40 lines
1.0 KiB
C++
40 lines
1.0 KiB
C++
#include "vec3.h"
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Vec3 random_in_unit_sphere() {
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while (true) {
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auto p = Vec3::random(-1, 1);
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if (p.length_squared() >= 1) continue;
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return p;
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}
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}
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Vec3 random_unit_vector() {
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auto a = random_double(0, 2*pi);
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auto z = random_double(-1, 1);
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auto r = std::sqrt(1 - z*z);
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return Vec3(r*std::cos(a), r*std::sin(a), z);
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}
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Vec3 random_in_hemisphere(const Vec3& normal) {
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Vec3 in_unit_sphere = random_in_unit_sphere();
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if (dot(in_unit_sphere, normal) > 0.0)
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return in_unit_sphere;
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else
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return -in_unit_sphere;
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}
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Vec3 refract(const Vec3& uv, const Vec3& n, double etai_over_etat) {
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auto cos_theta = dot(-uv, n);
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Vec3 r_out_parallel = etai_over_etat * (uv + cos_theta*n);
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Vec3 r_out_perp = - std::sqrt(1.0 - r_out_parallel.length_squared()) * n;
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return r_out_parallel + r_out_perp;
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}
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Vec3 random_in_unit_disk() {
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while (true) {
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auto p = Vec3(random_double(-1, 1), random_double(-1, 1), 0);
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if (p.length_squared() >= 1) continue;
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return p;
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}
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}
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