X-Git-Url: https://git.libre-soc.org/?a=blobdiff_plain;f=src%2Fmesa%2Fmain%2Fstencil.c;h=93e2e97ce0c724d31cc0eaed9e2804c0c0c281d2;hb=04dca296e0a5e5ffbb8acb699e013a23ebd7b645;hp=6b4d7e81eb8b8e25f642c40eb8e8608df98c922a;hpb=22607975b49633a38ddf65127e26a30e9522d825;p=mesa.git

diff --git a/src/mesa/main/stencil.c b/src/mesa/main/stencil.c
index 6b4d7e81eb8..93e2e97ce0c 100644
--- a/src/mesa/main/stencil.c
+++ b/src/mesa/main/stencil.c
@@ -1,8 +1,8 @@
 /*
  * Mesa 3-D graphics library
- * Version:  6.5
+ * Version:  7.1
  *
- * Copyright (C) 1999-2005  Brian Paul   All Rights Reserved.
+ * Copyright (C) 1999-2007  Brian Paul   All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
@@ -27,7 +27,7 @@
  * \file stencil.c
  * Stencil operations.
  *
- * Note: There's an incompatibility between GL_EXT_stencil_two_side and
+ * Note: There's some conflict between GL_EXT_stencil_two_side and
  * OpenGL 2.0's two-sided stencil feature.
  *
  * With GL_EXT_stencil_two_side, calling glStencilOp/Func/Mask() only the
@@ -36,8 +36,14 @@
  * But with OpenGL 2.0, calling glStencilOp/Func/Mask() sets BOTH the
  * front AND back state.
  *
- * So either we advertise the GL_EXT_stencil_two_side extension, or OpenGL
- * 2.0, but not both.
+ * Also, note that GL_ATI_separate_stencil is different as well:
+ * glStencilFuncSeparateATI(GLenum frontfunc, GLenum backfunc, ...)  vs.
+ * glStencilFuncSeparate(GLenum face, GLenum func, ...).
+ *
+ * This problem is solved by keeping three sets of stencil state:
+ *  state[0] = GL_FRONT state.
+ *  state[1] = OpenGL 2.0 / GL_ATI_separate_stencil GL_BACK state.
+ *  state[2] = GL_EXT_stencil_two_side GL_BACK state.
  */
 
 
@@ -49,6 +55,48 @@
 #include "mtypes.h"
 
 
+static GLboolean
+validate_stencil_op(struct gl_context *ctx, GLenum op)
+{
+   switch (op) {
+   case GL_KEEP:
+   case GL_ZERO:
+   case GL_REPLACE:
+   case GL_INCR:
+   case GL_DECR:
+   case GL_INVERT:
+      return GL_TRUE;
+   case GL_INCR_WRAP_EXT:
+   case GL_DECR_WRAP_EXT:
+      if (ctx->Extensions.EXT_stencil_wrap) {
+         return GL_TRUE;
+      }
+      /* FALL-THROUGH */
+   default:
+      return GL_FALSE;
+   }
+}
+
+
+static GLboolean
+validate_stencil_func(struct gl_context *ctx, GLenum func)
+{
+   switch (func) {
+   case GL_NEVER:
+   case GL_LESS:
+   case GL_LEQUAL:
+   case GL_GREATER:
+   case GL_GEQUAL:
+   case GL_EQUAL:
+   case GL_NOTEQUAL:
+   case GL_ALWAYS:
+      return GL_TRUE;
+   default:
+      return GL_FALSE;
+   }
+}
+
+
 /**
  * Set the clear value for the stencil buffer.
  *
@@ -78,6 +126,62 @@ _mesa_ClearStencil( GLint s )
 }
 
