Translate and scale a ray

ray-tracer/src/types/ray.rs

@@ -1,7 +1,6 @@
+use crate::types::{Matrix, Point, Sphere, Vector};
 use std::cmp::Ordering;
 
-use crate::types::{Point, Sphere, Vector};
-
 #[derive(Clone, Debug, PartialEq)]
 pub struct Intersection<'a> {
     t: f64,
@@ -65,13 +64,22 @@ impl Ray {
         vec![
             Intersection { t: t1, object: &s },
             Intersection { t: t2, object: &s },
-        ].into()
+        ]
+        .into()
+    }
+
+    pub fn transform(&self, m: Matrix) -> Self {
+        Self {
+            origin: m.clone() * self.origin,
+            direction: m * self.direction, 
+        }
     }
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::transforms::{scaling, translation};
 
     #[test]
     fn computing_point_from_distance() {
@@ -173,4 +181,22 @@ mod tests {
 
         assert_eq!(xs.hit(), Some(&i4));
     }
+
+    #[test]
+    fn translate_a_ray() {
+        let r = Ray::new(Point::new(1., 2., 3.), Vector::new(0., 1., 0.));
+        let m = translation(3., 4., 5.);
+        let r2 = r.transform(m);
+        assert_eq!(r2.origin, Point::new(4., 6., 8.));
+        assert_eq!(r2.direction, Vector::new(0., 1., 0.));
+    }
+
+    #[test]
+    fn scale_a_ray() {
+        let r = Ray::new(Point::new(1., 2., 3.), Vector::new(0., 1., 0.));
+        let m = scaling(2., 3., 4.);
+        let r2 = r.transform(m);
+        assert_eq!(r2.origin, Point::new(2., 6., 12.));
+        assert_eq!(r2.direction, Vector::new(0., 3., 0.,));
+    }
 }