一、geometry=>buffergeomerty
var bufferGeometry = new THREE.BufferGeometry().fromGeometry( geometry );
threejs官方文档:https://threejs.org/docs/index.html#api/en/core/BufferGeometry.fromGeometry
二,计算Tangents
threejs官方文档:https://threejs.org/docs/index.html#examples/utils/BufferGeometryUtils