title: How to get mouse position in three.js along z axis
body: <p>So the idea is to create A plane at z = 0 and infinite x y.</p>
  
  <p>then make A ray from the mouse position and find where it intersects.</p>
  
  <p>I'm not sure how to create that plane and I don't know if the is the best way.</p>
  
  <p>also this is a 2d scene and everything is on the z = 0</p>
  
  <pre><code>        var projector = new THREE.Projector();
          var  mouse_vector = new THREE.Vector3();
          var mouse = { x: 0, y: 0, z: 1 };
          ray = new THREE.Raycaster( new THREE.Vector3(0,0,0), new THREE.Vector3(0,0,0) ),
          var intersects = [];
          event_info.preventDefault(); 
          mouse.x = ( event_info.clientX / window.innerWidth ) * 2 – 1;
          mouse.y = – ( event_info.clientY / window.innerHeight ) * 2 + 1;
          mouse_vector.set( mouse.x, mouse.y, mouse.z );
          projector.unprojectVector( mouse_vector, camera );
          var direction = mouse_vector.sub( camera.position ).normalize();
          ray = ray.set( camera.position, direction );
  
  
  
          var plane = new THREE.Plane();
          plane.set(v1, v2, v3);
          var where = ray.intersectPlane (plane);
  
          intersects = ray.intersectPlane( Plane );
  
              alert(intersects);
  
          }
  </code></pre>