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authorPeter Clifton <pcjc2@cam.ac.uk>2010-11-24 15:24:31 +0000
committerBrian Paul <brianp@vmware.com>2010-11-24 12:14:54 -0700
commitee88727df8b133e99608e5d30cbd50fb6e11628a (patch)
tree8a05d306a234af18bb9cf0894185b29107f3e25d /src/mesa/drivers/common
parent03a4f97a68dc0bf7008efcfdb61fd7033357d1ab (diff)
meta: Mask Stencil.Clear against stencilMax in _mesa_meta_Clear
This fixes incorrect behaviour when the stencil clear value exceeds the size of the stencil buffer, for example, when set with: glClearStencil (~1); /* Set a bit pattern of 111...11111110 */ glClear (GL_STENCIL_BUFFER_BIT); The clear value needs to be masked by the value 2^m - 1, where m is the number of bits in the stencil buffer. Previously, we passed the value masked with 0x7fffffff to _mesa_StencilFuncSeparate which then clamps, NOT masks the value to the range 0 to 2^m - 1. The result would be clearing the stencil buffer to 0xff, rather than 0xfe. Signed-off-by: Peter Clifton <pcjc2@cam.ac.uk> Signed-off-by: Brian Paul <brianp@vmware.com>
Diffstat (limited to 'src/mesa/drivers/common')
-rw-r--r--src/mesa/drivers/common/meta.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/src/mesa/drivers/common/meta.c b/src/mesa/drivers/common/meta.c
index ba8be12571..95accc1813 100644
--- a/src/mesa/drivers/common/meta.c
+++ b/src/mesa/drivers/common/meta.c
@@ -1398,6 +1398,7 @@ _mesa_meta_Clear(struct gl_context *ctx, GLbitfield buffers)
struct vertex verts[4];
/* save all state but scissor, pixel pack/unpack */
GLbitfield metaSave = META_ALL - META_SCISSOR - META_PIXEL_STORE;
+ const GLuint stencilMax = (1 << ctx->DrawBuffer->Visual.stencilBits) - 1;
if (buffers & BUFFER_BITS_COLOR) {
/* if clearing color buffers, don't save/restore colormask */
@@ -1453,7 +1454,7 @@ _mesa_meta_Clear(struct gl_context *ctx, GLbitfield buffers)
_mesa_StencilOpSeparate(GL_FRONT_AND_BACK,
GL_REPLACE, GL_REPLACE, GL_REPLACE);
_mesa_StencilFuncSeparate(GL_FRONT_AND_BACK, GL_ALWAYS,
- ctx->Stencil.Clear & 0x7fffffff,
+ ctx->Stencil.Clear & stencilMax,
ctx->Stencil.WriteMask[0]);
}
else {