From 952f240eb043f626eab87dcf1348d778d96ca363 Mon Sep 17 00:00:00 2001
From: Alvin Penner <penner@vaxxine.com>
Date: Sun, 30 Aug 2015 07:37:24 -0400
Subject: lpe-powerstroke. validity check on data. (Bug 1487424)

Fixed bugs:
  - https://launchpad.net/bugs/1487424

(bzr r14333)
---
 src/live_effects/lpe-powerstroke.cpp | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

(limited to 'src')

diff --git a/src/live_effects/lpe-powerstroke.cpp b/src/live_effects/lpe-powerstroke.cpp
index f90d67d4e..03102a84a 100644
--- a/src/live_effects/lpe-powerstroke.cpp
+++ b/src/live_effects/lpe-powerstroke.cpp
@@ -102,12 +102,15 @@ static Circle touching_circle( D2<SBasis> const &curve, double t, double tol=0.0
 {
     //Piecewise<SBasis> k = curvature(curve, tol);
     D2<SBasis> dM=derivative(curve);
-    if ( are_near(L2sq(dM(t)),0.) ) {
+    if ( are_near(L2sq(dM(t)),0.) && (dM[0].size() > 1) && (dM[1].size() > 1) ) {
         dM=derivative(dM);
     }
-    if ( are_near(L2sq(dM(t)),0.) ) {   // try second time
+    if ( are_near(L2sq(dM(t)),0.) && (dM[0].size() > 1) && (dM[1].size() > 1) ) {   // try second time
         dM=derivative(dM);
     }
+    if ( are_near(L2sq(dM(t)),0.) && (dM[0].size() > 1) && (dM[1].size() > 1) ) {   // admit defeat
+        return Geom::Circle(Geom::Point(0., 0.), 0.);
+    }
     Piecewise<D2<SBasis> > unitv = unitVector(dM,tol);
     Piecewise<SBasis> dMlength = dot(Piecewise<D2<SBasis> >(dM),unitv);
     Piecewise<SBasis> k = cross(derivative(unitv),unitv);
-- 
cgit v1.2.3