backend/libs/three/math/Sphere.js

import { Box3 } from './Box3.js';
import { Vector3 } from './Vector3.js';

const _box = /*@__PURE__*/ new Box3();
const _v1 = /*@__PURE__*/ new Vector3();
const _toFarthestPoint = /*@__PURE__*/ new Vector3();
const _toPoint = /*@__PURE__*/ new Vector3();

class Sphere {
	constructor(center = new Vector3(), radius = -1) {
		this.center = center;
		this.radius = radius;
	}

	set(center, radius) {
		this.center.copy(center);
		this.radius = radius;

		return this;
	}

	setFromPoints(points, optionalCenter) {
		const center = this.center;

		if (optionalCenter !== undefined) {
			center.copy(optionalCenter);
		} else {
			_box.setFromPoints(points).getCenter(center);
		}

		let maxRadiusSq = 0;

		for (let i = 0, il = points.length; i < il; i++) {
			maxRadiusSq = Math.max(maxRadiusSq, center.distanceToSquared(points[i]));
		}

		this.radius = Math.sqrt(maxRadiusSq);

		return this;
	}

	copy(sphere) {
		this.center.copy(sphere.center);
		this.radius = sphere.radius;

		return this;
	}

	isEmpty() {
		return this.radius < 0;
	}

	makeEmpty() {
		this.center.set(0, 0, 0);
		this.radius = -1;

		return this;
	}

	containsPoint(point) {
		return point.distanceToSquared(this.center) <= this.radius * this.radius;
	}

	distanceToPoint(point) {
		return point.distanceTo(this.center) - this.radius;
	}

	intersectsSphere(sphere) {
		const radiusSum = this.radius + sphere.radius;

		return sphere.center.distanceToSquared(this.center) <= radiusSum * radiusSum;
	}

	intersectsBox(box) {
		return box.intersectsSphere(this);
	}

	intersectsPlane(plane) {
		return Math.abs(plane.distanceToPoint(this.center)) <= this.radius;
	}

	clampPoint(point, target) {
		const deltaLengthSq = this.center.distanceToSquared(point);

		target.copy(point);

		if (deltaLengthSq > this.radius * this.radius) {
			target.sub(this.center).normalize();
			target.multiplyScalar(this.radius).add(this.center);
		}

		return target;
	}

	getBoundingBox(target) {
		if (this.isEmpty()) {
			// Empty sphere produces empty bounding box
			target.makeEmpty();
			return target;
		}

		target.set(this.center, this.center);
		target.expandByScalar(this.radius);

		return target;
	}

	applyMatrix4(matrix) {
		this.center.applyMatrix4(matrix);
		this.radius = this.radius * matrix.getMaxScaleOnAxis();

		return this;
	}

	translate(offset) {
		this.center.add(offset);

		return this;
	}

	expandByPoint(point) {
		// from https://github.com/juj/MathGeoLib/blob/2940b99b99cfe575dd45103ef20f4019dee15b54/src/Geometry/Sphere.cpp#L649-L671

		_toPoint.subVectors(point, this.center);

		const lengthSq = _toPoint.lengthSq();

		if (lengthSq > this.radius * this.radius) {
			const length = Math.sqrt(lengthSq);
			const missingRadiusHalf = (length - this.radius) * 0.5;

			// Nudge this sphere towards the target point. Add half the missing distance to radius,
			// and the other half to position. This gives a tighter enclosure, instead of if
			// the whole missing distance were just added to radius.

			this.center.add(_toPoint.multiplyScalar(missingRadiusHalf / length));
			this.radius += missingRadiusHalf;
		}

		return this;
	}

	union(sphere) {
		// from https://github.com/juj/MathGeoLib/blob/2940b99b99cfe575dd45103ef20f4019dee15b54/src/Geometry/Sphere.cpp#L759-L769

		// To enclose another sphere into this sphere, we only need to enclose two points:
		// 1) Enclose the farthest point on the other sphere into this sphere.
		// 2) Enclose the opposite point of the farthest point into this sphere.

		if (this.center.equals(sphere.center) === true) {
			_toFarthestPoint.set(0, 0, 1).multiplyScalar(sphere.radius);
		} else {
			_toFarthestPoint.subVectors(sphere.center, this.center).normalize().multiplyScalar(sphere.radius);
		}

		this.expandByPoint(_v1.copy(sphere.center).add(_toFarthestPoint));
		this.expandByPoint(_v1.copy(sphere.center).sub(_toFarthestPoint));

		return this;
	}

	equals(sphere) {
		return sphere.center.equals(this.center) && sphere.radius === this.radius;
	}

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

export { Sphere };