From 1be3f5f4de5b912bf1c5c5ed78362b1866f363e5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Viktor=20Chlumsk=C3=BD?= <viktor.chlumsky@gmail.com>
Date: Sat, 11 Feb 2017 00:20:18 +0100
Subject: [PATCH] Fixed rounding error in cubic curve splitting

---
 core/edge-segments.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/core/edge-segments.cpp b/core/edge-segments.cpp
index b9fd166..169f2bb 100644
--- a/core/edge-segments.cpp
+++ b/core/edge-segments.cpp
@@ -288,12 +288,12 @@ void QuadraticSegment::splitInThirds(EdgeSegment *&part1, EdgeSegment *&part2, E
 }
 
 void CubicSegment::splitInThirds(EdgeSegment *&part1, EdgeSegment *&part2, EdgeSegment *&part3) const {
-    part1 = new CubicSegment(p[0], mix(p[0], p[1], 1/3.), mix(mix(p[0], p[1], 1/3.), mix(p[1], p[2], 1/3.), 1/3.), point(1/3.), color);
+    part1 = new CubicSegment(p[0], p[0] == p[1] ? p[0] : mix(p[0], p[1], 1/3.), mix(mix(p[0], p[1], 1/3.), mix(p[1], p[2], 1/3.), 1/3.), point(1/3.), color);
     part2 = new CubicSegment(point(1/3.),
         mix(mix(mix(p[0], p[1], 1/3.), mix(p[1], p[2], 1/3.), 1/3.), mix(mix(p[1], p[2], 1/3.), mix(p[2], p[3], 1/3.), 1/3.), 2/3.),
         mix(mix(mix(p[0], p[1], 2/3.), mix(p[1], p[2], 2/3.), 2/3.), mix(mix(p[1], p[2], 2/3.), mix(p[2], p[3], 2/3.), 2/3.), 1/3.),
         point(2/3.), color);
-    part3 = new CubicSegment(point(2/3.), mix(mix(p[1], p[2], 2/3.), mix(p[2], p[3], 2/3.), 2/3.), mix(p[2], p[3], 2/3.), p[3], color);
+    part3 = new CubicSegment(point(2/3.), mix(mix(p[1], p[2], 2/3.), mix(p[2], p[3], 2/3.), 2/3.), p[2] == p[3] ? p[3] : mix(p[2], p[3], 2/3.), p[3], color);
 }
 
 }