setRotationFromMatrix( m ) {

		// assumes the upper 3x3 of m is a pure rotation matrix (i.e, unscaled)

		this.quaternion.setFromRotationMatrix( m );

	}
Sets the given rotation represented as rotation matrix to the 3D object.

@param {Matrix4} m - Although a 4x4 matrix is expected, the upper 3x3 portion must be
a pure rotation matrix (i.e, unscaled).