From 4d159518071045b960f186c8dea1ce5c6f3cc5e1 Mon Sep 17 00:00:00 2001
From: Werner Almesberger <werner@almesberger.net>
Date: Fri, 16 Jan 2015 08:30:17 -0300
Subject: [PATCH] cameo/area-poly2d.c (area): fail if any paths are open

---
 cameo/area-poly2d.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/cameo/area-poly2d.c b/cameo/area-poly2d.c
index 7d506b5..643f6de 100644
--- a/cameo/area-poly2d.c
+++ b/cameo/area-poly2d.c
@@ -1,8 +1,8 @@
 /*
  * area-poly2d.c - Area fill (using libpoly2d)
  *
- * Written 2012 by Werner Almesberger
- * Copyright 2012 Werner Almesberger
+ * Written 2012, 2015 by Werner Almesberger
+ * Copyright 2012, 2015 Werner Almesberger
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -10,6 +10,8 @@
  * (at your option) any later version.
  */
 
+#include <stdlib.h>
+#include <stdio.h>
 #include <math.h>
 
 #include "poly2d.h"
@@ -47,7 +49,16 @@ struct path *area(const struct path *paths, double overlap)
 	double z = HUGE_VAL, best_z;
 	const struct path *path;
 	struct path *res = NULL, **last = &res;
+	unsigned n = 0, bad = 0;
 
+	for (path = paths; path; path = path->next) {
+		bad += !path_is_closed(path);
+		n++;
+	}
+	if (bad) {
+		fprintf(stderr, "%u/%u open paths\n", bad, n);
+		exit(1);
+	}
 	while (1) {
 		best_z = -HUGE_VAL;
 		for (path = paths; path; path = path->next) {