ctx, s );
 125    }
 126 }
 127
 128
 129 /**
 130  * Set the function and reference value for stencil testing.
 131  *
 132  * \param frontfunc front test function.
 133  * \param backfunc back test function.
 134  * \param ref front and back reference value.
 135  * \param mask front and back bitmask.
 136  *
 137  * \sa glStencilFunc().
 138  *
 139  * Verifies the parameters and updates the respective values in
 140  * __struct gl_contextRec::Stencil. On change flushes the vertices and notifies the
 141  * driver via the dd_function_table::StencilFunc callback.
 142  */
 143 void GLAPIENTRY
 144 _mesa_StencilFuncSeparateATI( GLenum frontfunc, GLenum backfunc, GLint ref, GLuint mask )
 145 {
 146    GET_CURRENT_CONTEXT(ctx);
 147    const GLint stencilMax = (1 << ctx->DrawBuffer->Visual.stencilBits) - 1;
 148    ASSERT_OUTSIDE_BEGIN_END(ctx);
 149
 150    if (MESA_VERBOSE & VERBOSE_API)
 151       _mesa_debug(ctx, "glStencilFuncSeparateATI()\n");
 152
 153    if (!validate_stencil_func(ctx, frontfunc)) {
 154       _mesa_error(ctx, GL_INVALID_ENUM,
 155                   "glStencilFuncSeparateATI(frontfunc)");
 156       return;
 157    }
 158    if (!validate_stencil_func(ctx, backfunc)) {
 159       _mesa_error(ctx, GL_INVALID_ENUM,
 160                   "glStencilFuncSeparateATI(backfunc)");
 161       return;
 162    }
 163
 164    ref = CLAMP( ref, 0, stencilMax );
 165
 166    /* set both front and back state */
 167    if (ctx->Stencil.Function[0] == frontfunc &&
 168        ctx->Stencil.Function[1] == backfunc &&
 169        ctx->Stencil.ValueMask[0] == mask &&
 170        ctx->Stencil.ValueMask[1] == mask &&
 171        ctx->Stencil.Ref[0] == ref &&
 172        ctx->Stencil.Ref[1] == ref)
 173       return;
 174    FLUSH_VERTICES(ctx, _NEW_STENCIL);
 175    ctx->Stencil.Function[0]  = frontfunc;
 176    ctx->Stencil.Function[1]  = backfunc;
 177    ctx->Stencil.Ref[0]       = ctx->Stencil.Ref[1]       = ref;
 178    ctx->Stencil.ValueMask[0] = ctx->Stencil.ValueMask[1] = mask;
 179    if (ctx->Driver.StencilFuncSeparate) {
 180       ctx->Driver.StencilFuncSeparate(ctx, GL_FRONT,
 181                                       frontfunc, ref, mask);
 182       ctx->Driver.StencilFuncSeparate(ctx, GL_BACK,
 183                                       backfunc, ref, mask);
 184    }
 185 }
 186
 187
 188 /**
 189  * Set the function and reference value for stencil testing.
 190  *
 191  * \param func test function.
 192  * \param ref reference value.
 193  * \param mask bitmask.
 194  *
 195  * \sa glStencilFunc().
 196  *
 197  * Verifies the parameters and updates the respective values in
 198  * __struct gl_contextRec::Stencil. On change flushes the vertices and notifies the
 199  * driver via the dd_function_table::StencilFunc callback.
 200  */
 201 void GLAPIENTRY
 202 _mesa_StencilFunc( GLenum func, GLint ref, GLuint mask )
 203 {
 204    GET_CURRENT_CONTEXT(ctx);
 205    const GLint stencilMax = (1 << ctx->DrawBuffer->Visual.stencilBits) - 1;
 206    const GLint face = ctx->Stencil.ActiveFace;
 207    ASSERT_OUTSIDE_BEGIN_END(ctx);
 208
 209    if (MESA_VERBOSE & VERBOSE_API)
 210       _mesa_debug(ctx, "glStencilFunc()\n");
 211
 212    if (!validate_stencil_func(ctx, func)) {
 213       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilFunc(func)");
 214       return;
 215    }
 216
 217    ref = CLAMP( ref, 0, stencilMax );
 218
 219    if (face != 0) {
 220       if (ctx->Stencil.Function[face] == func &&
 221           ctx->Stencil.ValueMask[face] == mask &&
 222           ctx->Stencil.Ref[face] == ref)
 223          return;
 224       FLUSH_VERTICES(ctx, _NEW_STENCIL);
 225       ctx->Stencil.Function[face] = func;
 226       ctx->Stencil.Ref[face] = ref;
 227       ctx->Stencil.ValueMask[face] = mask;
 228
 229       /* Only propagate the change to the driver if EXT_stencil_two_side
 230        * is enabled.
