chap 9.3

1 files changed, 6 insertions, 3 deletions

diff --git a/lib/ray.rb b/lib/ray.rb
index 47f2b26..c1679a5 100644
--- a/lib/ray.rb
+++ b/lib/ray.rb
@@ -10,9 +10,12 @@ class Ray
     @origin + (@direction * time)
   end
 
-  def colour(world)
-    if rec = world.hit(self, Interval.new(0, Float::INFINITY))
-      return (Colour.new(1,1,1) + rec.normal) * 0.5
+  def colour(world, depth)
+    return Colour.new if depth <= 0
+
+    if rec = world.hit(self, Interval.new(0.0001, Float::INFINITY))
+      dir = Vec3.random_unit(rec.normal)
+      return Ray.new(rec.point, dir).colour(world, depth - 1) * 0.5
     end
 
     unit_dir = direction.unit