Add basic function for model picking. Needs to be addressed by #29.

Entities/EntityList.cs

@@ -1,4 +1,5 @@
 using System;
+using OpenTK;
 
 namespace ClassicalSharp {
 
@@ -31,6 +32,24 @@ namespace ClassicalSharp {
 			}
 		}
 		
+		public byte GetClosetPlayer( Vector3 eyePos, Vector3 dir ) {
+			float dist = float.PositiveInfinity;
+			byte targetId = 255;
+			
+			for( int i = 0; i < Players.Length - 1; i++ ) { // -1 because we don't want to pick against local player
+				Player p = Players[i];
+				if( p == null ) continue;
+				BoundingBox bounds = p.Bounds;
+				
+				float t0, t1;
+				if( IntersectionUtils.RayIntersectsBox( eyePos, dir, bounds.Min, bounds.Max, out t0, out t1 ) ) {
+					dist = t0;
+					targetId = (byte)i;
+				}
+			}
+			return targetId;
+		}
+		
 		public Player this[int id] {
 			get { return Players[id]; }
 			set { Players[id] = value; }