public static Vector3f computeNormal(Vector3f v1, Vector3f v2, Vector3f v3) {
        Vector3f a1 = v1.subtract(v2);
        Vector3f a2 = v3.subtract(v2);
        return a2.crossLocal(a1).normalizeLocal();
    }
A method that computes normal for a triangle defined by three vertices.

@param v1 first vertex
@param v2 second vertex
@param v3 third vertex
@return a normal for the face
jme3-core/src/main/java/com/jme3/math/FastMath.java