FollowPath.java

package vooga.towerdefense.action.actionlist;

import vooga.towerdefense.action.Action;
import vooga.towerdefense.attributes.AttributeConstantsEnum;
import vooga.towerdefense.gameelements.GameElement;
import vooga.towerdefense.model.Path;
import util.Location;
import util.Vector;


/**
 * Makes the action initiator follow a path.
 * 
 * @author Mattew Roy
 * @author Zhen Gou
 *
 * 
 */

public class FollowPath extends Action {

    private static final double DISTANCE_OFFSET = 5;
    private Path myPath;
    private Location myCurrentPathNode;
    private GameElement myInitiator;

    public FollowPath (GameElement initiator, Path path) {
        super();
        myInitiator = initiator;
        myPath = path;
        changeNode();
    }

    public void executeAction (double elapsedTime) {
        if (myInitiator.getCenter().distance(myCurrentPathNode) < DISTANCE_OFFSET) {
            changeNode();
        }
    }

    /**
     * movement logic, if path has next, change movement direction towards next
     * node, if not, stop moving
     */
    private void changeNode () {
        if (myPath.hasNext()) {
            myCurrentPathNode = myPath.next();
            Vector newDirection = myInitiator
                    .getCenter().difference(myCurrentPathNode);

            // for some reason, the above method gives the wrong sign on the
            // angle. so have to manually reverse its direction. tried negate(), doesn't work
            newDirection =
                    new Vector(-1 * newDirection.getDirection(), newDirection.getMagnitude());

            myInitiator.getAttributeManager()
                    .getAttribute(AttributeConstantsEnum.DIRECTION.toString())
                    .setValue(newDirection.getDirection());
        }

        else {
            // TODO: needs to have an reached end of path thing
            myInitiator.getAttributeManager()
                    .getAttribute(AttributeConstantsEnum.MOVE_SPEED.toString()).setValue(0);
        }

    }

    public void setPath (Path path) {
        myPath = path;
    }

}