 231        */
 232       if (ctx->Driver.StencilFuncSeparate && ctx->Stencil.TestTwoSide) {
 233          ctx->Driver.StencilFuncSeparate(ctx, GL_BACK, func, ref, mask);
 234       }
 235    }
 236    else {
 237       /* set both front and back state */
 238       if (ctx->Stencil.Function[0] == func &&
 239           ctx->Stencil.Function[1] == func &&
 240           ctx->Stencil.ValueMask[0] == mask &&
 241           ctx->Stencil.ValueMask[1] == mask &&
 242           ctx->Stencil.Ref[0] == ref &&
 243           ctx->Stencil.Ref[1] == ref)
 244          return;
 245       FLUSH_VERTICES(ctx, _NEW_STENCIL);
 246       ctx->Stencil.Function[0]  = ctx->Stencil.Function[1]  = func;
 247       ctx->Stencil.Ref[0]       = ctx->Stencil.Ref[1]       = ref;
 248       ctx->Stencil.ValueMask[0] = ctx->Stencil.ValueMask[1] = mask;
 249       if (ctx->Driver.StencilFuncSeparate) {
 250          ctx->Driver.StencilFuncSeparate(ctx,
 251                                          ((ctx->Stencil.TestTwoSide)
 252                                           ? GL_FRONT : GL_FRONT_AND_BACK),
 253                                          func, ref, mask);
 254       }
 255    }
 256 }
 257
 258
 259 /**
 260  * Set the stencil writing mask.
 261  *
 262  * \param mask bit-mask to enable/disable writing of individual bits in the
 263  * stencil planes.
 264  *
 265  * \sa glStencilMask().
 266  *
 267  * Updates gl_stencil_attrib::WriteMask. On change flushes the vertices and
 268  * notifies the driver via the dd_function_table::StencilMask callback.
 269  */
 270 void GLAPIENTRY
 271 _mesa_StencilMask( GLuint mask )
 272 {
 273    GET_CURRENT_CONTEXT(ctx);
 274    const GLint face = ctx->Stencil.ActiveFace;
 275
 276    if (MESA_VERBOSE & VERBOSE_API)
 277       _mesa_debug(ctx, "glStencilMask()\n");
 278
 279    ASSERT_OUTSIDE_BEGIN_END(ctx);
 280
 281    if (face != 0) {
 282       /* Only modify the EXT_stencil_two_side back-face state.
 283        */
 284       if (ctx->Stencil.WriteMask[face] == mask)
 285          return;
 286       FLUSH_VERTICES(ctx, _NEW_STENCIL);
 287       ctx->Stencil.WriteMask[face] = mask;
 288
 289       /* Only propagate the change to the driver if EXT_stencil_two_side
 290        * is enabled.
 291        */
 292       if (ctx->Driver.StencilMaskSeparate && ctx->Stencil.TestTwoSide) {
 293          ctx->Driver.StencilMaskSeparate(ctx, GL_BACK, mask);
 294       }
 295    }
 296    else {
 297       /* set both front and back state */
 298       if (ctx->Stencil.WriteMask[0] == mask &&
 299           ctx->Stencil.WriteMask[1] == mask)
 300          return;
 301       FLUSH_VERTICES(ctx, _NEW_STENCIL);
 302       ctx->Stencil.WriteMask[0] = ctx->Stencil.WriteMask[1] = mask;
 303       if (ctx->Driver.StencilMaskSeparate) {
 304          ctx->Driver.StencilMaskSeparate(ctx,
 305                                          ((ctx->Stencil.TestTwoSide)
 306                                           ? GL_FRONT : GL_FRONT_AND_BACK),
 307                                           mask);
 308       }
 309    }
 310 }
 311
 312
 313 /**
 314  * Set the stencil test actions.
 315  *
 316  * \param fail action to take when stencil test fails.
 317  * \param zfail action to take when stencil test passes, but depth test fails.
 318  * \param zpass action to take when stencil test passes and the depth test
 319  * passes (or depth testing is not enabled).
 320  *
 321  * \sa glStencilOp().
 322  *
 323  * Verifies the parameters and updates the respective fields in
 324  * __struct gl_contextRec::Stencil. On change flushes the vertices and notifies the
 325  * driver via the dd_function_table::StencilOp callback.
