public void setRedArrow(Vector3f location, Vector3f extent) {
        arrowRedGeom.setLocalTranslation(location);
        arrowRed.setArrowExtent(extent);
    }
Alter the location and extent of the red arrow.

@param location the coordinates of the tail (not null, unaffected)
@param extent the offset of the tip from the tail (not null, unaffected)
jme3-jbullet/src/main/java/com/jme3/bullet/debug/DebugTools.java