 
+/**
+ * Set the function and reference value for stencil testing.
+ *
+ * \param frontfunc front test function.
+ * \param backfunc back test function.
+ * \param ref front and back reference value.
+ * \param mask front and back bitmask.
+ *
+ * \sa glStencilFunc().
+ *
+ * Verifies the parameters and updates the respective values in
+ * __struct gl_contextRec::Stencil. On change flushes the vertices and notifies the
+ * driver via the dd_function_table::StencilFunc callback.
+ */
+void GLAPIENTRY
+_mesa_StencilFuncSeparateATI( GLenum frontfunc, GLenum backfunc, GLint ref, GLuint mask )
+{
+   GET_CURRENT_CONTEXT(ctx);
+   const GLint stencilMax = (1 << ctx->DrawBuffer->Visual.stencilBits) - 1;
+   ASSERT_OUTSIDE_BEGIN_END(ctx);
+
+   if (!validate_stencil_func(ctx, frontfunc)) {
+      _mesa_error(ctx, GL_INVALID_ENUM,
+                  "glStencilFuncSeparateATI(frontfunc)");
+      return;
+   }
+   if (!validate_stencil_func(ctx, backfunc)) {
+      _mesa_error(ctx, GL_INVALID_ENUM,
+                  "glStencilFuncSeparateATI(backfunc)");
+      return;
+   }
+
+   ref = CLAMP( ref, 0, stencilMax );
+
+   /* set both front and back state */
+   if (ctx->Stencil.Function[0] == frontfunc &&
+       ctx->Stencil.Function[1] == backfunc &&
+       ctx->Stencil.ValueMask[0] == mask &&
+       ctx->Stencil.ValueMask[1] == mask &&
+       ctx->Stencil.Ref[0] == ref &&
+       ctx->Stencil.Ref[1] == ref)
+      return;
+   FLUSH_VERTICES(ctx, _NEW_STENCIL);
+   ctx->Stencil.Function[0]  = frontfunc;
+   ctx->Stencil.Function[1]  = backfunc;
+   ctx->Stencil.Ref[0]       = ctx->Stencil.Ref[1]       = ref;
+   ctx->Stencil.ValueMask[0] = ctx->Stencil.ValueMask[1] = mask;
+   if (ctx->Driver.StencilFuncSeparate) {
+      ctx->Driver.StencilFuncSeparate(ctx, GL_FRONT,
+                                      frontfunc, ref, mask);
+      ctx->Driver.StencilFuncSeparate(ctx, GL_BACK,
+                                      backfunc, ref, mask);
+   }
+}
+
+
 /**
  * Set the function and reference value for stencil testing.
  *
@@ -88,7 +192,7 @@ _mesa_ClearStencil( GLint s )
  * \sa glStencilFunc().
  *
  * Verifies the parameters and updates the respective values in
- * __GLcontextRec::Stencil. On change flushes the vertices and notifies the
+ * __struct gl_contextRec::Stencil. On change flushes the vertices and notifies the
  * driver via the dd_function_table::StencilFunc callback.
  */
 void GLAPIENTRY
@@ -96,28 +200,17 @@ _mesa_StencilFunc( GLenum func, GLint ref, GLuint mask )
 {
    GET_CURRENT_CONTEXT(ctx);
    const GLint stencilMax = (1 << ctx->DrawBuffer->Visual.stencilBits) - 1;
+   const GLint face = ctx->Stencil.ActiveFace;
    ASSERT_OUTSIDE_BEGIN_END(ctx);
 
-   switch (func) {
-      case GL_NEVER:
-      case GL_LESS:
-      case GL_LEQUAL:
-      case GL_GREATER:
-      case GL_GEQUAL:
-      case GL_EQUAL:
-      case GL_NOTEQUAL:
-      case GL_ALWAYS:
-         break;
-      default:
-         _mesa_error( ctx, GL_INVALID_ENUM, "glStencilFunc" );
-         return;
+   if (!validate_stencil_func(ctx, func)) {
+      _mesa_error(ctx, GL_INVALID_ENUM, "glStencilFunc(func)");
+      return;
    }
 
    ref = CLAMP( ref, 0, stencilMax );
 
