three.js 3D平面到2D

Question

鉴于是3D空间中的THREE.Mesh实际上是一个平面：
Screenshot of Rooftop

几何的顶点例如是
[0] x = -9.364500045776367，y = -4.42410278320267，z = 7.22250041179359
[1] x = 2.948499954305589，y = -2.273284912108636，z = 4.937500411877409
[2] x = -7.154500045347959，y = 4.424102783203352，z = -8.842499588150531
[3] x = 2.412499954458326，y = -4.42410278320267，z = 8.842500411905348
[4] x = 9.364499954506755，y = 4.424102783203352，z = -6.5714995882008225
[5] x = 7.691499954555184，y = -2.273284912108636，z = 5.589500411879271

如何将3D坐标缩小为2D，以便可以在2D空间中绘制屋顶（添加矩形等）？

我尝试了什么：
像

一样旋转几何体

geometry2.rotateX( - geometry2.faces[0].normal.angleTo(  new THREE.Vector3(0,1,0)  ));
geometry2.rotateZ( - geometry2.faces[0].normal.angleTo(  new THREE.Vector3(0,1,0)  ));

不幸的是，仍然保持一个微小的角度，以便之后你的y坐标不相等。