protected void vRotateCamera(float value) {
        if (!canRotate || !enabled) {
            return;
        }
        vRotating = true;
        float lastGoodRot = targetVRotation;
        targetVRotation += value * rotationSpeed;
        if (targetVRotation > maxVerticalRotation) {
            targetVRotation = lastGoodRot;
        }
        if (veryCloseRotation) {
            if ((targetVRotation < minVerticalRotation) && (targetDistance > (minDistance + 1.0f))) {
                targetVRotation = minVerticalRotation;
            } else if (targetVRotation < -FastMath.DEG_TO_RAD * 90) {
                targetVRotation = lastGoodRot;
            }
        } else {
            if ((targetVRotation < minVerticalRotation)) {
                targetVRotation = lastGoodRot;
            }
        }
    }
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