 326  */
 327 void GLAPIENTRY
 328 _mesa_StencilOp(GLenum fail, GLenum zfail, GLenum zpass)
 329 {
 330    GET_CURRENT_CONTEXT(ctx);
 331    const GLint face = ctx->Stencil.ActiveFace;
 332
 333    if (MESA_VERBOSE & VERBOSE_API)
 334       _mesa_debug(ctx, "glStencilOp()\n");
 335
 336    ASSERT_OUTSIDE_BEGIN_END(ctx);
 337
 338    if (!validate_stencil_op(ctx, fail)) {
 339       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOp(sfail)");
 340       return;
 341    }
 342    if (!validate_stencil_op(ctx, zfail)) {
 343       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOp(zfail)");
 344       return;
 345    }
 346    if (!validate_stencil_op(ctx, zpass)) {
 347       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOp(zpass)");
 348       return;
 349    }
 350
 351    if (face != 0) {
 352       /* only set active face state */
 353       if (ctx->Stencil.ZFailFunc[face] == zfail &&
 354           ctx->Stencil.ZPassFunc[face] == zpass &&
 355           ctx->Stencil.FailFunc[face] == fail)
 356          return;
 357       FLUSH_VERTICES(ctx, _NEW_STENCIL);
 358       ctx->Stencil.ZFailFunc[face] = zfail;
 359       ctx->Stencil.ZPassFunc[face] = zpass;
 360       ctx->Stencil.FailFunc[face] = fail;
 361
 362       /* Only propagate the change to the driver if EXT_stencil_two_side
 363        * is enabled.
 364        */
 365       if (ctx->Driver.StencilOpSeparate && ctx->Stencil.TestTwoSide) {
 366          ctx->Driver.StencilOpSeparate(ctx, GL_BACK, fail, zfail, zpass);
 367       }
 368    }
 369    else {
 370       /* set both front and back state */
 371       if (ctx->Stencil.ZFailFunc[0] == zfail &&
 372           ctx->Stencil.ZFailFunc[1] == zfail &&
 373           ctx->Stencil.ZPassFunc[0] == zpass &&
 374           ctx->Stencil.ZPassFunc[1] == zpass &&
 375           ctx->Stencil.FailFunc[0] == fail &&
 376           ctx->Stencil.FailFunc[1] == fail)
 377          return;
 378       FLUSH_VERTICES(ctx, _NEW_STENCIL);
 379       ctx->Stencil.ZFailFunc[0] = ctx->Stencil.ZFailFunc[1] = zfail;
 380       ctx->Stencil.ZPassFunc[0] = ctx->Stencil.ZPassFunc[1] = zpass;
 381       ctx->Stencil.FailFunc[0]  = ctx->Stencil.FailFunc[1]  = fail;
 382       if (ctx->Driver.StencilOpSeparate) {
 383          ctx->Driver.StencilOpSeparate(ctx,
 384                                        ((ctx->Stencil.TestTwoSide)
 385                                         ? GL_FRONT : GL_FRONT_AND_BACK),
 386                                        fail, zfail, zpass);
 387       }
 388    }
 389 }
 390
 391
 392
 393 #if _HAVE_FULL_GL
 394 /* GL_EXT_stencil_two_side */
 395 void GLAPIENTRY
 396 _mesa_ActiveStencilFaceEXT(GLenum face)
 397 {
 398    GET_CURRENT_CONTEXT(ctx);
 399    ASSERT_OUTSIDE_BEGIN_END(ctx);
 400
 401    if (MESA_VERBOSE & VERBOSE_API)
 402       _mesa_debug(ctx, "glActiveStencilFaceEXT()\n");
 403
 404    if (!ctx->Extensions.EXT_stencil_two_side) {
 405       _mesa_error(ctx, GL_INVALID_OPERATION, "glActiveStencilFaceEXT");
 406       return;
 407    }
 408
 409    if (face == GL_FRONT || face == GL_BACK) {
 410       FLUSH_VERTICES(ctx, _NEW_STENCIL);
 411       ctx->Stencil.ActiveFace = (face == GL_FRONT) ? 0 : 2;
 412    }
 413    else {
 414       _mesa_error(ctx, GL_INVALID_ENUM, "glActiveStencilFaceEXT(face)");
 415    }
 416 }
 417 #endif
 418
 419
 420
 421 /**
 422  * OpenGL 2.0 function.
 423  * \todo Make StencilOp() call this function.  And eventually remove the
 424  * ctx->Driver.StencilOp function and use ctx->Driver.StencilOpSeparate
 425  * instead.
