From ee88727df8b133e99608e5d30cbd50fb6e11628a Mon Sep 17 00:00:00 2001 From: Peter Clifton Date: Wed, 24 Nov 2010 15:24:31 +0000 Subject: [PATCH] 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 Signed-off-by: Brian Paul --- src/mesa/drivers/common/meta.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/src/mesa/drivers/common/meta.c b/src/mesa/drivers/common/meta.c index ba8be125718..95accc1813d 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 { -- 2.30.2