Implement more types of heuristics

Signed-off-by: Chris Cromer <chris@cromer.cl>

src/main/java/cl/cromer/azaraka/Constants.java

@@ -34,6 +34,10 @@ public interface Constants {
 	 * The name of the game
 	 */
 	String TITLE = "La Aventura de Azaraka";
+	/**
+	 * The heuristic to use in the AI distance calculations
+	 */
+	AIHeuristic aIHeuristic = AIHeuristic.MANHATTAN;
 	/**
 	 * Which type of AI to use
 	 */
@@ -186,6 +190,24 @@ public interface Constants {
 		}
 	}
 
+	/**
+	 * The different heuristics that the AI uses to calculate distance
+	 */
+	enum AIHeuristic {
+		/**
+		 * Used for 4 direction movements
+		 */
+		MANHATTAN,
+		/**
+		 * Used for 8 direction movements
+		 */
+		DIAGONAL,
+		/**
+		 * Used for distance between 2 points
+		 */
+		EUCLIDEAN
+	}
+
 	/**
 	 * The different AI that can be used by the player
 	 */

src/main/java/cl/cromer/azaraka/ai/PlayerAI.java

@@ -22,6 +22,7 @@ import cl.cromer.azaraka.object.Portal;
 import cl.cromer.azaraka.sprite.Animation;
 
 import java.awt.event.KeyEvent;
+import java.awt.geom.Point2D;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -52,28 +53,36 @@ public interface PlayerAI extends Runnable, Constants {
 
 	/**
 	 * The heuristic to get the distance between the start state and the end state
-	 *
+	 * <p>
 	 * Manhattan Distance
 	 * Used for 4 direction movements
-	 *      h = abs (current_cell.x – goal.x) +
-	 *          abs (current_cell.y – goal.y)
-	 *
+	 * h = abs (current_cell.x – goal.x) +
+	 * abs (current_cell.y – goal.y)
+	 * <p>
 	 * Diagonal Distance
 	 * Used for 8 direction movements
-	 *      h = max { abs(current_cell.x – goal.x),
-	 *                abs(current_cell.y – goal.y) }
-	 *
+	 * h = max { abs(current_cell.x – goal.x),
+	 * abs(current_cell.y – goal.y) }
+	 * <p>
 	 * Euclidean Distance
 	 * Used for distance between 2 points
-	 *      h = sqrt ( (current_cell.x – goal.x)2 +
-	 *                 (current_cell.y – goal.y)2 )
+	 * h = sqrt ( (current_cell.x – goal.x)2 +
+	 * (current_cell.y – goal.y)2 )
 	 *
 	 * @param start The start state
 	 * @param goal  The goal state
 	 * @return Returns the distance between the states
 	 */
 	default double heuristic(State start, State goal) {
-		return Math.abs(start.getX() - goal.getX()) + Math.abs(start.getY() - goal.getY());
+		switch (aIHeuristic) {
+			case DIAGONAL:
+				return Math.max(Math.abs(start.getX() - goal.getX()), Math.abs(start.getY() - goal.getY()));
+			case EUCLIDEAN:
+				return Point2D.distance(start.getX(), start.getY(), goal.getX(), goal.getY());
+			case MANHATTAN:
+			default:
+				return Math.abs(start.getX() - goal.getX()) + Math.abs(start.getY() - goal.getY());
+		}
 	}
 
 	/**

src/main/java/cl/cromer/azaraka/ai/PlayerAStarAI.java

@@ -504,7 +504,7 @@ public class PlayerAStarAI extends AI implements PlayerAI, Constants {
 		 * Initialize the enemy cost and level
 		 *
 		 * @param level The level
-		 * @param cost The cost
+		 * @param cost  The cost
 		 */
 		EnemyCost(int level, int cost) {
 			this.level = level;