Adding basic materials (lambertian and metallic).

.gitignore

@@ -1,3 +1,3 @@
 *.o
 wtracer
-image.ppm
+*.ppm

Makefile

@@ -1,9 +1,9 @@
 CXX = g++
 
-CXXFLAGS  = -std=c++14 -Wall -Wextra -march=native -Ofast -fopenmp -flto
+CXXFLAGS  = -std=c++14 -Wall -Wextra -Wno-unused-parameter -march=native -Ofast -fopenmp -flto
 
-DEPS = util.h vec3.h color.h ray.h camera.h hittable.h hittable_list.h sphere.h
-OBJ = wtracer.o
+DEPS = util.h vec3.h color.h ray.h camera.h hittable.h hittable_list.h sphere.h material.h
+OBJ = wtracer.o material.o vec3.o
 
 TARGET = wtracer
 

hittable.h

@@ -1,11 +1,17 @@
 #ifndef HITTABLE_H
 #define HITTABLE_H
 
+#include <memory>
+
 #include "ray.h"
+#include "material.h"
+
+class Material;
 
 struct hit_record {
   Point3 p;
   Vec3 normal;
+  std::shared_ptr<Material> mat_ptr;
   double t;
   bool front_face;
 

material.cpp

@@ -0,0 +1,17 @@
+#include "material.h"
+
+bool Lambertian::scatter(const Ray& r_in, const hit_record& rec, Color& attenuation, Ray& scattered) const {
+  //Vec3 scatter_direction = rec.normal + random_in_unit_sphere();
+  Vec3 scatter_direction = rec.normal + random_unit_vector();
+  //Vec3 scatter_direction = random_in_hemisphere(rec.normal);
+  scattered = Ray(rec.p, scatter_direction);
+  attenuation = albedo;
+  return true;
+}
+
+bool Metal::scatter(const Ray& r_in, const hit_record& rec, Color& attenuation, Ray& scattered) const {
+  Vec3 reflected = reflect(unit_vector(r_in.direction()), rec.normal);
+  scattered = Ray(rec.p, reflected);
+  attenuation = albedo;
+  return (dot(scattered.direction(), rec.normal) > 0);
+}

material.h

@@ -0,0 +1,33 @@
+#ifndef MATERIAL_H
+#define MATERIAL_H
+
+#include "hittable.h"
+#include "vec3.h"
+
+struct hit_record;
+
+class Material {
+public:
+  virtual bool scatter(const Ray& r_in, const hit_record& rec, Color& attenuation, Ray& scattered) const = 0;
+};
+
+class Lambertian : public Material {
+public:
+  Lambertian(const Color& a) : albedo(a) {}
+
+  virtual bool scatter(const Ray& r_in, const hit_record& rec, Color& attenuation, Ray& scattered) const;
+
+private:
+  Color albedo;
+};
+
+class Metal : public Material {
+public:
+  Metal(const Color& a) : albedo(a) {}
+
+  virtual bool scatter(const Ray& r_in, const hit_record& rec, Color& attenuation, Ray& scattered) const;
+private:
+  Color albedo;
+};
+
+#endif // MATERIAL_H

sphere.h

@@ -2,20 +2,23 @@
 #define SPHERE_H
 
 #include <cmath>
+#include <memory>
 
 #include "hittable.h"
+#include "material.h"
 #include "vec3.h"
 
 class Sphere : public Hittable {
 public:
   Sphere() {}
-  Sphere(Point3 cen, double r) : center(cen), radius(r) {}
+  Sphere(Point3 cen, double r, std::shared_ptr<Material> m) : center(cen), radius(r), mat_ptr(m) {}
 
   virtual bool hit(const Ray& r, double tmin, double tmax, hit_record& rec) const;
 
 private:
   Point3 center;
   double radius;
+  std::shared_ptr<Material> mat_ptr;
 };
 
 bool Sphere::hit(const Ray& r, double tmin, double tmax, hit_record& rec) const {
@@ -32,6 +35,7 @@ bool Sphere::hit(const Ray& r, double tmin, double tmax, hit_record& rec) const
             rec.p = r.at(rec.t);
             Vec3 outward_normal = (rec.p - center) / radius;
             rec.set_face_normal(r, outward_normal);
+            rec.mat_ptr = mat_ptr;
             return true;
         }
         temp = (-half_b + root) / a;
@@ -40,6 +44,7 @@ bool Sphere::hit(const Ray& r, double tmin, double tmax, hit_record& rec) const
             rec.p = r.at(rec.t);
             Vec3 outward_normal = (rec.p - center) / radius;
             rec.set_face_normal(r, outward_normal);
+            rec.mat_ptr = mat_ptr;
             return true;
         }
     }

