Merge pull request #4770 from samdelong/add-setHeading

Implementing p5.Vector setHeading() (Issue #4767)

Author: lmccart

src/math/p5.Vector.js

@@ -1440,6 +1440,31 @@ p5.Vector.prototype.heading = function heading() {
   return h;
 };
 
+/**
+ * Rotate the vector to a specific angle (only 2D vectors), magnitude remains the
+ * same
+ *
+ * @method setHeading
+ * @param  {number}    angle the angle of rotation
+ * @chainable
+ * @example
+ * <div class="norender">
+ * <code>
+ * let v = createVector(10.0, 20.0);
+ * // result of v.heading() is 1.1071487177940904
+ * v.setHeading(Math.PI);
+ * // result of v.heading() is now 3.141592653589793
+ * </code>
+ * </div>
+ */
+
+p5.Vector.prototype.setHeading = function setHeading(a) {
+  let m = this.mag();
+  this.x = m * Math.cos(a);
+  this.y = m * Math.sin(a);
+  return this;
+};
+
 /**
  * Rotate the vector by an angle (only 2D vectors), magnitude remains the
  * same

test/unit/math/p5.Vector.js

@@ -18,6 +18,15 @@ suite('p5.Vector', function() {
   });
   var v;
 
+  suite('setHeading', function() {
+    setup(function() {
+      v = myp5.createVector(1, 1);
+      v.setHeading(1);
+    });
+    test('should have heading() value of 1', function() {
+      assert.closeTo(v.heading(), 1, 0.001);
+    });
+  });
   suite('p5.prototype.createVector()', function() {
     setup(function() {
       v = myp5.createVector();