src/volume/csg/Operation.js

import { Box3 } from "three";
 
/**
 * A CSG operation.
 */
 
export class Operation {
 
	/**
	 * Constructs a new operation.
	 *
	 * @param {OperationType} type - The type of this operation.
	 * @param {Operation} ...children - Child operations.
	 */
 
	constructor(type, ...children) {
 
		/**
		 * The type of this operation.
		 *
		 * @type {OperationType}
		 */
 
		this.type = type;
 
		/**
		 * A list of operations.
		 *
		 * Right-hand side operands have precedence, meaning that the result of the
		 * first item in the list will be dominated by the result of the second one,
		 * etc.
		 *
		 * @type {Operation[]}
		 * @private
		 */
 
		this.children = children;
 
		/**
		 * The bounding box of this operation.
		 *
		 * @type {Box3}
		 * @private
		 */
 
		this.boundingBox = null;
 
	}
 
	/**
	 * Calculates the complete bounding box of this CSG operation if it doesn't
	 * exist yet and returns it.
	 *
	 * @return {Box3} The bounding box.
	 */
 
	getBoundingBox() {
 
		if(this.boundingBox === null) {
 
			this.boundingBox = this.computeBoundingBox();
 
		}
 
		return this.boundingBox;
 
	}
 
	/**
	 * Calculates the bounding box of this CSG operation while taking all child
	 * operations into account.
	 *
	 * @return {Box3} The bounding box.
	 */
 
	computeBoundingBox() {
 
		const children = this.children;
		const boundingBox = new Box3();
 
		let i, l;
 
		for(i = 0, l = children.length; i < l; ++i) {
 
			boundingBox.union(children[i].getBoundingBox());
 
		}
 
		return boundingBox;
 
	}
 
}