From: Eric Anholt <eric@anholt.net>
Date: Fri, 19 Dec 2008 02:23:51 +0000 (-0800)
Subject: mesa: Correct _mesa_clip_to_region() off-by-one.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=aa09e0a1d532d0de2e094957d0509a7f60ebeafa;p=mesa.git

mesa: Correct _mesa_clip_to_region() off-by-one.

Note how if:
x + width == xmax + 0: width -= 0
x + width == xmax + 1: width -= 0
x + width == xmax + 2: width -= 1

So, the function was clipping to [xmin, xmax+1), not [xmin, xmax) like it was
supposed to.  Same for ymax.
---

diff --git a/src/mesa/main/image.c b/src/mesa/main/image.c
index 4551b4a3b5b..6b19fc8454c 100644
--- a/src/mesa/main/image.c
+++ b/src/mesa/main/image.c
@@ -5152,7 +5152,7 @@ _mesa_clip_to_region(GLint xmin, GLint ymin,
 
    /* right clipping */
    if (*x + *width > xmax)
-      *width -= (*x + *width - xmax - 1);
+      *width -= (*x + *width - xmax);
 
    if (*width <= 0)
       return GL_FALSE;
@@ -5165,7 +5165,7 @@ _mesa_clip_to_region(GLint xmin, GLint ymin,
 
    /* top (or bottom) clipping */
    if (*y + *height > ymax)
-      *height -= (*y + *height - ymax - 1);
+      *height -= (*y + *height - ymax);
 
    if (*height <= 0)
       return GL_FALSE;