解答：將 createCapsule 函數的 sphGeom 替換為：

var capsule = new THREE.Object3D();
capsule.add( cyl );
if ( !openTop || !openBottom ) {
	// instance geometry
	var sphGeom = new THREE.SphereGeometry( radius, segmentsWidth, segmentsWidth/2 );
	if ( !openTop ) {
		var sphTop = new THREE.Mesh( sphGeom, material );
		sphTop.position.set( top.x, top.y, top.z );
		capsule.add( sphTop );
	}
	if ( !openBottom ) {
		var sphBottom = new THREE.Mesh( sphGeom, material );
		sphBottom.position.set( bottom.x, bottom.y, bottom.z );
		capsule.add( sphBottom );
	}
}
return capsule;