修复autocad显示错误

src/SimpleBoard.ts

@@ -89,8 +89,8 @@ export class SimpleBoard
 
             pts.push(new Vector2(0, 0),
                 new Vector2(this.width, 0),
-                new Vector2(this.width, length),
-                new Vector2(0, length),
+                new Vector2(this.width, this.height),
+                new Vector2(0, this.height),
                 new Vector2(0, 0)
             );
             buls.push(0, 0, 0, 0, 0);
@@ -154,7 +154,7 @@ export class SimpleBoard
         mesh.userData = ext.Normal;
         edges.forEach(e => e.userData = ext.Normal);
         // 自定义编号
-        if (this._CustomNumber)
+        if (this._CustomNumber && this._CustomNumber.length > 0)
         {
             mesh.add(this.createCustomNo());
         }