The Pop display

Pop shows a border box with objects inside that that begin moving after the Enter key is pressed. The program's appearance and behavior are independent of the size of the window and, within certain limits, the speed of your processor.

Pop is a multiple document interface program, and it is possible to open up several Pop games or views of the games at once, with all the games and views running at the same time.

The way to open an additional view of a game session already open is to use Window | Additional View of Current Game. Opening an additional view of a game can be useful, as you can look at the game from two different viewpoints in the different views.

The way to open a window on a different game is to use the File | New Game Window control. There is in fact little point in opening more than one game at once, but we have this feature for the sake of completeness.

In practice, running multiple game windows makes the update speed quite low. The program limits you to opening at most four windows at once.

When the main Pop window is not the focus window on the Windows desktop, the animation of all the games and views is paused.

The moving objects in a Pop game are called critters. Each critter has an associated sprite, which is what you see. In some games you have the option of changing the kinds of sprites that are attached to the critters, so as to experiment with different design possibilities.

By default, the critters are oriented with their principal axes matching their current motion directions.

Except in the PickNPop game, there is always a distinguished critter called the player; this is usually represented as a small red triangle with a line indicating a gun, and with a circle around the triangle. If the player is dead or damaged, the filling of the triangle temporarily disappears. (Note that in Airhockey and in Worms the player has a different appearance.)

You normally move the player by using the Arrow keys, and you shoot the gun by pressing the spacebar. See the Keyboard and Mouse Controls section for more about the keyboard controls.

Some of the Pop games allow you to select different kinds of cursors, with the available cursors depending on the game. The cursors can act as tools that do things to the critters when you left-click. In particular if the Shoot, or Crosshairs, cursor is active, you can shoot by left-clicking the mouse.

If you prefer not to use the mouse button, or if you have a tracking device whose 'left-click' does not trigger the Pop program, you can press the Z key on your keyboard in place of left-clicking the mouse.

The games

The Pop program implements nine different games: Spacewar, PickNPop, Airhockey, Ballworld, Dambuilder, Worms, 2DStub, 3DStub, and Defender3D. The start-up game is the Spacewar game. Spacewar, PickNPop, Airhockey, and Defender3D are finished games. The others serve as starting points for games to program with the Pop Framework, or as demos of features of the framework.

All of the games except for 3DStub and Defender3D are essentially 2D. That is, in each of the games besides 3DStub and Defender3D, the critters are limited to move in fixed planes.

All of the games will take on a 3D appearance if you select View | 3D OpenGL Graphics. Critters that would be drawn as flat shapes are given a thickness for the 3D graphics mode.

    Part I: Software Engineering and Computer Games
    Part II: Software Engineering and Computer Games Reference