Killer Game Programming in Java

Animating the Sprite

Figure 19-6 shows the visible methods in Animator.

Animator performs three core tasks:

• It adds animation sequences to its schedule in response to calls from the KeyBehavior object.

• It periodically removes an animation operation from its schedule and executes it. The execution typically changes the sprite's position and pose. A removal is triggered by the arrival of a Java 3D WakeupOnElapsedTime event.

• It updates the user's viewpoint in response to calls from KeyBehavior.

Figure 19-6. Public methods in the Animator class

Adding an Animation Sequence

The majority of the public methods in Animator (rotClock(), rotCounterClock(), moveLeft(), moveRight(), punch(), moveForward(), moveBackwards(), and toggleAc-tive()) execute in a similar way when called by the KeyBehavior object. They add a predefined animation sequence to a schedule (which is implemented as an ArrayList called animSchedule):

    public void moveForward()
    { addAnims(forwards); }

forwards is an array of strings, which represents the animation sequence for moving the sprite forward one step:

    private final static String forwards[] = {"walk1", "walk2", "stand"};

"walk1", "walk2", and so forth are the names of the 3DS files holding the sprite's pose This correspondence is used to load the models when AnimTour3D starts.

A requirement of an animation sequence is that it ends with "stand". One reason for this is that ...