95 lines
2.4 KiB
C++
95 lines
2.4 KiB
C++
#ifndef MATERIAL_H
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#define MATERIAL_H
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#include "hittable.h"
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#include "rtweekend.h"
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#include "vec3.h"
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struct hit_record;
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class material {
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public:
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virtual bool scatter(const ray& r_in, const hit_record& rec, color& attenuation, ray& scattered) const = 0;
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};
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class lambertian : public material {
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public:
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lambertian(const color& a) : albedo(a) {}
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bool scatter(
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const ray &r_in, const hit_record &rec, color &attenuation, ray &scattered
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) const override {
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auto scatter_direction = rec.normal + random_in_hemisphere(rec.normal);
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// Catch degenerate scatter direction
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if (scatter_direction.near_zero())
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scatter_direction = rec.normal;
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scattered = ray(rec.p, scatter_direction);
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attenuation = albedo;
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return true;
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}
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public:
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color albedo;
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};
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class metal : public material {
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public:
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metal(const color& a, double f) : albedo(a), fuzz(f < 1 ? f : 1) {}
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bool scatter(
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const ray &r_in, const hit_record &rec, color &attenuation, ray &scattered
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) const override {
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vec3 reflected = reflect(unit_vector(r_in.direction()), rec.normal);
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scattered = ray(rec.p, reflected + fuzz*random_in_hemisphere(rec.normal));
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attenuation = albedo;
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return (dot(scattered.direction(), rec.normal) > 0);
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}
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public:
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color albedo;
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double fuzz;
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};
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class dialectric : public material {
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public:
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dialectric(double index_of_refraction): ir(index_of_refraction) {}
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bool scatter(
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const ray &r_in, const hit_record &rec, color &attenuation, ray &scattered
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) const override {
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attenuation = color(1.0, 1.0, 1.0);
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double refraction_ratio = rec.front_face ? (1.0/ir) : ir;
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vec3 unit_direction = unit_vector(r_in.direction());
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double cos_theta = fmin(dot(-unit_direction, rec.normal), 1.0);
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double sin_theta = sqrt(1 - cos_theta*cos_theta);
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bool cannot_refract = refraction_ratio * sin_theta > 1.0;
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vec3 direction;
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if (cannot_refract || reflectance(cos_theta, refraction_ratio) > random_double())
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direction = reflect(unit_direction, rec.normal);
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else
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direction = refract(unit_direction, rec.normal, refraction_ratio);
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scattered = ray(rec.p, direction);
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return true;
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}
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public:
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double ir; // Index of Refraction
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private:
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static double reflectance(double cosine, double ref_idx) {
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// Use Schlick's approximation for reflectance
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auto r0 = (1-ref_idx) /(1+ref_idx);
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r0 = r0*r0;
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return r0 + (1-r0)*pow((1 - cosine), 5);
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}
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};
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#endif
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