backend/libs/three/math/Spherical.js

/**
 * Ref: https://en.wikipedia.org/wiki/Spherical_coordinate_system
 *
 * The polar angle (phi) is measured from the positive y-axis. The positive y-axis is up.
 * The azimuthal angle (theta) is measured from the positive z-axis.
 */

import * as MathUtils from './MathUtils.js';

class Spherical {
	constructor(radius = 1, phi = 0, theta = 0) {
		this.radius = radius;
		this.phi = phi; // polar angle
		this.theta = theta; // azimuthal angle

		return this;
	}

	set(radius, phi, theta) {
		this.radius = radius;
		this.phi = phi;
		this.theta = theta;

		return this;
	}

	copy(other) {
		this.radius = other.radius;
		this.phi = other.phi;
		this.theta = other.theta;

		return this;
	}

	// restrict phi to be betwee EPS and PI-EPS
	makeSafe() {
		const EPS = 0.000001;
		this.phi = Math.max(EPS, Math.min(Math.PI - EPS, this.phi));

		return this;
	}

	setFromVector3(v) {
		return this.setFromCartesianCoords(v.x, v.y, v.z);
	}

	setFromCartesianCoords(x, y, z) {
		this.radius = Math.sqrt(x * x + y * y + z * z);

		if (this.radius === 0) {
			this.theta = 0;
			this.phi = 0;
		} else {
			this.theta = Math.atan2(x, z);
			this.phi = Math.acos(MathUtils.clamp(y / this.radius, -1, 1));
		}

		return this;
	}

	clone() {
		return new this.constructor().copy(this);
	}
}

export { Spherical };