public final void setDirection(Vector3f dir){
        direction.set(dir);
        if (!direction.isUnitVector()) {
            direction.normalizeLocal();
        }
    }
Sets the direction of the light.
<p>
Represents the direction the light is shining.
(1, 0, 0) would represent light shining in the +X direction.

@param dir the direction of the light.
jme3-core/src/main/java/com/jme3/light/DirectionalLight.java