vec2.normalize

bpl · May 2, 2012 · 30b4242 · 30b4242
1 parent 9981a83
commit 30b4242
Showing 2 changed files with 36 additions and 0 deletions.
diff --git a/gl-matrix.js b/gl-matrix.js
@@ -2399,6 +2399,27 @@
         return dest;
     };
 
+    /**
+     * Normlize a vec2
+     *
+     * @param {vec2} vec vec2 to normalize
+     * @param {vec2} [dest] vec2 receiving operation result. If not specified result is written to vec
+     *
+     * @returns {vec2} dest if specified, vec otherwise
+     */
+    vec2.normalize = function (vec, dest) {
+        if (!dest) { dest = vec; }
+        var mag = vec[0] * vec[0] + vec[1] * vec[1];
+        if (mag > 0) {
+          mag = Math.sqrt(mag);
+          dest[0] = vec[0] / mag;
+          dest[1] = vec[1] / mag;
+        } else {
+          dest[0] = dest[1] = 0;
+        }
+        return dest;
+    };
+
     /*
      * Exports
      */

diff --git a/spec/javascripts/vec2_spec.js b/spec/javascripts/vec2_spec.js
@@ -13,6 +13,21 @@ describe("vec2", function() {
     });
   });
 
+  describe("normalize", function() {
+    describe("with dest given", function() {
+      beforeEach(function() { result = vec2.normalize(vecA, dest); });
+      it("should store normal in dest", function() { expect(dest).toBeEqualish([ 0.4472135954999579, 0.8944271909999159 ]); });
+      it("should return dest", function() { expect(result).toBe(dest); });
+      it("should not alter vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
+    });
+
+    describe("with dest not given", function() {
+      beforeEach(function() { result = vec2.normalize(vecA); });
+      it("should store normal in vecA", function() { expect(vecA).toBeEqualish([ 0.4472135954999579, 0.8944271909999159 ]); });
+      it("should return vecA", function() { expect(result).toBe(vecA); });
+    });
+  });
+
   describe("negate", function() {
     describe("with dest given", function() {
       beforeEach(function() { result = vec2.negate(vecA, dest); });