nit test for bezier

README.md

@@ -17,7 +17,42 @@ var curve = new jsspline.BSpline({
 for(var i = 0; i < 100; ++i) {
  curve.addWayPoint({ x: i, y: Math.sin(Math.PI * i * 0.2), z: 0.0});
 }
-console.log("nodes: " + curve.nodes.length);
+console.log("nodes: " + curve.nodes.length); // 9700 interpolated points
+
+// first node
+curve.nodes[0].x;
+curve.nodes[0].y;
+curve.nodes[0].z;
+
+// second node
+curve.nodes[1].x;
+curve.nodes[1].y;
+curve.nodes[1].z;
+// distance from the first node
+curve.distances[1]
+
+// third node
+curve.nodes[2].x;
+curve.nodes[2].y;
+curve.nodes[2].z;
+// distance from the first node
+curve.distances[2]
+```
+
+### Bezier
+
+The sample code below create a Bezier curve which create 4900 nodes (i.e., interpolated points) from 100 way points
+
+```javascript
+var jsspline = require("js-spline");
+
+var curve = new jsspline.Bezier({
+    steps: 100 // number of interpolated points between 4 way points
+});
+for(var i = 0; i < 100; ++i) {
+ curve.addWayPoint({ x: i, y: Math.sin(Math.PI * i * 0.2), z: 0.0});
+}
+console.log("nodes: " + curve.nodes.length); // 4900 interpolated points
 
 // first node
 curve.nodes[0].x;

src/jsspline.js

@@ -102,7 +102,7 @@ var jsspline = jsspline || {};
                 } else {
                     k = j - 2;
                     pt4 = this.way_points[k].scale(2).minus(this.way_points[k-1]);
-                    node = this.interpolate(u, this.way_points[pt], pt4, this.way_points[pt+1], this.way_points[pt+2]);
+                    node = this.interpolate(u, this.way_points[k], pt4, this.way_points[k+1], this.way_points[k+2]);
                 }
                 var distance = 0;
                 if(this.nodes.length > 0){
@@ -114,7 +114,7 @@ var jsspline = jsspline || {};
         }
     };
 
-    Bezier.interpolate = function(u, pt1, pt2, pt3, pt4){
+    Bezier.prototype.interpolate = function(u, pt1, pt2, pt3, pt4){
         var point = pt1.scale(-1).add(pt2.scale(3)).minus(pt3.scale(3)).add(pt4).scale(u*u*u);
         point = point.add(pt1.scale(3).minus(pt2.scale(6)).add(pt3.scale(3)).scale(u*u));
         point = point.add(pt1.scale(-3).add(pt2.scale(3)).scale(u));

test/bezier-spec.js

@@ -0,0 +1,16 @@
+var expect    = require("chai").expect;
+var jsspline = require("../src/jsspline");
+
+describe("Bezier", function() {
+  it("should create a interpolated Bezier curve", function(){
+      var curve = new jsspline.Bezier({
+          steps: 100
+      });
+      for(var i = 0; i < 100; ++i) {
+         curve.addWayPoint({ x: i, y: Math.sin(Math.PI * i * 0.2), z: 0.0});
+      }
+      console.log("nodes: " + curve.nodes.length);
+      expect(curve.nodes.length).to.equal(4900);
+  });
+
+});