three.js/examples/js/interactive/SelectionBox.js

( function () {

	/**
 * This is a class to check whether objects are in a selection area in 3D space
 */

	var SelectionBox = function () {

		var frustum = new THREE.Frustum();
		var center = new THREE.Vector3();
		var tmpPoint = new THREE.Vector3();
		var vecNear = new THREE.Vector3();
		var vecTopLeft = new THREE.Vector3();
		var vecTopRight = new THREE.Vector3();
		var vecDownRight = new THREE.Vector3();
		var vecDownLeft = new THREE.Vector3();
		var vecFarTopLeft = new THREE.Vector3();
		var vecFarTopRight = new THREE.Vector3();
		var vecFarDownRight = new THREE.Vector3();
		var vecFarDownLeft = new THREE.Vector3();
		var vectemp1 = new THREE.Vector3();
		var vectemp2 = new THREE.Vector3();
		var vectemp3 = new THREE.Vector3();

		function SelectionBox( camera, scene, deep ) {

			this.camera = camera;
			this.scene = scene;
			this.startPoint = new THREE.Vector3();
			this.endPoint = new THREE.Vector3();
			this.collection = [];
			this.deep = deep || Number.MAX_VALUE;

		}

		SelectionBox.prototype.select = function ( startPoint, endPoint ) {

			this.startPoint = startPoint || this.startPoint;
			this.endPoint = endPoint || this.endPoint;
			this.collection = [];
			this.updateFrustum( this.startPoint, this.endPoint );
			this.searchChildInFrustum( frustum, this.scene );
			return this.collection;

		};

		SelectionBox.prototype.updateFrustum = function ( startPoint, endPoint ) {

			startPoint = startPoint || this.startPoint;
			endPoint = endPoint || this.endPoint; // Avoid invalid frustum

			if ( startPoint.x === endPoint.x ) {

				endPoint.x += Number.EPSILON;

			}

			if ( startPoint.y === endPoint.y ) {

				endPoint.y += Number.EPSILON;

			}

			this.camera.updateProjectionMatrix();
			this.camera.updateMatrixWorld();

			if ( this.camera.isPerspectiveCamera ) {

				tmpPoint.copy( startPoint );
				tmpPoint.x = Math.min( startPoint.x, endPoint.x );
				tmpPoint.y = Math.max( startPoint.y, endPoint.y );
				endPoint.x = Math.max( startPoint.x, endPoint.x );
				endPoint.y = Math.min( startPoint.y, endPoint.y );
				vecNear.setFromMatrixPosition( this.camera.matrixWorld );
				vecTopLeft.copy( tmpPoint );
				vecTopRight.set( endPoint.x, tmpPoint.y, 0 );
				vecDownRight.copy( endPoint );
				vecDownLeft.set( tmpPoint.x, endPoint.y, 0 );
				vecTopLeft.unproject( this.camera );
				vecTopRight.unproject( this.camera );
				vecDownRight.unproject( this.camera );
				vecDownLeft.unproject( this.camera );
				vectemp1.copy( vecTopLeft ).sub( vecNear );
				vectemp2.copy( vecTopRight ).sub( vecNear );
				vectemp3.copy( vecDownRight ).sub( vecNear );
				vectemp1.normalize();
				vectemp2.normalize();
				vectemp3.normalize();
				vectemp1.multiplyScalar( this.deep );
				vectemp2.multiplyScalar( this.deep );
				vectemp3.multiplyScalar( this.deep );
				vectemp1.add( vecNear );
				vectemp2.add( vecNear );
				vectemp3.add( vecNear );
				var planes = frustum.planes;
				planes[ 0 ].setFromCoplanarPoints( vecNear, vecTopLeft, vecTopRight );
				planes[ 1 ].setFromCoplanarPoints( vecNear, vecTopRight, vecDownRight );
				planes[ 2 ].setFromCoplanarPoints( vecDownRight, vecDownLeft, vecNear );
				planes[ 3 ].setFromCoplanarPoints( vecDownLeft, vecTopLeft, vecNear );
				planes[ 4 ].setFromCoplanarPoints( vecTopRight, vecDownRight, vecDownLeft );
				planes[ 5 ].setFromCoplanarPoints( vectemp3, vectemp2, vectemp1 );
				planes[ 5 ].normal.multiplyScalar( - 1 );

			} else if ( this.camera.isOrthographicCamera ) {

				var left = Math.min( startPoint.x, endPoint.x );
				var top = Math.max( startPoint.y, endPoint.y );
				var right = Math.max( startPoint.x, endPoint.x );
				var down = Math.min( startPoint.y, endPoint.y );
				vecTopLeft.set( left, top, - 1 );
				vecTopRight.set( right, top, - 1 );
				vecDownRight.set( right, down, - 1 );
				vecDownLeft.set( left, down, - 1 );
				vecFarTopLeft.set( left, top, 1 );
				vecFarTopRight.set( right, top, 1 );
				vecFarDownRight.set( right, down, 1 );
				vecFarDownLeft.set( left, down, 1 );
				vecTopLeft.unproject( this.camera );
				vecTopRight.unproject( this.camera );
				vecDownRight.unproject( this.camera );
				vecDownLeft.unproject( this.camera );
				vecFarTopLeft.unproject( this.camera );
				vecFarTopRight.unproject( this.camera );
				vecFarDownRight.unproject( this.camera );
				vecFarDownLeft.unproject( this.camera );
				var planes = frustum.planes;
				planes[ 0 ].setFromCoplanarPoints( vecTopLeft, vecFarTopLeft, vecFarTopRight );
				planes[ 1 ].setFromCoplanarPoints( vecTopRight, vecFarTopRight, vecFarDownRight );
				planes[ 2 ].setFromCoplanarPoints( vecFarDownRight, vecFarDownLeft, vecDownLeft );
				planes[ 3 ].setFromCoplanarPoints( vecFarDownLeft, vecFarTopLeft, vecTopLeft );
				planes[ 4 ].setFromCoplanarPoints( vecTopRight, vecDownRight, vecDownLeft );
				planes[ 5 ].setFromCoplanarPoints( vecFarDownRight, vecFarTopRight, vecFarTopLeft );
				planes[ 5 ].normal.multiplyScalar( - 1 );

			} else {

				console.error( 'THREE.SelectionBox: Unsupported camera type.' );

			}

		};

		SelectionBox.prototype.searchChildInFrustum = function ( frustum, object ) {

			if ( object.isMesh || object.isLine || object.isPoints ) {

				if ( object.material !== undefined ) {

					if ( object.geometry.boundingSphere === null ) object.geometry.computeBoundingSphere();
					center.copy( object.geometry.boundingSphere.center );
					center.applyMatrix4( object.matrixWorld );

					if ( frustum.containsPoint( center ) ) {

						this.collection.push( object );

					}

				}

			}

			if ( object.children.length > 0 ) {

				for ( var x = 0; x < object.children.length; x ++ ) {

					this.searchChildInFrustum( frustum, object.children[ x ] );

				}

			}

		};

		return SelectionBox;

	}();

	THREE.SelectionBox = SelectionBox;

} )();