public Matrix3f toRotationMatrix() {
        return new Matrix3f(m00, m01, m02, m10, m11, m12, m20, m21, m22);
    }
Determine the rotation component of this 3-D coordinate transform.

<p>If the transform includes scaling or reflection or shear, the result
might not be a valid rotation matrix.

@return a new Matrix3f
jme3-core/src/main/java/com/jme3/math/Matrix4f.java