From 8c1324c0742ec92e62805d877c61b8886d52e553 Mon Sep 17 00:00:00 2001
From: David <Phireh@hotmail.com>
Date: Sat, 21 Aug 2021 00:20:51 +0200
Subject: [PATCH] Midway hittable list inclusion

---
 Makefile          |  2 +-
 hittable.cpp      | 16 ++++++++++++++
 hittable.hpp      | 25 ++++++++++++++++++++++
 hittable_list.hpp | 45 ++++++++++++++++++++++++++++++++++++++++
 sphere.hpp        | 53 +++++++++++++++++++++++++++++++++++++++++++++++
 vec3.hpp          |  2 +-
 6 files changed, 141 insertions(+), 2 deletions(-)
 create mode 100644 hittable.cpp
 create mode 100644 hittable.hpp
 create mode 100644 hittable_list.hpp
 create mode 100644 sphere.hpp

diff --git a/Makefile b/Makefile
index a88ac5c..5f8bbab 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-raytracer: main.cpp vec3.hpp color.hpp ray.hpp
+raytracer: main.cpp vec3.hpp color.hpp ray.hpp hittable.hpp sphere.hpp hittable_list.hpp
 	@g++ -g -Wall -Wextra -Wpedantic main.cpp -o raytracer
 
 image: raytracer
diff --git a/hittable.cpp b/hittable.cpp
new file mode 100644
index 0000000..c3b21d4
--- /dev/null
+++ b/hittable.cpp
@@ -0,0 +1,16 @@
+#ifndef HITTABLE_H
+#define HITTABLE_H
+
+#include "ray.h"
+
+struct hit_record {
+    point3 p;
+    vec3 normal;
+    double t;
+};
+
+struct hittable {
+    virtual bool hit(const ray& r, double t_min, double t_max, hit_record& rec) const = 0;
+};
+
+#endif
diff --git a/hittable.hpp b/hittable.hpp
new file mode 100644
index 0000000..42cc05e
--- /dev/null
+++ b/hittable.hpp
@@ -0,0 +1,25 @@
+#ifndef HITTABLE_H
+#define HITTABLE_H
+
+#include "ray.hpp"
+
+/* Representation of a hitpoint of a ray against a hittable object */
+struct hit_record {
+    point3 p;
+    vec3 normal;
+    double t;
+    bool front_face;
+
+    inline void set_face_normal(const ray& r, const vec3& outward_normal)
+    {
+        front_face = dot(r.direction, outward_normal) < 0;
+        normal = front_face ? outward_normal : -outward_normal;
+    }    
+};
+
+/* Virtual class that represents objects who could collide against a ray */
+struct hittable {
+    virtual bool hit(const ray& r, double t_min, double t_max, hit_record& rec) const = 0;
+};
+
+#endif
diff --git a/hittable_list.hpp b/hittable_list.hpp
new file mode 100644
index 0000000..2a5c609
--- /dev/null
+++ b/hittable_list.hpp
@@ -0,0 +1,45 @@
+#ifndef HITTABLE_LIST_H
+#define HITTABLE_LIST_H
+
+#include "hittable.hpp"
+
+#include <memory>
+#include <vector>
+
+using std::shared_ptr;
+using std::make_shared;
+
+struct hittable_list : hittable {
+    /* Attributes */
+    std::vector<shared_ptr<hittable>> objects;
+
+    /* Constructor */
+    hittable_list(shared_ptr<hittable> h) { add(h); }
+
+    /* Methods */
+    void clear() { objects.clear(); }
+    void add (shared_ptr<hittable> h) { objects.push_back(h); }
+
+    virtual bool hit(const ray& r, double t_min, double t_max, hit_record& rec) const override;
+};
+
+bool hittable_list::hit(const ray& r, double t_min, double t_max, hit_record& rec) const
+{
+    hit_record temp_rec;
+    bool hit_anything = false;
+    double closest_so_far = t_max;
+
+    for (const auto& object : objects)
+    {
+        if (object->hit(r, t_min, closest_so_far, temp_rec))
+        {
+            hit_anything = true;
+            closest_so_far = temp_rec.t;
+            rec = temp_rec;
+        }
+    }
+
+    return hit_anything;
+}
+
+#endif
diff --git a/sphere.hpp b/sphere.hpp
new file mode 100644
index 0000000..f92d2ce
--- /dev/null
+++ b/sphere.hpp
@@ -0,0 +1,53 @@
+#ifndef SPHERE_H
+#define SPHERE_H
+
+#include "hittable.hpp"
+#include "vec3.hpp"
+
+struct sphere : hittable {
+    /* Attributes */
+    point3 center;
+    double radius;
+
+    /* Contructor */
+    sphere(point3 c, double r)
+    {
+        center = c;
+        radius = r;
+    }
+
+    /* Virtual methods declaration */
+    virtual bool hit(const ray& r, double t_min, double t_max, hit_record& rec) const override;
+};
+
+/* Virtual method implementations */
+bool sphere::hit(const ray& r, double t_min, double t_max, hit_record& rec) const
+{
+    vec3 oc = r.origin - center;
+    double a = r.direction.length_squared();
+    double half_b = dot(oc, r.direction);
+    double c = oc.length_squared() - radius*radius;
+
+    double discriminant = half_b*half_b - a*c;
+    if (discriminant < 0)
+        return false;
+    double sqrtd = sqrt(discriminant);
+
+    // Find the nearest root that lies in the acceptable range
+    double root = (-half_b - sqrtd) / a;
+    if (root < t_min || t_max < root)
+    {
+        root = (-half_b + sqrtd) / a;
+        if (root < t_min || t_max < root)
+            return false;       
+    }
+
+    rec.t = root;
+    rec.p = r.at(rec.t);
+    vec3 outward_normal = (rec.p - center) / radius;
+    rec.set_face_normal(r, outward_normal);
+
+    return true;
+}
+
+#endif
diff --git a/vec3.hpp b/vec3.hpp
index a841b0d..fbb44f0 100644
--- a/vec3.hpp
+++ b/vec3.hpp
@@ -21,7 +21,7 @@ struct vec3 {
     /* Overriden operators */
 
     // - operator. Not to be confused with substraction
-    vec3 operator-()
+    vec3 operator-() const
     {
         return vec3(-x, -y, -z);
     }