Mesa (lp-binning): llvmpipe: tweak subpixel_snap() arithmetic

[Brian Paul]

Module: Mesa
Branch: lp-binning
Commit: 212f3a6cb3cb49127a6e5588553fe2d327f46563
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=212f3a6cb3cb49127a6e5588553fe2d327f46563

Author: Brian Paul <brianp at vmware.com>
Date:   Wed Jan 13 09:29:43 2010 -0700

llvmpipe: tweak subpixel_snap() arithmetic

This adjustment fixes some rasterization differences between llvmpipe
and softpipe (and other renderers).

---

 src/gallium/drivers/llvmpipe/lp_setup_tri.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/src/gallium/drivers/llvmpipe/lp_setup_tri.c b/src/gallium/drivers/llvmpipe/lp_setup_tri.c
index 9248125..575265b 100644
--- a/src/gallium/drivers/llvmpipe/lp_setup_tri.c
+++ b/src/gallium/drivers/llvmpipe/lp_setup_tri.c
@@ -237,7 +237,7 @@ static void setup_tri_coefficients( struct setup_context *setup,
 
 static inline int subpixel_snap( float a )
 {
-   return util_iround(FIXED_ONE * a);
+   return util_iround(FIXED_ONE * a - (FIXED_ONE / 2));
 }