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material.h
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material.h
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#ifndef MATERIAL_H
#define MATERIAL_H
#include "common.h"
#include "hittable.h"
class Material {
public:
virtual ~Material() = default;
virtual bool scatter(const Ray& r_in, const HitRecord& hit, color& attenuation, Ray& scattered) const = 0;
};
class Lambertian : public Material {
public:
Lambertian(const color& albedo) : m_albedo(albedo) {}
bool scatter(const Ray& r_in, const HitRecord& hit, color& attenuation, Ray& scattered) const override {
vec3 bounce_dir = hit.normal + random_unit_vector();
if (bounce_dir.near_zero())
bounce_dir = hit.normal;
scattered = Ray(hit.p, bounce_dir);
attenuation = m_albedo;
return true;
}
private:
color m_albedo;
};
class SoftDiffuse : public Material {
public:
SoftDiffuse(const color& albedo) : m_albedo(albedo) {}
bool scatter(const Ray& r_in, const HitRecord& hit, color& attenuation, Ray& scattered) const override final {
vec3 bounce_dir = random_vec3_on_hemisphere(hit.normal);
scattered = Ray(hit.p, bounce_dir);
attenuation = m_albedo;
return true;
}
private:
color m_albedo;
};
class Metal : public Material {
public:
Metal(const color& albedo, double fuzz) : m_albedo(albedo), m_fuzz(fuzz) {}
bool scatter(const Ray& r_in, const HitRecord& hit, color& attenuation, Ray& scattered) const override {
vec3 reflected = reflect(unit_vector(r_in.direction()), hit.normal);
vec3 scattered_dir = reflected + m_fuzz*random_unit_vector();
scattered = Ray(hit.p, scattered_dir);
attenuation = m_albedo;
return dot(scattered_dir, hit.normal) > 0;
}
private:
color m_albedo;
double m_fuzz;
};
class Dielectric : public Material {
public:
Dielectric(double index_of_refraction) : m_ir(index_of_refraction) {}
bool scatter(const Ray& r_in, const HitRecord& hit, color& attenuation, Ray& scattered) const override {
attenuation = color(1.0, 1.0, 1.0); // Perfect glass
auto refraction_ratio = hit.front_face ? 1.0/m_ir : m_ir/1.0;
vec3 ray_dir_unit = unit_vector(r_in.direction());
double cos_theta = fmin(dot(-ray_dir_unit, hit.normal), 1.0);
double sin_theta = sqrt(1 - cos_theta * cos_theta);
vec3 direction;
if (refraction_ratio * sin_theta > 1.0 // Over critical angle
|| _schlick_approximation(cos_theta, refraction_ratio) > random_double())
direction = reflect(ray_dir_unit, hit.normal);
else
direction = refract(ray_dir_unit, hit.normal, refraction_ratio);
scattered = Ray(hit.p, direction);
return true;
}
private:
static double _schlick_approximation(double cosine, double ref_idx) {
auto r0 = (1 - ref_idx) / (1 + ref_idx);
r0 = r0 * r0;
return r0 + (1 - r0) * pow((1 - cosine), 5);
}
private:
double m_ir;
};
#endif // MATERIAL_H