-   if (ctx->Extensions.EXT_stencil_two_side) {
-      /* only set active face state */
-      const GLint face = ctx->Stencil.ActiveFace;
+   if (face != 0) {
       if (ctx->Stencil.Function[face] == func &&
           ctx->Stencil.ValueMask[face] == mask &&
           ctx->Stencil.Ref[face] == ref)
@@ -126,9 +219,12 @@ _mesa_StencilFunc( GLenum func, GLint ref, GLuint mask )
       ctx->Stencil.Function[face] = func;
       ctx->Stencil.Ref[face] = ref;
       ctx->Stencil.ValueMask[face] = mask;
-      if (ctx->Driver.StencilFuncSeparate) {
-         ctx->Driver.StencilFuncSeparate(ctx, face ? GL_BACK : GL_FRONT,
-                                         func, ref, mask);
+
+      /* Only propagate the change to the driver if EXT_stencil_two_side
+       * is enabled.
+       */
+      if (ctx->Driver.StencilFuncSeparate && ctx->Stencil.TestTwoSide) {
+         ctx->Driver.StencilFuncSeparate(ctx, GL_BACK, func, ref, mask);
       }
    }
    else {
@@ -145,7 +241,9 @@ _mesa_StencilFunc( GLenum func, GLint ref, GLuint mask )
       ctx->Stencil.Ref[0]       = ctx->Stencil.Ref[1]       = ref;
       ctx->Stencil.ValueMask[0] = ctx->Stencil.ValueMask[1] = mask;
       if (ctx->Driver.StencilFuncSeparate) {
-         ctx->Driver.StencilFuncSeparate(ctx, GL_FRONT_AND_BACK,
+         ctx->Driver.StencilFuncSeparate(ctx,
+					 ((ctx->Stencil.TestTwoSide)
+					  ? GL_FRONT : GL_FRONT_AND_BACK),
                                          func, ref, mask);
       }
    }
@@ -167,17 +265,23 @@ void GLAPIENTRY
 _mesa_StencilMask( GLuint mask )
 {
    GET_CURRENT_CONTEXT(ctx);
+   const GLint face = ctx->Stencil.ActiveFace;
+
    ASSERT_OUTSIDE_BEGIN_END(ctx);
 
-   if (ctx->Extensions.EXT_stencil_two_side) {
-      /* only set active face state */
-      const GLint face = ctx->Stencil.ActiveFace;
+   if (face != 0) {
+      /* Only modify the EXT_stencil_two_side back-face state.
+       */
       if (ctx->Stencil.WriteMask[face] == mask)
          return;
       FLUSH_VERTICES(ctx, _NEW_STENCIL);
       ctx->Stencil.WriteMask[face] = mask;
-      if (ctx->Driver.StencilMaskSeparate) {
-         ctx->Driver.StencilMaskSeparate(ctx, face ? GL_BACK : GL_FRONT, mask);
+
+      /* Only propagate the change to the driver if EXT_stencil_two_side
+       * is enabled.
+       */
+      if (ctx->Driver.StencilMaskSeparate && ctx->Stencil.TestTwoSide) {
+         ctx->Driver.StencilMaskSeparate(ctx, GL_BACK, mask);
       }
    }
    else {
@@ -188,7 +292,10 @@ _mesa_StencilMask( GLuint mask )
       FLUSH_VERTICES(ctx, _NEW_STENCIL);
       ctx->Stencil.WriteMask[0] = ctx->Stencil.WriteMask[1] = mask;
       if (ctx->Driver.StencilMaskSeparate) {
-         ctx->Driver.StencilMaskSeparate(ctx, GL_FRONT_AND_BACK, mask);
+         ctx->Driver.StencilMaskSeparate(ctx,
+					 ((ctx->Stencil.TestTwoSide)
+					  ? GL_FRONT : GL_FRONT_AND_BACK),
+					  mask);
       }
    }
 }
@@ -205,73 +312,32 @@ _mesa_StencilMask( GLuint mask )
  * \sa glStencilOp().
  * 
  * Verifies the parameters and updates the respective fields in
- * __GLcontextRec::Stencil. On change flushes the vertices and notifies the
+ * __struct gl_contextRec::Stencil. On change flushes the vertices and notifies the
  * driver via the dd_function_table::StencilOp callback.
  */
 void GLAPIENTRY
 _mesa_StencilOp(GLenum fail, GLenum zfail, GLenum zpass)
 {
    GET_CURRENT_CONTEXT(ctx);
+   const GLint face = ctx->Stencil.ActiveFace;
+
    ASSERT_OUTSIDE_BEGIN_END(ctx);
 
