Fixes incorrect up clear operation for large glClearStencil() values.
--
Peter Clifton
Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,
Cambridge
CB3 0FA
Tel: +44 (0)7729 980173 - (No signal in the lab!)
Tel: +44 (0)1223 748328 - (Shared lab phone, ask for me)
>From 0ac4370d1d0e53439a29b845d7e49c9368cbe1f1 Mon Sep 17 00:00:00 2001
From: Peter Clifton <pc...@cam.ac.uk>
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 <pc...@cam.ac.uk>
---
src/mesa/drivers/common/meta.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/src/mesa/drivers/common/meta.c b/src/mesa/drivers/common/meta.c
index ba8be12..40227ba 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 GLstencil 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 {
--
1.7.1
------------------------------------------------------------------------------
Increase Visibility of Your 3D Game App & Earn a Chance To Win $500!
Tap into the largest installed PC base & get more eyes on your game by
optimizing for Intel(R) Graphics Technology. Get started today with the
Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs.
http://p.sf.net/sfu/intelisp-dev2dev
_______________________________________________
Mesa3d-dev mailing list
Mesa3d-dev@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/mesa3d-dev
