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Killer Game Programming in Java
book

Killer Game Programming in Java

by Andrew Davison
May 2005
Intermediate to advanced content levelIntermediate to advanced
998 pages
26h
English
O'Reilly Media, Inc.
Content preview from Killer Game Programming in Java

Worm Obstacles

The Obstacles object maintains an array of Rectangle objects called boxes. Each object contains the top-left hand coordinate of a box and the length of its square sides.

The public methods in the Obstacles class are synchronized since the event thread of the game could add a box to the obstacles list (via a call to add()) while the animation thread is examining or drawing the list.

add() is defined as

    synchronized public void add(int x, int y)
    {
      boxes.add( new Rectangle(x,y, BOX_LENGTH, BOX_LENGTH));
      wcTop.setBoxNumber( boxes.size() );   // report new no. of boxes
    }

The method updates the boxes text field at the top-level of the game by calling setBoxNumber().

WormPanel delegates the task of drawing the obstacles to the Obstacles object, by calling draw():

    synchronized public void draw(Graphics g)
    // draw a series of blue boxes
    {
      Rectangle box;
      g.setColor(Color.blue);
      for(int i=0; i < boxes.size(); i++) {
        box = (Rectangle) boxes.get(i);
        g.fillRect( box.x, box.y, box.width, box.height);
      }
    }  // end of draw()

Worm communicates with Obstacles to determine if its new head (a Point object, p) intersects with any of the boxes:

    synchronized public boolean hits(Point p, int size)
    {
      Rectangle r = new Rectangle(p.x, p.y, size, size);
      Rectangle box;
      for(int i=0; i < boxes.size(); i++) {
        box = (Rectangle) boxes.get(i);
        if (box.intersects(r))
          return true;
      }
      return false;
    }  // end of hits()
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Publisher Resources

ISBN: 0596007302Supplemental ContentErrata Page