-   switch (fail) {
-      case GL_KEEP:
-      case GL_ZERO:
-      case GL_REPLACE:
-      case GL_INCR:
-      case GL_DECR:
-      case GL_INVERT:
-         break;
-      case GL_INCR_WRAP_EXT:
-      case GL_DECR_WRAP_EXT:
-         if (ctx->Extensions.EXT_stencil_wrap) {
-            break;
-         }
-         /* FALL-THROUGH */
-      default:
-         _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOp");
-         return;
+   if (!validate_stencil_op(ctx, fail)) {
+      _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOp(sfail)");
+      return;
    }
-   switch (zfail) {
-      case GL_KEEP:
-      case GL_ZERO:
-      case GL_REPLACE:
-      case GL_INCR:
-      case GL_DECR:
-      case GL_INVERT:
-         break;
-      case GL_INCR_WRAP_EXT:
-      case GL_DECR_WRAP_EXT:
-         if (ctx->Extensions.EXT_stencil_wrap) {
-            break;
-         }
-         /* FALL-THROUGH */
-      default:
-         _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOp");
-         return;
+   if (!validate_stencil_op(ctx, zfail)) {
+      _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOp(zfail)");
+      return;
    }
-   switch (zpass) {
-      case GL_KEEP:
-      case GL_ZERO:
-      case GL_REPLACE:
-      case GL_INCR:
-      case GL_DECR:
-      case GL_INVERT:
-         break;
-      case GL_INCR_WRAP_EXT:
-      case GL_DECR_WRAP_EXT:
-         if (ctx->Extensions.EXT_stencil_wrap) {
-            break;
-         }
-         /* FALL-THROUGH */
-      default:
-         _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOp");
-         return;
+   if (!validate_stencil_op(ctx, zpass)) {
+      _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOp(zpass)");
+      return;
    }
 
-   if (ctx->Extensions.EXT_stencil_two_side) {
+   if (face != 0) {
       /* only set active face state */
-      const GLint face = ctx->Stencil.ActiveFace;
       if (ctx->Stencil.ZFailFunc[face] == zfail &&
           ctx->Stencil.ZPassFunc[face] == zpass &&
           ctx->Stencil.FailFunc[face] == fail)
@@ -280,9 +346,12 @@ _mesa_StencilOp(GLenum fail, GLenum zfail, GLenum zpass)
       ctx->Stencil.ZFailFunc[face] = zfail;
       ctx->Stencil.ZPassFunc[face] = zpass;
       ctx->Stencil.FailFunc[face] = fail;
-      if (ctx->Driver.StencilOpSeparate) {
-         ctx->Driver.StencilOpSeparate(ctx, face ? GL_BACK : GL_FRONT,
-                                       fail, zfail, zpass);
+
+      /* Only propagate the change to the driver if EXT_stencil_two_side
+       * is enabled.
+       */
+      if (ctx->Driver.StencilOpSeparate && ctx->Stencil.TestTwoSide) {
+         ctx->Driver.StencilOpSeparate(ctx, GL_BACK, fail, zfail, zpass);
       }
    }
    else {
@@ -299,7 +368,9 @@ _mesa_StencilOp(GLenum fail, GLenum zfail, GLenum zpass)
       ctx->Stencil.ZPassFunc[0] = ctx->Stencil.ZPassFunc[1] = zpass;
       ctx->Stencil.FailFunc[0]  = ctx->Stencil.FailFunc[1]  = fail;
       if (ctx->Driver.StencilOpSeparate) {
-         ctx->Driver.StencilOpSeparate(ctx, GL_FRONT_AND_BACK,
+         ctx->Driver.StencilOpSeparate(ctx,
+				       ((ctx->Stencil.TestTwoSide)
+					? GL_FRONT : GL_FRONT_AND_BACK),
                                        fail, zfail, zpass);
       }
    }
@@ -322,7 +393,7 @@ _mesa_ActiveStencilFaceEXT(GLenum face)
 
