public void setNormal(Vector3f normal) {
        if (normal == null) {
            throw new IllegalArgumentException("normal cannot be null");
        }
        this.normal.set(normal);
    }
<code>setNormal</code> sets the normal of the plane.

@param normal
           the new normal of the plane.
jme3-core/src/main/java/com/jme3/math/Plane.java