Prevent NaN results when previous, point, and next are all the same

diff --git a/src/core/core.helpers.js b/src/core/core.helpers.js
index 1f19a5c0a8d435057041d5a10901442ea769a1dc..50d5c51ecb02d93adcc7b1368724d3cfaf9bb4a6 100644 (file)
--- a/src/core/core.helpers.js
+++ b/src/core/core.helpers.js
@@ -321,27 +321,29 @@
                aliasPixel = helpers.aliasPixel = function(pixelWidth) {
                        return (pixelWidth % 2 === 0) ? 0 : 0.5;
                },
-               splineCurve = helpers.splineCurve = function(FirstPoint, MiddlePoint, AfterPoint, t) {
+               splineCurve = helpers.splineCurve = function(firstPoint, middlePoint, afterPoint, t) {
                        //Props to Rob Spencer at scaled innovation for his post on splining between points
                        //http://scaledinnovation.com/analytics/splines/aboutSplines.html
 
                        // This function must also respect "skipped" points
 
-                       var previous = FirstPoint,
-                               current = MiddlePoint,
-                               next = AfterPoint;
+                       var previous = firstPoint.skip ? middlePoint : firstPoint,
+                               current = middlePoint,
+                               next = afterPoint.skip ? middlePoint : afterPoint;
 
-                       if (previous.skip) {
-                               previous = current;
-                       }
-                       if (next.skip) {
-                               next = current;
-                       }
+                       var d01 = Math.sqrt(Math.pow(current.x - previous.x, 2) + Math.pow(current.y - previous.y, 2));
+                       var d12 = Math.sqrt(Math.pow(next.x - current.x, 2) + Math.pow(next.y - current.y, 2));
+                       
+                       var s01 = d01 / (d01 + d12);
+                       var s12 = d12 / (d01 + d12);
+
+                       // If all points are the same, s01 & s02 will be inf
+                       s01 = isNaN(s01) ? 0 : s01;
+                       s12 = isNaN(s12) ? 0 : s12;
+
+                       var fa = t * s01; // scaling factor for triangle Ta
+                       var fb = t * s12;
 
-                       var d01 = Math.sqrt(Math.pow(current.x - previous.x, 2) + Math.pow(current.y - previous.y, 2)),
-                               d12 = Math.sqrt(Math.pow(next.x - current.x, 2) + Math.pow(next.y - current.y, 2)),
-                               fa = t * d01 / (d01 + d12), // scaling factor for triangle Ta
-                               fb = t * d12 / (d01 + d12);
                        return {
                                previous: {
                                        x: current.x - fa * (next.x - previous.x),