public static Vector3f computeTriangleNormal(Vector3f v1, Vector3f v2, Vector3f v3, Vector3f store) {
        if (store == null) {
            store = new Vector3f(v2);
        } else {
            store.set(v2);
        }

        store.subtractLocal(v1).crossLocal(v3.x - v1.x, v3.y - v1.y, v3.z - v1.z);
        return store.normalizeLocal();
    }
Alters the index of this triangle, used to identify it in an OBBTree.

@param index the desired index
jme3-core/src/main/java/com/jme3/math/Triangle.java