修复自定义编号不显示，添加双面显示

src/Utils.ts

@@ -1,5 +1,12 @@
-import { Object3D, Mesh } from "three";
-import { createTemplateBoard, DrawDimension, Viewer } from ".";
+import { Object3D, Vector3 } from "three";
+import { DrawDimension, Viewer, createTemplateBoard } from ".";
+
+export const XAxis = new Vector3(1, 0, 0);
+export const XAxisN = new Vector3(-1, 0, 0);
+export const YAxis = new Vector3(0, 1, 0);
+export const YAxisN = new Vector3(0, -1, 0);
+export const ZAxis = new Vector3(0, 0, 1);
+export const ZAxisN = new Vector3(0, 0, -1);
 
 function dispose(m: Object3D)
 {