From bd3bbdd239fd91056442384bfe3a86b2b8c0e68e Mon Sep 17 00:00:00 2001
From: Nat Lasseter <user@4574.co.uk>
Date: Mon, 24 Jun 2024 17:26:09 +0100
Subject: chapter 9

---
 ray.go | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

(limited to 'ray.go')

diff --git a/ray.go b/ray.go
index cd4f6aa..18c8a39 100644
--- a/ray.go
+++ b/ray.go
@@ -10,17 +10,22 @@ type Ray struct {
 }
 
 func (r Ray) At(t float64) Vec3 {
-  return r.Origin.Add(r.Direction.Mul(Splat(t)));
+  return r.Origin.Add(r.Direction.Mul(SplatVec3(t)));
 }
 
-func (r Ray) Colour(world Hittable) Vec3 {
-  hit := world.Hit(r, Interval{0, maths.Inf(1)})
+func (r Ray) Colour(world Hittable, md uint) Vec3 {
+  if md <= 0 {
+    return SplatVec3(0);
+  }
+
+  hit := world.Hit(r, Interval{0.001, maths.Inf(1)})
   if hit.Valid {
-    return hit.N.Add(Splat(1)).Div(Splat(2));
+    dir := hit.N.Add(RandomVec3OnUnitSphere());
+    return Ray{hit.P, dir}.Colour(world, md - 1).Div(SplatVec3(10));
   }
 
   unit_dir := r.Direction.Unit();
   a := (unit_dir.Y + 1) / 2;
-  return Vec3{0.5, 0.7, 1.0}.Mul(Splat(a)).
-         Add(Splat(1).Mul(Splat(1.0 - a)));
+  return Vec3{0.5, 0.7, 1.0}.Mul(SplatVec3(a)).
+         Add(SplatVec3(1).Mul(SplatVec3(1.0 - a)));
 }
-- 
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