Killer Game Programming in Java

Controlling the Touring Sprite

The TouristControls object responds to key presses by moving the robot sprite or by changing the user's viewpoint. As the sprite moves, the viewpoint is automatically adjusted so the sprite and viewpoint stay a fixed distance apart. This is a simple form of third-person camera.

What's a Third-Person Camera?

A third-person camera is a viewpoint that semiautomatically or automatically tracks the user's sprite as it moves through a game. This is difficult to automate since the best vantage point for a camera depends on the sprite's position and orientation and on the location of nearby scenery and other sprites, as well as the focal point for the current action. A common solution is to offer the player a selection of several cameras.

Tour3D is simpler: the camera stays at a certain distance from the sprite, offset along the positive z-axis. This distance is maintained as the sprite moves forward, backward, left, and right. The only permitted adjustment to the camera is a zoom capability that reduces or increases the offset. Though this approach is simple, it is quite effective. The coding can be extended to support more complex changes in the camera's position and orientation.

Tip

As an added bonus, having a camera means that I no longer need to use Java 3D's OrbitBehavior class.

Setting Up TouristControls

The TourSprite and TouristControls are created and linked inside addTourist() in WrapTour3D :

 private void addTourist() { bob = new TourSprite("Coolrobo.3ds", ...