Use objects instead of array to represent points in Bezier-Curve

Author: felipernb

src/algorithms/geometry/bezier_curve.js

@@ -3,57 +3,55 @@
 /**
  * 2D bezier-curve, https://en.wikipedia.org/wiki/B%C3%A9zier_curve
  * Usage:
- *   var b = new BezierCurve([ [0, 0], [10, 3] ]);
- *   b.get(0.5); // [5, 1.5]
+ *   var b = new BezierCurve([{x: 0, y: 0}, {x: 10, y: 3}]);
+ *   b.get(0.5); // {x: 5, y: 1.5}
  */
 
 /**
  * Generates a bezier-curve from a series of points
- * @param Array array of control points ([[x0, y0], [x1, y1]])
+ * @param Array array of control points ([{x: x0, y: y0}, {x: x1, y: y1}])
  */
-var BezierCurve = function (array) {
-    var n = array.length;
-
-    // The binomial coefficient
-    var c = [1];
-    var i, j;
-    for (i = 1; i < n; ++i) {
-        c.push(0);
-        for (j = i; j >= 1; --j) {
-            c[j] += c[j - 1];
-        }
+var BezierCurve = function (points) {
+  this.n = points.length;
+  this.p = [];
+
+  // The binomial coefficient
+  var c = [1];
+  var i, j;
+  for (i = 1; i < this.n; ++i) {
+    c.push(0);
+    for (j = i; j >= 1; --j) {
+        c[j] += c[j - 1];
     }
+  }
 
-    // the i-th control point times the coefficient
-    var p = [];
-    for (i = 0; i < n; ++i) {
-        p.push([c[i] * array[i][0], c[i] * array[i][1]]);
-    }
-
-    this.p = p;
-    this.n = n;
+  // the i-th control point times the coefficient
+  for (i = 0; i < this.n; ++i) {
+    this.p.push({x: c[i] * points[i].x, y: c[i] * points[i].y});
+  }
 };
 
 /**
  * @param Number float variable from 0 to 1
  */
 BezierCurve.prototype.get = function (t) {
-    var res = [0, 0], i;
-    var a = 1, b = 1;
-
-    // The coefficient
-    var c = [];
-    for (i = 0; i < this.n; ++i) {
-        c.push(a);
-        a *= t;
-    }
-
-    for (i = this.n - 1; i >= 0; --i) {
-        res[0] += this.p[i][0] * c[i] * b;
-        res[1] += this.p[i][1] * c[i] * b;
-        b *= 1 - t;
-    }
-    return res;
+  var res = {x: 0, y: 0};
+  var i;
+  var a = 1, b = 1;
+
+  // The coefficient
+  var c = [];
+  for (i = 0; i < this.n; ++i) {
+    c.push(a);
+    a *= t;
+  }
+
+  for (i = this.n - 1; i >= 0; --i) {
+    res.x += this.p[i].x * c[i] * b;
+    res.y += this.p[i].y * c[i] * b;
+    b *= 1 - t;
+  }
+  return res;
 };
 
 module.exports = BezierCurve;

src/test/algorithms/geometry/bezier_curve.js

@@ -7,29 +7,34 @@ var root = require('../../../'),
 // Testing with http://pomax.github.io/bezierjs/
 
 describe('Bézier-Curve Algorithm', function () {
-    it('should get a linear Bézier-curve', function () {
-        var b = new BezierCurve([[0, 0], [10, 3]]);
-
-        // Ends
-        assert.deepEqual(b.get(0), [0, 0]);
-        assert.deepEqual(b.get(1), [10, 3]);
-
-        // Middle
-        assert.deepEqual(b.get(0.5), [5, 1.5]);
-
-        // 1/4 and 3/4
-        assert.deepEqual(b.get(0.25), [2.5, 0.75]);
-        assert.deepEqual(b.get(0.75), [7.5, 2.25]);
-    });
-    it('should get a quadratic Bézier-curve', function () {
-        var b = new BezierCurve([[150, 40], [80, 30], [105, 150]]);
-
-        assert.deepEqual(b.get(0.5), [103.75, 62.5]);
-        assert.deepEqual(b.get(0.25), [120.9375, 43.125]);
-    });
-    it('should get a cubic Bézier-curve', function () {
-        var b = new BezierCurve([[150, 40], [80, 30], [105, 150], [100, 100]]);
-
-        assert.deepEqual(b.get(0.5), [100.625, 85]);
-    });
+  it('should get a linear Bézier-curve', function () {
+    var b = new BezierCurve([{x: 0, y: 0}, {x: 10, y: 3}]);
+
+    // Ends
+    assert.deepEqual(b.get(0), {x: 0, y: 0});
+    assert.deepEqual(b.get(1), {x: 10, y: 3});
+
+    // Middle
+    assert.deepEqual(b.get(0.5), {x: 5, y: 1.5});
+
+    // 1/4 and 3/4
+    assert.deepEqual(b.get(0.25), {x: 2.5, y: 0.75});
+    assert.deepEqual(b.get(0.75), {x: 7.5, y: 2.25});
+  });
+  it('should get a quadratic Bézier-curve', function () {
+    var b = new BezierCurve([{x: 150, y: 40},
+                             {x: 80, y: 30},
+                             {x: 105, y: 150}]);
+
+    assert.deepEqual(b.get(0.5), {x: 103.75, y: 62.5});
+    assert.deepEqual(b.get(0.25), {x: 120.9375, y: 43.125});
+  });
+  it('should get a cubic Bézier-curve', function () {
+    var b = new BezierCurve([{x: 150, y: 40},
+                             {x: 80, y: 30},
+                             {x: 105, y: 150},
+                             {x: 100, y: 100}]);
+
+    assert.deepEqual(b.get(0.5), {x: 100.625, y: 85});
+  });
 });