Slight tweak to how ray offsets are done.

src/math/point.rs

@@ -89,6 +89,14 @@ impl Sub for Point {
     }
 }
 
+impl Sub<Vector> for Point {
+    type Output = Point;
+
+    fn sub(self, other: Vector) -> Point {
+        Point { co: self.co - other.co }
+    }
+}
+
 impl Mul<Matrix4x4> for Point {
     type Output = Point;
 

src/renderer.rs

@@ -268,8 +268,8 @@ impl LightPath {
                         let la = dot(rnor, shadow_vec.normalized()).max(0.0);
                         self.light_attenuation = XYZ::from_spectral_sample(&XYZ::new(la, la, la)
                             .to_spectral_sample(self.wavelength));
-                        *ray = Ray::new(pos + shadow_vec.normalized() * 0.0001,
-                                        shadow_vec,
+                        *ray = Ray::new(pos + rnor * 0.0001,
+                                        shadow_vec - rnor * 0.0001,
                                         self.time,
                                         true);