Function clamp

Three.js/js/Three56.js:1889–1893

( x )

		// clamp, to handle numerical problems

		function clamp( x ) {

			return Math.min( Math.max( x, -1 ), 1 );

		}

		var te = m.elements;
		var m11 = te[0], m12 = te[4], m13 = te[8];