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vec3.js
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vec3.js
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export class Vec3 {
constructor(e0, e1, e2) {
this.e = [e0 || 0, e1 || 0, e2 || 0];
}
get x() {
return this.e[0];
}
get y() {
return this.e[1];
}
get z() {
return this.e[2];
}
negated() {
return new Vec3(-this.e[0], -this.e[1], -this.e[2]);
}
addInPlace(v) {
this.e[0] += v.e[0];
this.e[1] += v.e[1];
this.e[2] += v.e[2];
return this;
}
scaleInPlace(t) {
this.e[0] *= t;
this.e[1] *= t;
this.e[2] *= t;
return this;
}
length() {
return Math.sqrt(this.length_squared());
}
length_squared() {
const e = this.e;
return e[0] * e[0] + e[1] * e[1] + e[2] * e[2];
}
near_zero() {
const s = 1e-8;
return (
Math.abs(this.e[0] < s) &&
Math.abs(this.e[1] < s) &&
Math.abs(this.e[2] < s)
);
}
static random() {
return new Vec3(Math.random(), Math.random(), Math.random());
}
static random_in_range(min, max) {
return new Vec3(
min + Math.random() * (max - min),
min + Math.random() * (max - min),
min + Math.random() * (max - min)
);
}
}
export const Color = Vec3;
export const Point3 = Vec3;
// Utility functions
export function add(...vs) {
const result = new Vec3();
for (const v of vs) {
result.e[0] += v.x;
result.e[1] += v.y;
result.e[2] += v.z;
}
return result;
}
export function sub(...vs) {
const result = new Vec3();
result.e[0] = vs[0].x;
result.e[1] = vs[0].y;
result.e[2] = vs[0].z;
for (const v of vs.slice(1)) {
result.e[0] -= v.x;
result.e[1] -= v.y;
result.e[2] -= v.z;
}
return result;
}
export function mul(a, b) {
let u, v, t;
if (a instanceof Vec3) {
[v, t] = [a, b];
} else {
[v, t] = [b, a];
}
if (t instanceof Vec3) {
u = t;
return new Vec3(u.x * v.x, u.y * v.y, u.z * v.z);
} else {
return new Vec3(v.x * t, v.y * t, v.z * t);
}
}
export function dot(u, v) {
return u.x * v.x + u.y * v.y + u.z * v.z;
}
export function cross(u, v) {
return new Vec3(
u.y * v.z - u.z * v.y,
u.z * v.x - u.x * v.z,
u.x * v.y - u.y * v.x
);
}
export function unit_vector(v) {
return mul(v, 1 / v.length());
}
export function reflect(v, n) {
return sub(v, mul(2 * dot(v, n), n));
}
export function refract(uv, n, etai_over_etat) {
const cos_theta = Math.min(dot(mul(-1, uv), n), 1);
const r_out_perp = mul(etai_over_etat, add(uv, mul(cos_theta, n)));
const r_out_parallel = mul(
-Math.sqrt(Math.abs(1 - r_out_perp.length_squared())),
n
);
return add(r_out_perp, r_out_parallel);
}
// Random utilities
export function random_in_unit_sphere() {
while (true) {
const p = Vec3.random_in_range(-1, 1);
if (p.length_squared() >= 1) continue;
return p;
}
}
export function random_unit_vector() {
return unit_vector(random_in_unit_sphere());
}
export function random_in_hemisphere(normal) {
const in_unit_sphere = random_in_unit_sphere();
if (dot(in_unit_sphere, normal) > 0) {
return in_unit_sphere;
} else {
return in_unit_sphere.negated();
}
}
export function random_in_unit_disk() {
while (true) {
const p = new Vec3(-1 + 2 * Math.random(), -1 + 2 * Math.random(), 0);
if (p.length_squared() >= 1) continue;
return p;
}
}