Fix vetor.normalizeLength to due what the description says. As I coul…

…d only find the bug due to my own application, I also added tests for that case.

lib/src/vector_math/vector2.dart

@@ -148,13 +148,13 @@ class Vector2 implements Vector {
 
   /// Normalize [this]. Returns length of vector before normalization.
   double normalizeLength() {
-    var l = length;
+    final l = length;
     if (l == 0.0) {
       return 0.0;
     }
-    l = 1.0 / l;
-    _storage2[0] *= l;
-    _storage2[1] *= l;
+    final d = 1.0 / l;
+    _storage2[0] *= d;
+    _storage2[1] *= d;
     return l;
   }
 
@@ -200,7 +200,7 @@ class Vector2 implements Vector {
     return _storage2[0] * otherStorage[1] - _storage2[1] * otherStorage[0];
   }
 
-  /// Rotate [this] by 90 degrees then scale it. Store result in [out]. Return 
+  /// Rotate [this] by 90 degrees then scale it. Store result in [out]. Return
   /// [out].
   Vector2 scaleOrthogonalInto(double scale, Vector2 out) {
     out.setValues(-scale * _storage2[1], scale * _storage2[0]);

lib/src/vector_math/vector3.dart

@@ -51,7 +51,7 @@ class Vector3 implements Vector {
   Float32List get storage => _storage3;
 
   /// Construct a new vector with the specified values.
-  factory Vector3(double x, double y, double z) => 
+  factory Vector3(double x, double y, double z) =>
       new Vector3.zero()..setValues(x, y, z);
 
   /// Initialized with values from [array] starting at [offset].
@@ -158,14 +158,14 @@ class Vector3 implements Vector {
 
   /// Normalize [this]. Returns length of vector before normalization.
   double normalizeLength() {
-    var l = length;
+    final l = length;
     if (l == 0.0) {
       return 0.0;
     }
-    l = 1.0 / l;
-    _storage3[0] *= l;
-    _storage3[1] *= l;
-    _storage3[2] *= l;
+    final d = 1.0 / l;
+    _storage3[0] *= d;
+    _storage3[1] *= d;
+    _storage3[2] *= d;
     return l;
   }
 

lib/src/vector_math/vector4.dart

@@ -179,15 +179,15 @@ class Vector4 implements Vector {
 
   /// Normalizes [this]. Returns length of vector before normalization.
   double normalizeLength() {
-    var l = length;
+    final l = length;
     if (l == 0.0) {
       return 0.0;
     }
-    l = 1.0 / l;
-    _storage4[0] *= l;
-    _storage4[1] *= l;
-    _storage4[2] *= l;
-    _storage4[3] *= l;
+    final d = 1.0 / l;
+    _storage4[0] *= d;
+    _storage4[1] *= d;
+    _storage4[2] *= d;
+    _storage4[3] *= d;
     return l;
   }
 
@@ -196,7 +196,6 @@ class Vector4 implements Vector {
 
   /// Normalize vector into [out].
   Vector4 normalizeInto(Vector4 out) {
-    //TODO (fox32): Remove this method?
     out.setFrom(this);
     return out..normalize();
   }

test/test_vector.dart

@@ -73,6 +73,42 @@ class VectorTest extends BaseTest {
     expect(b.w, equals(8.0));
   }
 
+  void testVec2Length() {
+    final Vector2 a = new Vector2(5.0, 7.0);
+
+    relativeTest(a.length, 8.6);
+    relativeTest(a.length2, 74.0);
+
+    relativeTest(a.normalizeLength(), 8.6);
+    relativeTest(a.x, 0.5812);
+    relativeTest(a.y, 0.8137);
+  }
+
+  void testVec3Length() {
+    final Vector3 a = new Vector3(5.0, 7.0, 3.0);
+
+    relativeTest(a.length, 9.1104);
+    relativeTest(a.length2, 83.0);
+
+    relativeTest(a.normalizeLength(), 9.1104);
+    relativeTest(a.x, 0.5488);
+    relativeTest(a.y, 0.7683);
+    relativeTest(a.z, 0.3292);
+  }
+
+  void testVec4Length() {
+    final Vector4 a = new Vector4(5.0, 7.0, 3.0, 10.0);
+
+    relativeTest(a.length, 13.5277);
+    relativeTest(a.length2, 183.0);
+
+    relativeTest(a.normalizeLength(), 13.5277);
+    relativeTest(a.x, 0.3696);
+    relativeTest(a.y, 0.5174);
+    relativeTest(a.z, 0.2217);
+    relativeTest(a.w, 0.7392);
+  }
+
   void testVec2MinMax() {
     final Vector2 a = new Vector2(5.0, 7.0);
     final Vector2 b = new Vector2(3.0, 8.0);
@@ -628,6 +664,10 @@ class VectorTest extends BaseTest {
     test('3D add', testVec3Add);
     test('4D add', testVec4Add);
 
+    test('2D length', testVec2Length);
+    test('3D length', testVec3Length);
+    test('4D length', testVec4Length);
+
     test('2D min/max', testVec2MinMax);
     test('3D min/max', testVec3MinMax);
     test('4D min/max', testVec4MinMax);