I have building project with three.js... canvas where you can drag object and play with the camera view as well... there is a famous example- "Draggable Cubes", well m
in this line :
var vector = new THREE.Vector3( mouse.x, mouse.y, 0.5 );
You use the mouse Vector2 object but you don't initialize it.
Something like this should work :
mouse.x = +(event.targetTouches[0].pageX / window.innerwidth) * 2 +-1;
mouse.y = -(event.targetTouches[0].pageY / window.innerHeight) * 2 + 1;