enforce point and vector for origin and direction

features/src/lib.rs

@@ -7,6 +7,7 @@ pub mod color;
 pub mod canvas;
 pub mod matrix;
 pub mod transformations;
+pub mod ray;
 
 #[macro_export]
 macro_rules! num_traits_cast {

features/src/ray.rs

@@ -0,0 +1,52 @@
+use crate::structs::Tuple;
+
+#[derive(Debug, PartialEq)]
+struct Ray {
+    origin: Tuple,
+    direction: Tuple,
+}
+
+impl Ray {
+    fn new(origin: Tuple, direction: Tuple) -> Option<Ray> {
+        if !origin.is_point() || !direction.is_vector() {
+            None
+        } else {
+            Some(Ray {
+                origin,
+                direction,
+            })
+        }
+    }
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    pub fn create_a_ray() {
+        let origin = Tuple::point(1, 2, 3);
+        let direction = Tuple::vector(4, 5, 6);
+
+        let ray = Ray::new(origin, direction).unwrap();
+        assert_eq!(ray.origin, origin);
+        assert_eq!(ray.direction, direction);
+    }
+
+    #[test]
+    pub fn origin_must_be_point() {
+        let direction = Tuple::vector::<i32, i32, i32>(4, 5, 6);
+
+        let ray = Ray::new(direction, direction);
+        assert_eq!(ray, None);
+    }
+
+    #[test]
+    pub fn direction_must_be_vector() {
+        let point = Tuple::point::<i32, i32, i32>(4, 5, 6);
+        let ray = Ray::new(point, point);
+        assert_eq!(ray, None);
+    }
+
+}