[page:BufferGeometry] 的实例化版本。
默认构造函数没有参数。
继承属性详见 [page:BufferGeometry]。
默认值是 *Infinity*。
Read-only flag to check if a given object is of type [name].
继承方法详见 [page:BufferGeometry]。
Copies the given [name] to this instance.
[link:https://github.com/mrdoob/three.js/blob/master/src/[path].js src/[path].js]