setFromMatrix4( m ) {

		const me = m.elements;

		this.set(

			me[ 0 ], me[ 4 ], me[ 8 ],
			me[ 1 ], me[ 5 ], me[ 9 ],
			me[ 2 ], me[ 6 ], me[ 10 ]

		);

		return this;

	}
Set this matrix to the upper 3x3 matrix of the given 4x4 matrix.

@param {Matrix4} m - The 4x4 matrix.
@return {Matrix3} A reference to this matrix.