Don't mutate the vector during calculation of euclidian distance

Author: ad-si

index.coffee

@@ -1,3 +1,5 @@
+calculateLength = (x, y, z) -> Math.sqrt (x * x) + (y * y) + (z * z)
+
 class Vector
 	constructor: (@x = 0, @y = 0, @z = 0) ->
 		@isNormalized = undefined
@@ -56,11 +58,14 @@ class Vector
 
 		return @
 
-	length: () ->
-		return Math.sqrt (@x * @x) + (@y * @y) + (@z * @z)
+	length: () -> calculateLength @x, @y, @z
 
 	euclideanDistanceTo: (vector) ->
-		return @subtract(vector).length()
+		return calculateLength(
+			@x - vector.x
+			@y - vector.y
+			@z - vector.z
+		)
 
 	normalize: () ->
 		@isNormalized = true

test/main.coffee

@@ -75,9 +75,11 @@ runTest 'Returns a vector\'s length', (test) ->
 
 runTest 'Returns the euclidian distance to a vector', (test) ->
 	vectorA = new Vector(4, 2, 0)
+	vectorAReference = vectorA.clone()
 	vectorB = new Vector(3, 5, 7)
 	expectedDistance = 7.681145747868608
 	test.same(vectorA.euclideanDistanceTo(vectorB), expectedDistance)
+	test.same(vectorA, vectorAReference)
 
 
 runTest 'Normalizes a vector', (test) ->