Due

Objectives

• to manage communication between model, view, and controller
• to handle mouse events

Reading

Introduction

The evil Seeborgs have overrun most of planet Javalon. Only the capital city of Oopsonia remains under Javalonian control. Forward Base Omega is the last of the city's defenses, but its control system was damaged in the last Seeborg attack. Dr. Richard G. James, head of Javalonian computer systems, was almost finished reimplementing the control system but went out for a donut break and was never seen again. Presumably he was captured by the Seeborgs. Fortunately he left a prototype and instructions for completing the control system.

You are Javalon's last hope!

Assignment

Spaceship needs paint reimplemented to draw the Seeborg spaceships correctly (the code that is in paint now simply draws a colored rectangle). Your new version of paint should use the x, y, width, and height fields of the Spaceship object to determine the coordinates to use to draw the ship. Note that those fields are doubles and so must be cast to ints to be passed to the Graphics methods.

OmegaWindow needs to be updated to include classes that implement listeners for mouse movement (to aim the cannon) and mouse clicks (to fire the cannon). Instances of those listener classes must be registered on the view object. The event handlers should invoke the aimCannon and fireCannon methods in the model. There is also code that needs to be added to the actionPerformed method in the TimerListener inner class to update the view by getting the values for score, time left, and energy from the model, displaying those values in the appropriate components, and then redrawing the cannon and spaceships.

Files

• OmegaWindow.java,
• GameView.java,
• GameModel.java,
• OmegaModel.java,
• Spaceship.java,
• Cannon.java,
• Missile.java,
• Sprite.java, and
• RectangularSprite.java.

Advice

• First, add code to the actionPerformed method in the TimerListener inner class that updates the view. The main part of the view (the view object) can be updated by invoking its repaint method. The other parts (scoreDisplay, timeDisplay, and energyDisplay) can be updated by invoking the accessors in the model (the model object) to get the score, time, and energy, and then invoking the components' setText or setBackground methods (the color used for the energy display is (255, x, x) where x is 0 if the cannon is fully charged and 255 if it is completely discharged). To test your code at this stage, run the still unfinished OmegaWindow. You will not be able to aim or fire, but you will be able to see crudely drawn ships flying across the screen.
• Next, rewrite paint in Spaceship. The version of the applet shown above uses one fillOval and one fillArc to draw the Seeborg ships. Running the game now should display nicely drawn ships.
• Once the Seeborg ships are drawn to your liking, create an inner class in OmegaWindow (you can call it FireListener) and in the constructor, create an instance of that class and register it to listen for events from the main game view. FireListener will have to define five methods (see the appropriate page in the Java API documentation to see which five); four should be empty and the other should simply update the model by invoking its fireCannon method. If you test the game at this point, you should be able to fire the cannon (but not aim it).
• Finally, create another inner class (AimListener), and add code to the constructor that creates an instance of that class and registers it to receive mouse movement events from view (again, check the Java API documentation to see which methods this inner class must define, and which once receives the events we're interested in). The event handler method should simply pass to the model's aimCannon method the x- and y-coordinates to which the mouse has moved. You can get those coordinates using the appropriate methods of the event object. At this point you should be able to aim and fire the cannon.

Exercises

Submissions