From 7ee9e31e40353daa24d0a7ef325acc9878095325 Mon Sep 17 00:00:00 2001
From: Nat Lasseter <user@4574.co.uk>
Date: Wed, 3 Jul 2024 11:20:22 +0100
Subject: Refactor Hittables type

---
 hittable.go | 10 ++++------
 rtiaw.go    | 14 +++++++-------
 2 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/hittable.go b/hittable.go
index 73e2e3c..b31b205 100644
--- a/hittable.go
+++ b/hittable.go
@@ -69,18 +69,16 @@ func (s Sphere) Hit(r Ray, ray_t Interval) (rec HitRecord) {
 
 //Hittables < Hittable
 
-type Hittables struct {
-  Objects []Hittable
-}
+type Hittables []Hittable
 
-func (l *Hittables) Add(o Hittable) {
-  l.Objects = append(l.Objects, o);
+func (l Hittables) Add(o Hittable) Hittables {
+  return append(l, o);
 }
 
 func (l Hittables) Hit(r Ray, ray_t Interval) (rec HitRecord) {
   closest_so_far := ray_t.Max;
 
-  for _, o := range l.Objects {
+  for _, o := range l {
     temp_rec := o.Hit(r, Interval{ray_t.Min, closest_so_far});
     if temp_rec.Valid {
       rec = temp_rec;
diff --git a/rtiaw.go b/rtiaw.go
index 2daa826..b0d2106 100644
--- a/rtiaw.go
+++ b/rtiaw.go
@@ -13,7 +13,7 @@ func main() {
   var world Hittables;
 
   mat_ground := Lambertian{Vec3{0.5, 0.5, 0.5}};
-  world.Add(Sphere{Vec3{0, -1000, 0}, 1000, mat_ground});
+  world = world.Add(Sphere{Vec3{0, -1000, 0}, 1000, mat_ground});
 
   i := Interval{0, 1};
   for a := -11; a < 11; a++ {
@@ -29,31 +29,31 @@ func main() {
           albedo := Vec3{i.Sample(), i.Sample(), i.Sample()}.
                     Mul(Vec3{i.Sample(), i.Sample(), i.Sample()});
           mat_sphere := Lambertian{albedo};
-          world.Add(Sphere{centre, 0.2, mat_sphere});
+          world = world.Add(Sphere{centre, 0.2, mat_sphere});
         } else if (choose_mat < 0.95) {
           // metal
           j := Interval{0.5, 1};
           albedo := Vec3{j.Sample(), j.Sample(), j.Sample()};
           fuzz := j.Sample() - 0.5;
           mat_sphere := Metal{albedo, fuzz};
-          world.Add(Sphere{centre, 0.2, mat_sphere});
+          world = world.Add(Sphere{centre, 0.2, mat_sphere});
         } else {
           // glass
           mat_sphere := Dielectric{1.5};
-          world.Add(Sphere{centre, 0.2, mat_sphere});
+          world = world.Add(Sphere{centre, 0.2, mat_sphere});
         }
       }
     }
   }
 
   mat1 := Dielectric{1.5};
-  world.Add(Sphere{Vec3{0, 1, 0}, 1.0, mat1});
+  world = world.Add(Sphere{Vec3{0, 1, 0}, 1.0, mat1});
 
   mat2 := Lambertian{Vec3{0.4, 0.2, 0.1}};
-  world.Add(Sphere{Vec3{-4, 1, 0}, 1.0, mat2});
+  world = world.Add(Sphere{Vec3{-4, 1, 0}, 1.0, mat2});
 
   mat3 := Metal{Vec3{0.7, 0.6, 0.5}, 0.0};
-  world.Add(Sphere{Vec3{4, 1, 0}, 1.0, mat3});
+  world = world.Add(Sphere{Vec3{4, 1, 0}, 1.0, mat3});
 
   cam := NewCamera(1200, 16.0/9.0,
                    500, 50,
-- 
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