class Versor {
static fromAngles([l, p, g]) {
l *= Math.PI / 360;
p *= Math.PI / 360;
g *= Math.PI / 360;
const sl = Math.sin(l), cl = Math.cos(l);
const sp = Math.sin(p), cp = Math.cos(p);
const sg = Math.sin(g), cg = Math.cos(g);
return [
cl * cp * cg + sl * sp * sg,
sl * cp * cg - cl * sp * sg,
cl * sp * cg + sl * cp * sg,
cl * cp * sg - sl * sp * cg
];
}
static toAngles([a, b, c, d]) {
return [
Math.atan2(2 * (a * b + c * d), 1 - 2 * (b * b + c * c)) * 180 / Math.PI,
Math.asin(Math.max(-1, Math.min(1, 2 * (a * c - d * b)))) * 180 / Math.PI,
Math.atan2(2 * (a * d + b * c), 1 - 2 * (c * c + d * d)) * 180 / Math.PI
];
}
static interpolateAngles(a, b) {
const i = Versor.interpolate(Versor.fromAngles(a), Versor.fromAngles(b));
return t => Versor.toAngles(i(t));
}
static interpolateLinear([a1, b1, c1, d1], [a2, b2, c2, d2]) {
a2 -= a1, b2 -= b1, c2 -= c1, d2 -= d1;
const x = new Array(4);
return t => {
const l = Math.hypot(x[0] = a1 + a2 * t, x[1] = b1 + b2 * t, x[2] = c1 + c2 * t, x[3] = d1 + d2 * t);
x[0] /= l, x[1] /= l, x[2] /= l, x[3] /= l;
return x;
};
}
static interpolate([a1, b1, c1, d1], [a2, b2, c2, d2]) {
let dot = a1 * a2 + b1 * b2 + c1 * c2 + d1 * d2;
if (dot < 0) a2 = -a2, b2 = -b2, c2 = -c2, d2 = -d2, dot = -dot;
if (dot > 0.9995) return Versor.interpolateLinear([a1, b1, c1, d1], [a2, b2, c2, d2]);
const theta0 = Math.acos(Math.max(-1, Math.min(1, dot)));
const x = new Array(4);
const l = Math.hypot(a2 -= a1 * dot, b2 -= b1 * dot, c2 -= c1 * dot, d2 -= d1 * dot);
a2 /= l, b2 /= l, c2 /= l, d2 /= l;
return t => {
const theta = theta0 * t;
const s = Math.sin(theta);
const c = Math.cos(theta);
x[0] = a1 * c + a2 * s;
x[1] = b1 * c + b2 * s;
x[2] = c1 * c + c2 * s;
x[3] = d1 * c + d2 * s;
return x;
};
}
}