 426  */
 427 void GLAPIENTRY
 428 _mesa_StencilOpSeparate(GLenum face, GLenum sfail, GLenum zfail, GLenum zpass)
 429 {
 430    GLboolean set = GL_FALSE;
 431    GET_CURRENT_CONTEXT(ctx);
 432    ASSERT_OUTSIDE_BEGIN_END(ctx);
 433
 434    if (MESA_VERBOSE & VERBOSE_API)
 435       _mesa_debug(ctx, "glStencilOpSeparate()\n");
 436
 437    if (!validate_stencil_op(ctx, sfail)) {
 438       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOpSeparate(sfail)");
 439       return;
 440    }
 441    if (!validate_stencil_op(ctx, zfail)) {
 442       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOpSeparate(zfail)");
 443       return;
 444    }
 445    if (!validate_stencil_op(ctx, zpass)) {
 446       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOpSeparate(zpass)");
 447       return;
 448    }
 449    if (face != GL_FRONT && face != GL_BACK && face != GL_FRONT_AND_BACK) {
 450       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOpSeparate(face)");
 451       return;
 452    }
 453
 454    if (face != GL_BACK) {
 455       /* set front */
 456       if (ctx->Stencil.ZFailFunc[0] != zfail ||
 457           ctx->Stencil.ZPassFunc[0] != zpass ||
 458           ctx->Stencil.FailFunc[0] != sfail){
 459          FLUSH_VERTICES(ctx, _NEW_STENCIL);
 460          ctx->Stencil.ZFailFunc[0] = zfail;
 461          ctx->Stencil.ZPassFunc[0] = zpass;
 462          ctx->Stencil.FailFunc[0] = sfail;
 463          set = GL_TRUE;
 464       }
 465    }
 466    if (face != GL_FRONT) {
 467       /* set back */
 468       if (ctx->Stencil.ZFailFunc[1] != zfail ||
 469           ctx->Stencil.ZPassFunc[1] != zpass ||
 470           ctx->Stencil.FailFunc[1] != sfail) {
 471          FLUSH_VERTICES(ctx, _NEW_STENCIL);
 472          ctx->Stencil.ZFailFunc[1] = zfail;
 473          ctx->Stencil.ZPassFunc[1] = zpass;
 474          ctx->Stencil.FailFunc[1] = sfail;
 475          set = GL_TRUE;
 476       }
 477    }
 478    if (set && ctx->Driver.StencilOpSeparate) {
 479       ctx->Driver.StencilOpSeparate(ctx, face, sfail, zfail, zpass);
 480    }
 481 }
 482
 483
 484 /* OpenGL 2.0 */
 485 void GLAPIENTRY
 486 _mesa_StencilFuncSeparate(GLenum face, GLenum func, GLint ref, GLuint mask)
 487 {
 488    GET_CURRENT_CONTEXT(ctx);
 489    const GLint stencilMax = (1 << ctx->DrawBuffer->Visual.stencilBits) - 1;
 490    ASSERT_OUTSIDE_BEGIN_END(ctx);
 491
 492    if (MESA_VERBOSE & VERBOSE_API)
 493       _mesa_debug(ctx, "glStencilFuncSeparate()\n");
 494
 495    if (face != GL_FRONT && face != GL_BACK && face != GL_FRONT_AND_BACK) {
 496       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilFuncSeparate(face)");
 497       return;
 498    }
 499    if (!validate_stencil_func(ctx, func)) {
 500       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilFuncSeparate(func)");
 501       return;
 502    }
 503
 504    ref = CLAMP(ref, 0, stencilMax);
 505
 506    FLUSH_VERTICES(ctx, _NEW_STENCIL);
 507
 508    if (face != GL_BACK) {
 509       /* set front */
 510       ctx->Stencil.Function[0] = func;
 511       ctx->Stencil.Ref[0] = ref;
 512       ctx->Stencil.ValueMask[0] = mask;
 513    }
 514    if (face != GL_FRONT) {
 515       /* set back */
 516       ctx->Stencil.Function[1] = func;
 517       ctx->Stencil.Ref[1] = ref;
 518       ctx->Stencil.ValueMask[1] = mask;
 519    }
 520    if (ctx->Driver.StencilFuncSeparate) {
 521       ctx->Driver.StencilFuncSeparate(ctx, face, func, ref, mask);
 522    }
 523 }
 524
 525
 526 /* OpenGL 2.0 */
 527 void GLAPIENTRY
 528 _mesa_StencilMaskSeparate(GLenum face, GLuint mask)
 529 {
 530    GET_CURRENT_CONTEXT(ctx);
 531    ASSERT_OUTSIDE_BEGIN_END(ctx);
 532
 533    if (MESA_VERBOSE & VERBOSE_API)
 534       _mesa_debug(ctx, "glStencilMaskSeparate()\n");
 535
 536    if (face != GL_FRONT && face != GL_BACK && face != GL_FRONT_AND_BACK) {
 537       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilaMaskSeparate(face)");
 538       return;
 539    }
 540
 541    FLUSH_VERTICES(ctx, _NEW_STENCIL);
 542
 543    if (face != GL_BACK) {
 544       ctx->Stencil.WriteMask[0] = mask;
 545    }
 546    if (face != GL_FRONT) {
 547       ctx->Stencil.WriteMask[1] = mask;
 548    }
 549    if (ctx->Driver.StencilMaskSeparate) {
 550       ctx->Driver.StencilMaskSeparate(ctx, face, mask);
 551    }
 552 }
 553
 554
 555 /**
 556  * Update derived stencil state.