vec3.cpp

@@ -0,0 +1,24 @@
+#include "vec3.h"
+
+Vec3 random_in_unit_sphere() {
+    while (true) {
+        auto p = Vec3::random(-1, 1);
+        if (p.length_squared() >= 1) continue;
+        return p;
+    }
+}
+
+Vec3 random_unit_vector() {
+    auto a = random_double(0, 2*pi);
+    auto z = random_double(-1, 1);
+    auto r = std::sqrt(1 - z*z);
+    return Vec3(r*std::cos(a), r*std::sin(a), z);
+}
+
+Vec3 random_in_hemisphere(const Vec3& normal) {
+    Vec3 in_unit_sphere = random_in_unit_sphere();
+    if (dot(in_unit_sphere, normal) > 0.0)
+        return in_unit_sphere;
+    else
+        return -in_unit_sphere;
+}

vec3.h

@@ -112,27 +112,14 @@ inline Vec3 unit_vector(Vec3 v) {
     return v / v.length();
 }
 
-Vec3 random_in_unit_sphere() {
-    while (true) {
-        auto p = Vec3::random(-1, 1);
-        if (p.length_squared() >= 1) continue;
-        return p;
-    }
+inline Vec3 reflect(const Vec3& v, const Vec3& n) {
+    return v - 2 * dot(v, n) * n;
 }
 
-Vec3 random_unit_vector() {
-    auto a = random_double(0, 2*pi);
-    auto z = random_double(-1, 1);
-    auto r = std::sqrt(1 - z*z);
-    return Vec3(r*std::cos(a), r*std::sin(a), z);
-}
+Vec3 random_in_unit_sphere();
 
-Vec3 random_in_hemisphere(const Vec3& normal) {
-    Vec3 in_unit_sphere = random_in_unit_sphere();
-    if (dot(in_unit_sphere, normal) > 0.0)
-        return in_unit_sphere;
-    else
-        return -in_unit_sphere;
-}
+Vec3 random_unit_vector();
+
+Vec3 random_in_hemisphere(const Vec3& normal);
 
 #endif  // VEC3_H

wtracer.cpp

@@ -17,10 +17,11 @@ Color ray_color(const Ray& r, const Hittable& world, int depth) {
         return Color(0, 0, 0);
 
     if (world.hit(r, 0.001, infinity, rec)) {
-        //Point3 target = rec.p + rec.normal + random_in_unit_sphere();
-        //Point3 target = rec.p + rec.normal + random_unit_vector();
-        Point3 target = rec.p + random_in_hemisphere(rec.normal);
-        return 0.5 * ray_color(Ray(rec.p, target - rec.p), world, depth-1);
+        Ray scattered;
+        Color attenuation;
+        if (rec.mat_ptr->scatter(r, rec, attenuation, scattered))
+          return attenuation * ray_color(scattered, world, depth - 1);
+        return Color(0, 0, 0);
     }
     Vec3 unit_direction = unit_vector(r.direction());
     auto t = 0.5 * (unit_direction.y() + 1.0);
@@ -33,14 +34,21 @@ int main() {
     const int image_width = 768;
     //const int image_width = 384;
     const int image_height = static_cast<int>(image_width / aspect_ratio);
+    //const int samples_per_pixel = 1000;
     const int samples_per_pixel = 400;
     const int max_depth = 50;
 
     std::cout << "P3\n" << image_width << " " << image_height << "\n255\n";
 
     Hittable_list world;
-    world.add(std::make_shared<Sphere>(Point3(0, 0, -1), 0.5));
-    world.add(std::make_shared<Sphere>(Point3(0, -100.5, -1), 100));
+    /*world.add(std::make_shared<Sphere>(Point3(0, 0, -1), 0.5));
+    world.add(std::make_shared<Sphere>(Point3(0, -100.5, -1), 100));*/
+
+    world.add(std::make_shared<Sphere>(Point3(0, 0, -1), 0.5, std::make_shared<Lambertian>(Color(0.7, 0.3, 0.3))));
+    world.add(std::make_shared<Sphere>(Point3(0, -100.5, -1), 100, std::make_shared<Lambertian>(Color(0.8, 0.8, 0.8))));
+
+    world.add(std::make_shared<Sphere>(Point3(1, 0, -1), 0.5, std::make_shared<Metal>(Color(0.8, 0.6, 0.2))));
+    world.add(std::make_shared<Sphere>(Point3(-1, 0, -1), 0.5, std::make_shared<Metal>(Color(0.8, 0.8, 0.8))));
 
     Camera cam;