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authorBrian Paul <[email protected]>2009-02-19 14:36:58 -0700
committerIan Romanick <[email protected]>2009-03-13 17:38:36 -0700
commit66eea4e1045476b6e6602470bd813a7ee37aada7 (patch)
treef775321a8ef674b61677c10098ccbcffc779e722 /src/mesa/main/stencil.c
parente428cf3afd464b1b823ba63ff815635ad282d2ae (diff)
mesa: fix/update/restore comments related to two-sided stencil (cherry picked from commit a304cc6cca2ee21c3b25041abf882ef0616e5244)
Diffstat (limited to 'src/mesa/main/stencil.c')
-rw-r--r--src/mesa/main/stencil.c19
1 files changed, 18 insertions, 1 deletions
diff --git a/src/mesa/main/stencil.c b/src/mesa/main/stencil.c
index 6d6bbb2286b..e4a255d0a7e 100644
--- a/src/mesa/main/stencil.c
+++ b/src/mesa/main/stencil.c
@@ -27,6 +27,23 @@
* \file stencil.c
* Stencil operations.
*
+ * 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
+ * front OR back face state (as set by glActiveStencilFaceEXT) is set.
+ *
+ * But with OpenGL 2.0, calling glStencilOp/Func/Mask() sets BOTH the
+ * front AND back state.
+ *
+ * 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.
*/
@@ -542,7 +559,7 @@ _mesa_init_stencil(GLcontext *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;