public void setXExtent(float xExtent) {
        if (xExtent < 0) {
            throw new IllegalArgumentException();
        }

        this.xExtent = xExtent;
    }
Alter the X-axis distance between the center and the boundary.

@param xExtent the desired distance (&ge;0)
jme3-core/src/main/java/com/jme3/bounding/BoundingBox.java