three.js/src/extras/GeometryUtils.js

/**
 * @author mrdoob / http://mrdoob.com/
 */

THREE.GeometryUtils = {

	merge: function ( geometry1, geometry2, materialIndexOffset ) {

		THREE.warn( 'THREE.GeometryUtils: .merge() has been moved to Geometry. Use geometry.merge( geometry2, matrix, materialIndexOffset ) instead.' );

		var matrix;

		if ( geometry2 instanceof THREE.Mesh ) {

			geometry2.matrixAutoUpdate && geometry2.updateMatrix();

			matrix = geometry2.matrix;
			geometry2 = geometry2.geometry;

		}

		geometry1.merge( geometry2, matrix, materialIndexOffset );

	},

	center: function ( geometry ) {

		THREE.warn( 'THREE.GeometryUtils: .center() has been moved to Geometry. Use geometry.center() instead.' );
		return geometry.center();

	}

};