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Refraction

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This commit is contained in:
Armin Friedl 2022-07-30 18:41:07 +02:00
parent 7c2cead577
commit 8f7a44935a
3 changed files with 97 additions and 73 deletions
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95
rtiww/src/main.cpp
View file

@ -12,71 +12,72 @@
#include <memory> #include <memory>
color ray_color(const ray &r, const hittable &world, int depth) { color ray_color(const ray &r, const hittable &world, int depth) {
hit_record rec; hit_record rec;
// If we've exceeded the ray bounce limit, no more light is gathered. // If we've exceeded the ray bounce limit, no more light is gathered.
if (depth <= 0) if (depth <= 0)
return color(0,0,0); return color(0, 0, 0);
if (world.hit(r, 0.000001, infinity, rec)) { if (world.hit(r, 0.000001, infinity, rec)) {
ray scattered; ray scattered;
color attenuation; color attenuation;
if (rec.mat_ptr->scatter(r, rec, attenuation, scattered)) if (rec.mat_ptr->scatter(r, rec, attenuation, scattered))
return attenuation * ray_color(scattered, world, depth-1); return attenuation * ray_color(scattered, world, depth - 1);
return color(0,0,0); return color(0, 0, 0);
} }
vec3 unit_direction = unit_vector(r.direction()); vec3 unit_direction = unit_vector(r.direction());
auto t = 0.5*(unit_direction.y() + 1.0); auto t = 0.5 * (unit_direction.y() + 1.0);
return (1.0-t)*color(1.0, 1.0, 1.0) + t*color(0.5, 0.7, 1.0); return (1.0 - t) * color(1.0, 1.0, 1.0) + t * color(0.5, 0.7, 1.0);
} }
int main() { int main() {
// Image // Image
const auto aspect_ratio = 16.0 / 9.0; const auto aspect_ratio = 16.0 / 9.0;
const int image_width = 400; const int image_width = 400;
const int image_height = static_cast<int>(image_width / aspect_ratio); const int image_height = static_cast<int>(image_width / aspect_ratio);
const int samples_per_pixel = 100; const int samples_per_pixel = 100;
const int max_depth = 50; const int max_depth = 50;
// World // World
hittable_list world; hittable_list world;
auto material_ground = make_shared<lambertian>(color(0.8, 0.8, 0.0)); auto material_ground = make_shared<lambertian>(color(0.8, 0.8, 0.0));
auto material_center = make_shared<lambertian>(color(0.7, 0.3, 0.3)); auto material_center = make_shared<dielectric>(1.5);
auto material_left = make_shared<metal>(color(0.8, 0.8, 0.8), 0.3); auto material_left = make_shared<dielectric>(1.5);
auto material_right = make_shared<metal>(color(0.8, 0.6, 0.2), 1.0); auto material_right = make_shared<metal>(color(0.8, 0.6, 0.2), 1.0);
world.add(make_shared<sphere>(point3( 0.0, -100.5, -1.0), 100.0, material_ground)); world.add(
world.add(make_shared<sphere>(point3( 0.0, 0.0, -1.0), 0.5, material_center)); make_shared<sphere>(point3(0.0, -100.5, -1.0), 100.0, material_ground));
world.add(make_shared<sphere>(point3(-1.0, 0.0, -1.0), 0.5, material_left)); world.add(make_shared<sphere>(point3(0.0, 0.0, -1.0), 0.5, material_center));
world.add(make_shared<sphere>(point3( 1.0, 0.0, -1.0), 0.5, material_right)); world.add(make_shared<sphere>(point3(-1.0, 0.0, -1.0), 0.5, material_left));
world.add(make_shared<sphere>(point3(1.0, 0.0, -1.0), 0.5, material_right));
// Camera // Camera
camera cam; camera cam;
// Render // Render
std::cout << "P3\n" << image_width << " " << image_height << "\n255\n"; std::cout << "P3\n" << image_width << " " << image_height << "\n255\n";
for (int j = image_height-1; j >= 0; --j) { for (int j = image_height - 1; j >= 0; --j) {
std::cerr << "\rScanlines remaining: " << j << ' ' << std::flush; std::cerr << "\rScanlines remaining: " << j << ' ' << std::flush;
for (int i = 0; i < image_width; ++i) { for (int i = 0; i < image_width; ++i) {
color pixel_color(0, 0, 0); color pixel_color(0, 0, 0);
for (int s = 0; s < samples_per_pixel; ++s) { for (int s = 0; s < samples_per_pixel; ++s) {
auto u = (i + random_double()) / (image_width-1); auto u = (i + random_double()) / (image_width - 1);
auto v = (j + random_double()) / (image_height-1); auto v = (j + random_double()) / (image_height - 1);
ray r = cam.get_ray(u, v); ray r = cam.get_ray(u, v);
pixel_color += ray_color(r, world, max_depth); pixel_color += ray_color(r, world, max_depth);
} }
write_color(std::cout, pixel_color, samples_per_pixel); write_color(std::cout, pixel_color, samples_per_pixel);
}
} }
}
std::cerr << "\nDone.\n"; std::cerr << "\nDone.\n";
return 0; return 0;
} }

