three.js/examples/js/controls/MouseControls.js

/**
 * @author dmarcos / http://github.com/dmarcos
 *
 * This controls allow to change the orientation of the camera using the mouse
 */

THREE.MouseControls = function ( object ) {

	var scope = this;
	var PI_2 = Math.PI / 2;
	var mouseQuat = {
		x: new THREE.Quaternion(),
		y: new THREE.Quaternion()
	};
	var object = object;
	var xVector = new THREE.Vector3( 1, 0, 0 );
	var yVector = new THREE.Vector3( 0, 1, 0 );

	var onMouseMove = function ( event ) {

		if ( scope.enabled === false ) return;

		var orientation = scope.orientation;

		var movementX = event.movementX || event.mozMovementX || event.webkitMovementX || 0;
		var movementY = event.movementY || event.mozMovementY || event.webkitMovementY || 0;

		orientation.y += movementX * 0.0025;
		orientation.x += movementY * 0.0025;

		orientation.x = Math.max( - PI_2, Math.min( PI_2, orientation.x ) );

	};

	this.enabled = true;

	this.orientation = {
		x: 0,
		y: 0,
	};

	this.update = function() {

		if ( this.enabled === false ) return;

		mouseQuat.x.setFromAxisAngle( xVector, this.orientation.x );
		mouseQuat.y.setFromAxisAngle( yVector, this.orientation.y );
		object.quaternion.copy( mouseQuat.y ).multiply( mouseQuat.x );
		return;

	};

	this.dispose = function() {

		document.removeEventListener( 'mousemove', onMouseMove, false );

	}

	document.addEventListener( 'mousemove', onMouseMove, false );

};