import java.awt.*;
/*
 *----------------------------------------------------------------------
 *
 *	Obstacle.java
 */
/**
  	Instances of this class are ammo boxes and rocks.
	Trees extends this class.
@see Tree
 */
/*
 *----------------------------------------------------------------------
 */
public class Obstacle {
  private Point coord;
  private Image texture;
  /*
   *	Border of the obstacle.
   */
  private Polygon poly;
/*
 *----------------------------------------------------------------------
 *
 *	Obstacle
 */
/**
@param t texture with which the obstacle is drawn.
@param x x-coordinate
@param y y-coordinate
@param p the border of the obstacle.
*/
/*
 *----------------------------------------------------------------------
 */
  public Obstacle(Image t, int x, int y, Polygon p) {
    texture = t;
    coord = new Point(x, y);
    poly = new Polygon(p.xpoints, p.ypoints, p.npoints);
    /*
     *	Translate the polygon to the screen coordinate.
     */
    for (int n = 0; n < poly.npoints; n++) {
      poly.xpoints[n] += x;
      poly.ypoints[n] += y;
    }
  }

/*
 *----------------------------------------------------------------------
 *
 *	draw
 */
/**
    Draws the obstacle.
    Can also draw the help polygons for collision detection.
    See <a href="Obstacle.java">Obstacle.java</a> for more details.
 */
/*
 *----------------------------------------------------------------------
 */
  public void draw(Graphics g) {
    g.drawImage(texture, coord.x, coord.y, null);
    /*
     *	Removing the comments on the following lines will
     *	draw the help polygons for collision detection.
     */
//     g.drawPolygon(poly);
//     Rectangle r = poly.getBoundingBox();
//     g.drawRect(r.x, r.y, r.width, r.height);
//     for (int i = 0; i < poly.npoints - 1; i++) {
//       g.drawPolygon(helpPoly(i));
//     }
  }

/*
 *----------------------------------------------------------------------
 *
 *	getPolygon
 */
/**
@return the polygon that defines the border of the obstacle.
*/
/*
 *----------------------------------------------------------------------
 */
  public Polygon getPolygon() {
    return poly;
  }

/*
 *----------------------------------------------------------------------
 *
 *	getCentre
 */
/**
@return centre of the obstacle.
*/
/*
 *----------------------------------------------------------------------
 */
  public Point getCentre() {
    int sumX = 0; 
    int sumY = 0;
    int n;
    for (n = 1; n < poly.npoints; n++) {
      sumX += poly.xpoints[n];
      sumY += poly.ypoints[n];
    }
    return new Point (sumX / (n - 1), sumY / (n - 1));
  }
/*
 *----------------------------------------------------------------------
 *
 *	helpPoly
 */
/**
@param i which point a help polygon is wanted for
@return help polygon for point i and i+1
*/
/*
 *----------------------------------------------------------------------
 */
  public Polygon helpPoly(int i) {    
    Point center = getCentre(); 
    Polygon helpPoly = new Polygon(); 
    helpPoly.addPoint(center.x, center.y);
    helpPoly.addPoint(poly.xpoints[i], poly.ypoints[i]);
    helpPoly.addPoint(poly.xpoints[i + 1], poly.ypoints[i + 1]);
    helpPoly.addPoint(center.x, center.y);
    return helpPoly;  
  }      
}