Add follow entity to holograms

Plugins/Mineplex.Core/src/mineplex/core/hologram/Hologram.java

@@ -19,6 +19,7 @@ import net.minecraft.server.v1_7_R4.PacketPlayOutSpawnEntityLiving;
 
 import org.bukkit.Location;
 import org.bukkit.craftbukkit.v1_7_R4.entity.CraftPlayer;
+import org.bukkit.entity.Entity;
 import org.bukkit.entity.Player;
 import org.bukkit.util.Vector;
 
@@ -40,6 +41,8 @@ public class Hologram
      * 1.7 packets uses both EntityIDs while 1.8 uses only the first.
      */
     private ArrayList<Entry<Integer, Integer>> _entityIds = new ArrayList<Entry<Integer, Integer>>();
+    private Entity _followEntity;
+    private HologramManager _hologramManager;
     private boolean _isWitherSkull;
     /**
      * Keeps track of the holograms movements. This fixes offset that occasionally happens when moving a hologram around.
@@ -54,7 +57,7 @@ public class Hologram
     private HologramTarget _target = HologramTarget.BLACKLIST;
     private String[] _text = new String[0];
     private int _viewDistance = 70;
-    private HologramManager _hologramManager;
+    protected Vector relativeToEntity;
 
     public Hologram(HologramManager hologramManager, Location location, String... text)
     {
@@ -106,6 +109,11 @@ public class Hologram
         return UtilPlayer.is1_8(player) ? _destroy1_8 : _destroy1_7;
     }
 
+    public Entity getEntityFollowing()
+    {
+        return _followEntity;
+    }
+
     /**
      * Get who can see the hologram
      * 
@@ -138,6 +146,11 @@ public class Hologram
         return nearbyPlayers;
     }
 
+    protected ArrayList<Player> getPlayersTracking()
+    {
+        return _playersTracking;
+    }
+
     protected Packet[] getSpawnPackets(Player player)
     {
         if (_makePackets)
@@ -348,6 +361,19 @@ public class Hologram
         return this;
     }
 
+    /**
+     * If the entity moves, the hologram will update its position to appear relative to the movement.
+     * 
+     * @Please note the hologram updates every tick.
+     */
+    public Hologram setFollowEntity(Entity entityToFollow)
+    {
+        _followEntity = entityToFollow;
+        relativeToEntity = entityToFollow == null ? null : this._location.clone().subtract(entityToFollow.getLocation())
+                .toVector();
+        return this;
+    }
+
     /**
      * Set who can see the hologram
      * 
@@ -368,6 +394,11 @@ public class Hologram
         _makePackets = true;
         Location oldLocation = getLocation();
         _location = newLocation.clone();
+        // TODO Needs to set the new relativeToEntity
+        if (getEntityFollowing() != null)
+        {
+            relativeToEntity = _location.clone().subtract(getEntityFollowing().getLocation()).toVector();
+        }
         if (isInUse())
         {
             ArrayList<Player> canSee = getNearbyPlayers();
@@ -571,11 +602,6 @@ public class Hologram
         return setLocation(getLocation());
     }
 
-    protected ArrayList<Player> getPlayersTracking()
-    {
-        return _playersTracking;
-    }
-
     /**
      * Start the hologram
      */

Plugins/Mineplex.Core/src/mineplex/core/hologram/HologramManager.java

@@ -11,11 +11,13 @@ import net.minecraft.server.v1_7_R4.Packet;
 import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_7_R4.entity.CraftPlayer;
+import org.bukkit.entity.Entity;
 import org.bukkit.entity.Player;
 import org.bukkit.event.EventHandler;
 import org.bukkit.event.EventPriority;
 import org.bukkit.event.Listener;
 import org.bukkit.plugin.java.JavaPlugin;
+import org.bukkit.util.Vector;
 
 public class HologramManager implements Listener
 {
@@ -53,6 +55,18 @@ public class HologramManager implements Listener
             }
             else
             {
+                if (hologram.getEntityFollowing() != null)
+                {
+                    Entity following = hologram.getEntityFollowing();
+                    if (!hologram.relativeToEntity.equals(following.getLocation().subtract(hologram.getLocation()).toVector()))
+                    {
+                        // And we do this so in the rare offchance it changes by a decimal. It doesn't start turning wonky.
+                        Vector vec = hologram.relativeToEntity.clone();
+                        hologram.setLocation(following.getLocation().add(hologram.relativeToEntity));
+                        hologram.relativeToEntity = vec;
+                        continue; // No need to do the rest of the code as setLocation does it.
+                    }
+                }
                 ArrayList<Player> canSee = hologram.getNearbyPlayers();
                 Iterator<Player> itel2 = hologram.getPlayersTracking().iterator();
                 while (itel2.hasNext())