Design

The SpaceMission MIDlet is a 3D game where the user shoots aliens on a space planet.

The following figure shows the splash screen that is displayed when the MIDlet is launched.

Figure: SpaceMission splash screen

During the game, the user can move around the planet using the device keyboard. The mission is to shoot (freeze) aliens while remaining on the planet surface (if the user steps off the edge of the planet, the game ends).

Figure: Playing the game

To win the game, the user must freeze all the aliens on the planet.

Figure: Winning the game

The MIDlet consists of the following classes:

• GameMIDlet—MIDlet main class, which starts up the MIDlet and loads some static objects, such as images.

• GameStatusListener—Defines the reasons why the game ended.

• SplashScreenView—Represents the splash screen that is shown when the MIDlet is started and the game is loading.

• GameCanvasView—Draws the game elements on the screen. The class keeps a record of the current score, checks for user input, and continuously updates the game status and game screen using a thread.

• FloorTiles—Draws a background image that is repeated from a number of small tiles (in practice, the surface of the planet, which is made up of a number of tiles representing different areas of the terrain). The class constructs a Mesh object, which is returned by the getFloorMesh method.

• PlayerModel—Keeps track of all player-related data, like position and direction. The class also updates this data when it receives a notification that a key has been pressed.

• Game3DManager—Constructs the 3D scene graph used in the game and changes the game state depending on the user input (key presses or touch input). The class also checks for any collisions between the user and the 3D objects in the scene.

• AlienModel—Constructs a Mesh that represents an alien.

• GameSoundManager—Loads the MIDI and sound files used in the game, and plays any tones needed by the game.

• Softkey—Adds custom softkeys to the MIDlet UI.

For information about implementing the MIDlet, see section Implementation.