    if (face == GL_FRONT || face == GL_BACK) {
       FLUSH_VERTICES(ctx, _NEW_STENCIL);
-      ctx->Stencil.ActiveFace = (face == GL_FRONT) ? 0 : 1;
+      ctx->Stencil.ActiveFace = (face == GL_FRONT) ? 0 : 2;
    }
    else {
       _mesa_error(ctx, GL_INVALID_ENUM, "glActiveStencilFaceEXT(face)");
@@ -339,86 +410,55 @@ _mesa_ActiveStencilFaceEXT(GLenum face)
  * instead.
  */
 void GLAPIENTRY
-_mesa_StencilOpSeparate(GLenum face, GLenum fail, GLenum zfail, GLenum zpass)
+_mesa_StencilOpSeparate(GLenum face, GLenum sfail, GLenum zfail, GLenum zpass)
 {
+   GLboolean set = GL_FALSE;
    GET_CURRENT_CONTEXT(ctx);
    ASSERT_OUTSIDE_BEGIN_END(ctx);
 
-   if (face != GL_FRONT && face != GL_BACK && face != GL_FRONT_AND_BACK) {
-      _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOpSeparate(face)");
+   if (!validate_stencil_op(ctx, sfail)) {
+      _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOpSeparate(sfail)");
       return;
    }
-
-   switch (fail) {
-      case GL_KEEP:
-      case GL_ZERO:
-      case GL_REPLACE:
-      case GL_INCR:
-      case GL_DECR:
-      case GL_INVERT:
-         break;
-      case GL_INCR_WRAP_EXT:
-      case GL_DECR_WRAP_EXT:
-         if (ctx->Extensions.EXT_stencil_wrap) {
-            break;
-         }
-         /* FALL-THROUGH */
-      default:
-         _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOpSeparate(fail)");
-         return;
+   if (!validate_stencil_op(ctx, zfail)) {
+      _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOpSeparate(zfail)");
+      return;
    }
-   switch (zfail) {
-      case GL_KEEP:
-      case GL_ZERO:
-      case GL_REPLACE:
-      case GL_INCR:
-      case GL_DECR:
-      case GL_INVERT:
-         break;
-      case GL_INCR_WRAP_EXT:
-      case GL_DECR_WRAP_EXT:
-         if (ctx->Extensions.EXT_stencil_wrap) {
-            break;
-         }
-         /* FALL-THROUGH */
-      default:
-         _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOpSeparate(zfail)");
-         return;
+   if (!validate_stencil_op(ctx, zpass)) {
+      _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOpSeparate(zpass)");
+      return;
    }
-   switch (zpass) {
-      case GL_KEEP:
-      case GL_ZERO:
-      case GL_REPLACE:
-      case GL_INCR:
-      case GL_DECR:
-      case GL_INVERT:
-         break;
-      case GL_INCR_WRAP_EXT:
-      case GL_DECR_WRAP_EXT:
-         if (ctx->Extensions.EXT_stencil_wrap) {
-            break;
-         }
-         /* FALL-THROUGH */
-      default:
-         _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOpSeparate(zpass)");
-         return;
+   if (face != GL_FRONT && face != GL_BACK && face != GL_FRONT_AND_BACK) {
+      _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOpSeparate(face)");
+      return;
    }
 
