three.js/src/extras/helpers/BoxHelper.js

/**
 * @author mrdoob / http://mrdoob.com/
 */

THREE.BoxHelper = function ( object ) {

	var geometry = new THREE.BufferGeometry();
	geometry.addAttribute( 'position', new THREE.BufferAttribute( new Float32Array( 72 ), 3 ) );

	THREE.LineSegments.call( this, geometry, new THREE.LineBasicMaterial( { color: 0xffff00 } ) );

	if ( object !== undefined ) {

		this.update( object );

	}

};

THREE.BoxHelper.prototype = Object.create( THREE.LineSegments.prototype );
THREE.BoxHelper.prototype.constructor = THREE.BoxHelper;

THREE.BoxHelper.prototype.update = ( function () {

	var box = new THREE.Box3();

	return function ( object ) {

		box.setFromObject( object );

		var min = box.min;
		var max = box.max;

		/*
		  5____4
		1/___0/|
		| 6__|_7
		2/___3/

		0: max.x, max.y, max.z
		1: min.x, max.y, max.z
		2: min.x, min.y, max.z
		3: max.x, min.y, max.z
		4: max.x, max.y, min.z
		5: min.x, max.y, min.z
		6: min.x, min.y, min.z
		7: max.x, min.y, min.z
		*/

		var vertices = this.geometry.attributes.position.array;

		vertices[  0 ] = max.x; vertices[  1 ] = max.y; vertices[  2 ] = max.z;
		vertices[  3 ] = min.x; vertices[  4 ] = max.y; vertices[  5 ] = max.z;

		vertices[  6 ] = min.x; vertices[  7 ] = max.y; vertices[  8 ] = max.z;
		vertices[  9 ] = min.x; vertices[ 10 ] = min.y; vertices[ 11 ] = max.z;

		vertices[ 12 ] = min.x; vertices[ 13 ] = min.y; vertices[ 14 ] = max.z;
		vertices[ 15 ] = max.x; vertices[ 16 ] = min.y; vertices[ 17 ] = max.z;

		vertices[ 18 ] = max.x; vertices[ 19 ] = min.y; vertices[ 20 ] = max.z;
		vertices[ 21 ] = max.x; vertices[ 22 ] = max.y; vertices[ 23 ] = max.z;

		//

		vertices[ 24 ] = max.x; vertices[ 25 ] = max.y; vertices[ 26 ] = min.z;
		vertices[ 27 ] = min.x; vertices[ 28 ] = max.y; vertices[ 29 ] = min.z;

		vertices[ 30 ] = min.x; vertices[ 31 ] = max.y; vertices[ 32 ] = min.z;
		vertices[ 33 ] = min.x; vertices[ 34 ] = min.y; vertices[ 35 ] = min.z;

		vertices[ 36 ] = min.x; vertices[ 37 ] = min.y; vertices[ 38 ] = min.z;
		vertices[ 39 ] = max.x; vertices[ 40 ] = min.y; vertices[ 41 ] = min.z;

		vertices[ 42 ] = max.x; vertices[ 43 ] = min.y; vertices[ 44 ] = min.z;
		vertices[ 45 ] = max.x; vertices[ 46 ] = max.y; vertices[ 47 ] = min.z;

		//

		vertices[ 48 ] = max.x; vertices[ 49 ] = max.y; vertices[ 50 ] = max.z;
		vertices[ 51 ] = max.x; vertices[ 52 ] = max.y; vertices[ 53 ] = min.z;

		vertices[ 54 ] = min.x; vertices[ 55 ] = max.y; vertices[ 56 ] = max.z;
		vertices[ 57 ] = min.x; vertices[ 58 ] = max.y; vertices[ 59 ] = min.z;

		vertices[ 60 ] = min.x; vertices[ 61 ] = min.y; vertices[ 62 ] = max.z;
		vertices[ 63 ] = min.x; vertices[ 64 ] = min.y; vertices[ 65 ] = min.z;

		vertices[ 66 ] = max.x; vertices[ 67 ] = min.y; vertices[ 68 ] = max.z;
		vertices[ 69 ] = max.x; vertices[ 70 ] = min.y; vertices[ 71 ] = min.z;

		this.geometry.attributes.position.needsUpdate = true;

		this.geometry.computeBoundingSphere();

	}

} )();