Test chained transformations

ray-tracer/src/transforms.rs

@@ -189,4 +189,31 @@ mod tests {
         let p = Point::new(2., 3., 4.);
         assert_eq!(transform * p, Point::new(2., 3., 7.));
     }
+
+    #[test]
+    fn individual_transformations_are_applied_in_sequence() {
+        let p = Point::new(1., 0., 1.);
+        let rotation = rotation_x(PI / 2.);
+        let scale = scaling(5., 5., 5.);
+        let translate = translation(10., 5., 7.);
+
+        let p2 = rotation * p;
+        assert_eq!(p2, Point::new(1., -1., 0.));
+
+        let p3 = scale * p2;
+        assert_eq!(p3, Point::new(5., -5., 0.));
+
+        let p4 = translate * p3;
+        assert_eq!(p4, Point::new(15., 0., 7.));
+    }
+
+    #[test]
+    fn chained_translations() {
+        let p = Point::new(1., 0., 1.);
+        let rotation = rotation_x(PI / 2.);
+        let scale = scaling(5., 5., 5.);
+        let translate = translation(10., 5., 7.);
+        let tr = translate * scale * rotation;
+        assert_eq!(tr * p, Point::new(15., 0., 7.));
+    }
 }