From 54e19d4d5f6a9282ff0b9d975b248dc3f2a339bf Mon Sep 17 00:00:00 2001
From: Thilo Behnke <thilo.behnke@gmx.net>
Date: Thu, 21 Apr 2022 20:16:44 +0200
Subject: [PATCH] better mutate vector instead of cloning and normalizing

---
 pong/src/geom.rs           | 14 ++++++--------
 pong/tests/vector_tests.rs | 12 ++++++------
 2 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/pong/src/geom.rs b/pong/src/geom.rs
index 5b29678..d624376 100644
--- a/pong/src/geom.rs
+++ b/pong/src/geom.rs
@@ -28,16 +28,14 @@ pub mod geom {
             self.y /= length;
         }
 
-        pub fn perpendicular_clockwise(&self) -> Vector {
-            let mut vector = Vector::new(self.y, -self.x);
-            vector.normalize();
-            vector
+        pub fn perpendicular_clockwise(&mut self) {
+            self.x = self.y;
+            self.y = -self.x;
         }
 
-        pub fn perpendicular_counter_clockwise(&self) -> Vector {
-            let mut vector = Vector::new(-self.y, self.x);
-            vector.normalize();
-            vector
+        pub fn perpendicular_counter_clockwise(&mut self) {
+            self.x = -self.y;
+            self.y = self.x;
         }
 
         pub fn add(&mut self, other: &Vector) {
diff --git a/pong/tests/vector_tests.rs b/pong/tests/vector_tests.rs
index fb8944a..c359166 100644
--- a/pong/tests/vector_tests.rs
+++ b/pong/tests/vector_tests.rs
@@ -47,11 +47,11 @@ pub fn should_calculate_angle_correctly(
 #[case(Vector::new(0., 1.), Vector::new(1., 0.))]
 #[case(Vector::new(7., 7.), Vector::new(0.7071067811865476, -0.7071067811865476))]
 pub fn should_get_perpendicular_clockwise(
-    #[case] vector: Vector,
+    #[case] mut vector: Vector,
     #[case] expected: Vector
 ) {
-    let res = vector.perpendicular_clockwise();
-    assert_eq!(res, expected);
+    vector.perpendicular_clockwise();
+    assert_eq!(vector, expected);
 }
 
 #[rstest]
@@ -59,9 +59,9 @@ pub fn should_get_perpendicular_clockwise(
 #[case(Vector::new(1., 0.), Vector::new(0., 1.))]
 #[case(Vector::new(7., 7.), Vector::new(-0.7071067811865476, 0.7071067811865476))]
 pub fn should_get_perpendicular_counter_clockwise(
-    #[case] vector: Vector,
+    #[case] mut vector: Vector,
     #[case] expected: Vector
 ) {
-    let res = vector.perpendicular_counter_clockwise();
-    assert_eq!(res, expected);
+    vector.perpendicular_counter_clockwise();
+    assert_eq!(vector, expected);
 }