 557  */
 558 void
 559 _mesa_update_stencil(struct gl_context *ctx)
 560 {
 561    const GLint face = ctx->Stencil._BackFace;
 562
 563    ctx->Stencil._Enabled = (ctx->Stencil.Enabled &&
 564                             ctx->DrawBuffer->Visual.stencilBits > 0);
 565
 566     ctx->Stencil._TestTwoSide =
 567        ctx->Stencil._Enabled &&
 568        (ctx->Stencil.Function[0] != ctx->Stencil.Function[face] ||
 569         ctx->Stencil.FailFunc[0] != ctx->Stencil.FailFunc[face] ||
 570         ctx->Stencil.ZPassFunc[0] != ctx->Stencil.ZPassFunc[face] ||
 571         ctx->Stencil.ZFailFunc[0] != ctx->Stencil.ZFailFunc[face] ||
 572         ctx->Stencil.Ref[0] != ctx->Stencil.Ref[face] ||
 573         ctx->Stencil.ValueMask[0] != ctx->Stencil.ValueMask[face] ||
 574         ctx->Stencil.WriteMask[0] != ctx->Stencil.WriteMask[face]);
 575 }
 576
 577
 578 /**
 579  * Initialize the context stipple state.
 580  *
 581  * \param ctx GL context.
 582  *
 583  * Initializes __struct gl_contextRec::Stencil attribute group.
 584  */
 585 void
 586 _mesa_init_stencil(struct gl_context *ctx)
 587 {
 588    ctx->Stencil.Enabled = GL_FALSE;
 589    ctx->Stencil.TestTwoSide = GL_FALSE;
 590    ctx->Stencil.ActiveFace = 0;  /* 0 = GL_FRONT, 2 = GL_BACK */
 591    ctx->Stencil.Function[0] = GL_ALWAYS;
 592    ctx->Stencil.Function[1] = GL_ALWAYS;
 593    ctx->Stencil.Function[2] = GL_ALWAYS;
 594    ctx->Stencil.FailFunc[0] = GL_KEEP;
 595    ctx->Stencil.FailFunc[1] = GL_KEEP;
 596    ctx->Stencil.FailFunc[2] = GL_KEEP;
 597    ctx->Stencil.ZPassFunc[0] = GL_KEEP;
 598    ctx->Stencil.ZPassFunc[1] = GL_KEEP;
 599    ctx->Stencil.ZPassFunc[2] = GL_KEEP;
 600    ctx->Stencil.ZFailFunc[0] = GL_KEEP;
 601    ctx->Stencil.ZFailFunc[1] = GL_KEEP;
 602    ctx->Stencil.ZFailFunc[2] = GL_KEEP;
 603    ctx->Stencil.Ref[0] = 0;
 604    ctx->Stencil.Ref[1] = 0;
 605    ctx->Stencil.Ref[2] = 0;
 606    ctx->Stencil.ValueMask[0] = ~0U;
 607    ctx->Stencil.ValueMask[1] = ~0U;
 608    ctx->Stencil.ValueMask[2] = ~0U;
 609    ctx->Stencil.WriteMask[0] = ~0U;
 610    ctx->Stencil.WriteMask[1] = ~0U;
 611    ctx->Stencil.WriteMask[2] = ~0U;
 612    ctx->Stencil.Clear = 0;
 613    ctx->Stencil._BackFace = 1;
 614 }