three.js/examples/js/modifiers/ExplodeModifier.js

/**
 * Make all faces use unique vertices
 * so that each face can be separated from others
 *
 * @author alteredq / http://alteredqualia.com/
 */

THREE.ExplodeModifier = function () {

};

THREE.ExplodeModifier.prototype.modify = function ( geometry ) {

	var vertices = [];

	for ( var i = 0, il = geometry.faces.length; i < il; i ++ ) {

		var n = vertices.length;

		var face = geometry.faces[ i ];

		if ( face instanceof THREE.Face4 ) {

			var a = face.a;
			var b = face.b;
			var c = face.c;
			var d = face.d;

			var va = geometry.vertices[ a ];
			var vb = geometry.vertices[ b ];
			var vc = geometry.vertices[ c ];
			var vd = geometry.vertices[ d ];

			vertices.push( va.clone() );
			vertices.push( vb.clone() );
			vertices.push( vc.clone() );
			vertices.push( vd.clone() );

			face.a = n;
			face.b = n + 1;
			face.c = n + 2;
			face.d = n + 3;

		} else {

			var a = face.a;
			var b = face.b;
			var c = face.c;

			var va = geometry.vertices[ a ];
			var vb = geometry.vertices[ b ];
			var vc = geometry.vertices[ c ];

			vertices.push( va.clone() );
			vertices.push( vb.clone() );
			vertices.push( vc.clone() );

			face.a = n;
			face.b = n + 1;
			face.c = n + 2;

		}

	}

	geometry.vertices = vertices;
	delete geometry.__tmpVertices;

}