commit 24e4bdd4158909e9720422208ab0a0aca788e700
author Mikko Mononen <memononen@gmail.com> Wed Jan 14 10:41:03 2015 +0200
committer Mikko Mononen <memononen@gmail.com> Wed Jan 14 10:41:03 2015 +0200
tree ccc954d0d62784976d2141f6d642ac720fbd4ded
parent 041a3ae2778fadaee2bdef3b4a962aae7d0f4f88
parent d7c34ac3ff11993b0fc0395fe7d96f4cc75e6bb6

Merge pull request #10 from openscad/sentinel-workaround

Sentinel workaround, should fix #8

Source/sweep.c

diff --git a/Source/sweep.c b/Source/sweep.c
index 73da935..112f1ef 100755
--- a/Source/sweep.c
+++ b/Source/sweep.c
@@ -1121,10 +1121,12 @@
 	w = (tess->bmax[0] - tess->bmin[0]);
 	h = (tess->bmax[1] - tess->bmin[1]);
 
-	smin = tess->bmin[0] - w;
-	smax = tess->bmax[0] + w;
-	tmin = tess->bmin[1] - h;
-	tmax = tess->bmax[1] + h;
+        /* If the bbox is empty, ensure that sentinels are not coincident by
+           slightly enlarging it. */
+	smin = tess->bmin[0] - (w > 0 ? w : 0.01);
+        smax = tess->bmax[0] + (w > 0 ? w : 0.01);
+        tmin = tess->bmin[1] - (h > 0 ? h : 0.01);
+        tmax = tess->bmax[1] + (h > 0 ? h : 0.01);
 
 	AddSentinel( tess, smin, smax, tmin );
 	AddSentinel( tess, smin, smax, tmax );