Add simple ray module.

rtiow/src/lib.rs

@@ -1 +1,2 @@
+pub mod ray;
 pub mod vec3;

rtiow/src/ray.rs

@@ -0,0 +1,22 @@
+use vec3::Vec3;
+
+#[derive(Default)]
+pub struct Ray {
+    a: Vec3,
+    b: Vec3,
+}
+
+impl Ray {
+    pub fn new(a: Vec3, b: Vec3) -> Ray {
+        Ray { a, b }
+    }
+    pub fn origin(self) -> Vec3 {
+        self.a
+    }
+    pub fn direction(self) -> Vec3 {
+        self.b
+    }
+    pub fn point_at_parameter(self, t: f32) -> Vec3 {
+        self.a + self.b * t
+    }
+}