Prevent a GameObject from leaving a particular region

I'm trying to prevent a GameObject from leaving a particular region. Now the hard part is that the region doesn't have to be rectangular shaped so what I've been doing so far--clamping the x & y values of the GameObject's destination to the min/max bounds of the shape--will not work. I need a to find a way to constrain the GameObject to the shape defined in the class. The GameObject is also a kinematic rigidbody so that make things a bit more difficult.

This is some of the code I have so far (WIP):

Code (CSharp):

1. public class Prisoner2D : Component
2.     {
3.         [SerializeField] private Movement _movement;
4.         [SerializeField] private Collider2D _prison;
5.  
6.         private Bounds _bounds;
7.  
8.         private void Start()
9.         {
10.             _movement.OnStarted.AddListener(MoveTo);
11.             if (_prison != null)
12.             {
13.                 _bounds = _prison.bounds;
14.             }
15.         }
16.  
17.         public void SetPrison(Collider2D prison)
18.         {
19.             _prison = prison;
20.             _bounds = prison.bounds;
21.         }
22.  
23.         public void MoveTo(Vector2 position)
24.         {
25.             Vector2 min;
26.             Vector2 max;
27.  
28.             if (!_prison.gameObject.isStatic)
29.             {
30.                 var bounds = _prison.bounds;
31.                 min = bounds.min;
32.                 max = bounds.max;
33.             }
34.             else
35.             {
36.                 min = _bounds.min;
37.                 max = _bounds.max;
38.             }
39.  
40.             float x = Mathf.Clamp(position.x, min.x, max.x);
41.             float y = Mathf.Clamp(position.y, min.y, max.y);
42.             var destination = new Vector2(x, y);
43.             _movement.MoveTo(destination);
44.         }
45.  
46.         public void MoveTo(Vector3 position)
47.         {
48.             Vector2 position2D = position;
49.             MoveTo(position2D);
50.         }
51.     }

 

Simple approach is to use a different collision layer - http://docs.unity3d.com/Manual/LayerBasedCollision.html