-   FLUSH_VERTICES(ctx, _NEW_STENCIL);
-
-   if (face == GL_FRONT || face == GL_FRONT_AND_BACK) {
-      ctx->Stencil.FailFunc[0] = fail;
-      ctx->Stencil.ZFailFunc[0] = zfail;
-      ctx->Stencil.ZPassFunc[0] = zpass;
+   if (face != GL_BACK) {
+      /* set front */
+      if (ctx->Stencil.ZFailFunc[0] != zfail ||
+          ctx->Stencil.ZPassFunc[0] != zpass ||
+          ctx->Stencil.FailFunc[0] != sfail){
+         FLUSH_VERTICES(ctx, _NEW_STENCIL);
+         ctx->Stencil.ZFailFunc[0] = zfail;
+         ctx->Stencil.ZPassFunc[0] = zpass;
+         ctx->Stencil.FailFunc[0] = sfail;
+         set = GL_TRUE;
+      }
    }
-   if (face == GL_BACK || face == GL_FRONT_AND_BACK) {
-      ctx->Stencil.FailFunc[1] = fail;
-      ctx->Stencil.ZFailFunc[1] = zfail;
-      ctx->Stencil.ZPassFunc[1] = zpass;
+   if (face != GL_FRONT) {
+      /* set back */
+      if (ctx->Stencil.ZFailFunc[1] != zfail ||
+          ctx->Stencil.ZPassFunc[1] != zpass ||
+          ctx->Stencil.FailFunc[1] != sfail) {
+         FLUSH_VERTICES(ctx, _NEW_STENCIL);
+         ctx->Stencil.ZFailFunc[1] = zfail;
+         ctx->Stencil.ZPassFunc[1] = zpass;
+         ctx->Stencil.FailFunc[1] = sfail;
+         set = GL_TRUE;
+      }
    }
-
-   if (ctx->Driver.StencilOpSeparate) {
-      ctx->Driver.StencilOpSeparate(ctx, face, fail, zfail, zpass);
+   if (set && ctx->Driver.StencilOpSeparate) {
+      ctx->Driver.StencilOpSeparate(ctx, face, sfail, zfail, zpass);
    }
 }
 
@@ -435,37 +475,27 @@ _mesa_StencilFuncSeparate(GLenum face, GLenum func, GLint ref, GLuint mask)
       _mesa_error(ctx, GL_INVALID_ENUM, "glStencilFuncSeparate(face)");
       return;
    }
-
-   switch (func) {
-      case GL_NEVER:
-      case GL_LESS:
-      case GL_LEQUAL:
-      case GL_GREATER:
-      case GL_GEQUAL:
-      case GL_EQUAL:
-      case GL_NOTEQUAL:
-      case GL_ALWAYS:
-         break;
-      default:
-         _mesa_error(ctx, GL_INVALID_ENUM, "glStencilFuncSeparate(func)");
-         return;
+   if (!validate_stencil_func(ctx, func)) {
+      _mesa_error(ctx, GL_INVALID_ENUM, "glStencilFuncSeparate(func)");
+      return;
    }
 
    ref = CLAMP(ref, 0, stencilMax);
 
    FLUSH_VERTICES(ctx, _NEW_STENCIL);
 
-   if (face == GL_FRONT || face == GL_FRONT_AND_BACK) {
+   if (face != GL_BACK) {
+      /* set front */
       ctx->Stencil.Function[0] = func;
       ctx->Stencil.Ref[0] = ref;
       ctx->Stencil.ValueMask[0] = mask;
    }
-   if (face == GL_BACK || face == GL_FRONT_AND_BACK) {
+   if (face != GL_FRONT) {
+      /* set back */
       ctx->Stencil.Function[1] = func;
       ctx->Stencil.Ref[1] = ref;
       ctx->Stencil.ValueMask[1] = mask;
    }
-
    if (ctx->Driver.StencilFuncSeparate) {
       ctx->Driver.StencilFuncSeparate(ctx, face, func, ref, mask);
    }
@@ -486,13 +516,12 @@ _mesa_StencilMaskSeparate(GLenum face, GLuint mask)
 
    FLUSH_VERTICES(ctx, _NEW_STENCIL);
 