68
rtiww/src/material.h
View file

@ -13,46 +13,62 @@ public:
color &attenuation, ray &scattered) const = 0; color &attenuation, ray &scattered) const = 0;
}; };
class lambertian : public material { class lambertian : public material {
public: public:
lambertian(const color& a) : albedo(a) {} lambertian(const color &a) : albedo(a) {}
virtual bool scatter( virtual bool scatter(const ray &r_in, const hit_record &rec,
const ray& r_in, const hit_record& rec, color& attenuation, ray& scattered color &attenuation, ray &scattered) const override {
) const override { auto scatter_direction = rec.normal + random_in_unit_sphere();
auto scatter_direction = rec.normal+random_in_unit_sphere();
// Catch degenerate scatter direction // Catch degenerate scatter direction
if (scatter_direction.near_zero()) if (scatter_direction.near_zero())
scatter_direction = rec.normal; scatter_direction = rec.normal;
scattered = ray(rec.p, scatter_direction); scattered = ray(rec.p, scatter_direction);
attenuation = albedo; attenuation = albedo;
return true; return true;
} }
public: public:
color albedo; color albedo;
}; };
class metal : public material { class metal : public material {
public: public:
metal(const color& a, double f) : albedo(a), fuzz(f<1 ? f: 1) {} metal(const color &a, double f) : albedo(a), fuzz(f < 1 ? f : 1) {}
virtual bool scatter( virtual bool scatter(const ray &r_in, const hit_record &rec,
const ray& r_in, const hit_record& rec, color& attenuation, ray& scattered color &attenuation, ray &scattered) const override {
) const override { vec3 reflected = reflect(unit_vector(r_in.direction()), rec.normal);
vec3 reflected = reflect(unit_vector(r_in.direction()), rec.normal); scattered = ray(rec.p, reflected + fuzz * random_in_unit_sphere());
scattered = ray(rec.p, reflected + fuzz*random_in_unit_sphere()); attenuation = albedo;
attenuation = albedo; return true;
return true; }
}
public: public:
color albedo; color albedo;
double fuzz; double fuzz;
};
class dielectric : public material {
public:
dielectric(double index_of_refraction) : ir(index_of_refraction) {}
virtual bool scatter(const ray &r_in, const hit_record &rec,
color &attenuation, ray &scattered) const override {
attenuation = color(1.0, 1.0, 1.0);
double refraction_ratio = rec.front_face ? (1.0 / ir) : ir;
vec3 unit_direction = unit_vector(r_in.direction());
vec3 refracted = refract(unit_direction, rec.normal, refraction_ratio);
scattered = ray(rec.p, refracted);
return true;
}
public:
double ir;
}; };
#endif // MATERIAL_H_ #endif // MATERIAL_H_

7
rtiww/src/vec3.h
View file

@ -124,4 +124,11 @@ vec3 random_in_hemisphere(const vec3 &normal) {
vec3 reflect(const vec3 &v, const vec3 &n) { return v - 2 * dot(v, n) * n; } vec3 reflect(const vec3 &v, const vec3 &n) { return v - 2 * dot(v, n) * n; }
vec3 refract(const vec3 &v, const vec3 &n, double etai_over_etat) {
auto cos_theta = fmin(dot(-v, n), 1.0);
vec3 r_out_perp = etai_over_etat * (v + cos_theta * n);
vec3 r_out_parallel = -sqrt(fabs(1.0 - r_out_perp.length_squared())) * n;
return r_out_perp + r_out_parallel;
}
#endif // RTIWW_VEC3_H #endif // RTIWW_VEC3_H