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