-   if (face == GL_FRONT || face == GL_FRONT_AND_BACK) {
+   if (face != GL_BACK) {
       ctx->Stencil.WriteMask[0] = mask;
    }
-   if (face == GL_BACK || face == GL_FRONT_AND_BACK) {
+   if (face != GL_FRONT) {
       ctx->Stencil.WriteMask[1] = mask;
    }
-
    if (ctx->Driver.StencilMaskSeparate) {
       ctx->Driver.StencilMaskSeparate(ctx, face, mask);
    }
@@ -503,21 +532,22 @@ _mesa_StencilMaskSeparate(GLenum face, GLuint mask)
  * Update derived stencil state.
  */
 void
-_mesa_update_stencil(GLcontext *ctx)
+_mesa_update_stencil(struct gl_context *ctx)
 {
-   if (ctx->Extensions.EXT_stencil_two_side) {
-      ctx->Stencil._TestTwoSide = ctx->Stencil.TestTwoSide;
-   }
-   else {
-      ctx->Stencil._TestTwoSide = 
-         (ctx->Stencil.Function[0] != ctx->Stencil.Function[1] ||
-          ctx->Stencil.FailFunc[0] != ctx->Stencil.FailFunc[1] ||
-          ctx->Stencil.ZPassFunc[0] != ctx->Stencil.ZPassFunc[1] ||
-          ctx->Stencil.ZFailFunc[0] != ctx->Stencil.ZFailFunc[1] ||
-          ctx->Stencil.Ref[0] != ctx->Stencil.Ref[1] ||
-          ctx->Stencil.ValueMask[0] != ctx->Stencil.ValueMask[1] ||
-          ctx->Stencil.WriteMask[0] != ctx->Stencil.WriteMask[1]);
-   }
+   const GLint face = ctx->Stencil._BackFace;
+
+   ctx->Stencil._Enabled = (ctx->Stencil.Enabled &&
+                            ctx->DrawBuffer->Visual.stencilBits > 0);
+
+    ctx->Stencil._TestTwoSide =
+       ctx->Stencil._Enabled &&
+       (ctx->Stencil.Function[0] != ctx->Stencil.Function[face] ||
+	ctx->Stencil.FailFunc[0] != ctx->Stencil.FailFunc[face] ||
+	ctx->Stencil.ZPassFunc[0] != ctx->Stencil.ZPassFunc[face] ||
+	ctx->Stencil.ZFailFunc[0] != ctx->Stencil.ZFailFunc[face] ||
+	ctx->Stencil.Ref[0] != ctx->Stencil.Ref[face] ||
+	ctx->Stencil.ValueMask[0] != ctx->Stencil.ValueMask[face] ||
+	ctx->Stencil.WriteMask[0] != ctx->Stencil.WriteMask[face]);
 }
 
 
@@ -526,27 +556,35 @@ _mesa_update_stencil(GLcontext *ctx)
  *
  * \param ctx GL context.
  *
- * Initializes __GLcontextRec::Stencil attribute group.
+ * Initializes __struct gl_contextRec::Stencil attribute group.
  */
 void
-_mesa_init_stencil(GLcontext *ctx)
+_mesa_init_stencil(struct gl_context *ctx)
 {
    ctx->Stencil.Enabled = GL_FALSE;
    ctx->Stencil.TestTwoSide = GL_FALSE;
-   ctx->Stencil.ActiveFace = 0;  /* 0 = GL_FRONT, 1 = GL_BACK */
+   ctx->Stencil.ActiveFace = 0;  /* 0 = GL_FRONT, 2 = GL_BACK */
    ctx->Stencil.Function[0] = GL_ALWAYS;
    ctx->Stencil.Function[1] = GL_ALWAYS;
+   ctx->Stencil.Function[2] = GL_ALWAYS;
    ctx->Stencil.FailFunc[0] = GL_KEEP;
    ctx->Stencil.FailFunc[1] = GL_KEEP;
+   ctx->Stencil.FailFunc[2] = GL_KEEP;
    ctx->Stencil.ZPassFunc[0] = GL_KEEP;
    ctx->Stencil.ZPassFunc[1] = GL_KEEP;
+   ctx->Stencil.ZPassFunc[2] = GL_KEEP;
    ctx->Stencil.ZFailFunc[0] = GL_KEEP;
    ctx->Stencil.ZFailFunc[1] = GL_KEEP;
+   ctx->Stencil.ZFailFunc[2] = GL_KEEP;
    ctx->Stencil.Ref[0] = 0;
    ctx->Stencil.Ref[1] = 0;
+   ctx->Stencil.Ref[2] = 0;
    ctx->Stencil.ValueMask[0] = ~0U;
    ctx->Stencil.ValueMask[1] = ~0U;
+   ctx->Stencil.ValueMask[2] = ~0U;
    ctx->Stencil.WriteMask[0] = ~0U;
    ctx->Stencil.WriteMask[1] = ~0U;
+   ctx->Stencil.WriteMask[2] = ~0U;
    ctx->Stencil.Clear = 0;
+   ctx->Stencil._BackFace = 1;
 }