protected void computePosition() {

        float hDistance = (distance) * FastMath.sin((FastMath.PI / 2) - vRotation);
        pos.set(hDistance * FastMath.cos(rotation), (distance) * FastMath.sin(vRotation), hDistance * FastMath.sin(rotation));
        pos.addLocal(target.getWorldTranslation());
    }
Sets custom triggers for zooming out the cam
default is
new MouseAxisTrigger(MouseInput.AXIS_WHEEL, false)  mouse wheel down

@param triggers the triggers to assign
jme3-core/src/main/java/com/jme3/input/ChaseCamera.java