Add magnitude() and normalize() methods to Tuple

rtchallenge/src/tuples.rs

@@ -15,6 +15,19 @@ impl Tuple {
     fn is_vector(&self) -> bool {
         self.w == 0.0
     }
+
+    fn magnitude(&self) -> f32 {
+        (self.x * self.x + self.y * self.y + self.z * self.z + self.w * self.w).sqrt()
+    }
+    fn normalize(&self) -> Tuple {
+        let m = self.magnitude();
+        Tuple {
+            x: self.x / m,
+            y: self.y / m,
+            z: self.z / m,
+            w: self.w / m,
+        }
+    }
 }
 
 impl Add for Tuple {
@@ -102,6 +115,8 @@ fn tuple(x: f32, y: f32, z: f32, w: f32) -> Tuple {
 
 #[cfg(test)]
 mod tests {
+    use float_cmp::approx_eq;
+
     use super::{point, tuple, vector};
     #[test]
     fn is_point() {
@@ -185,4 +200,29 @@ mod tests {
         let a = tuple(1., -2., 3., -4.);
         assert_eq!(a / 2., tuple(0.5, -1., 1.5, -2.));
     }
+    #[test]
+    fn vector_magnitude() {
+        assert_eq!(1., vector(1., 0., 0.).magnitude());
+        assert_eq!(1., vector(0., 1., 0.).magnitude());
+        assert_eq!(1., vector(0., 0., 1.).magnitude());
+        assert_eq!(14_f32.sqrt(), vector(1., 2., 3.).magnitude());
+        assert_eq!(14_f32.sqrt(), vector(-1., -2., -3.).magnitude());
+    }
+    #[test]
+    fn vector_normalize() {
+        assert_eq!(vector(1., 0., 0.), vector(4., 0., 0.).normalize());
+        assert_eq!(
+            vector(1. / 14_f32.sqrt(), 2. / 14_f32.sqrt(), 3. / 14_f32.sqrt()),
+            vector(1., 2., 3.).normalize()
+        );
+    }
+    #[test]
+    fn vector_normalize_magnitude() {
+        assert!(approx_eq!(
+            f32,
+            1.,
+            vector(1., 2., 3.).normalize().magnitude(),
+            ulps = 1
+        ));
+    }
 }