three.js/src/math/Spherical.js

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

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