start implementing area trace

src/geo/polygon.js

@@ -70,11 +70,15 @@ export class Polygon {
         return bounds;
     }
 
-    getBounds3D() {
-        let bounds = new THREE.Box3();
+    getBounds3D(bounds = new THREE.Box3()) {
         for (let point of this.points) {
             bounds.expandByPoint(point);
         }
+        if (this.inner) {
+            for (let i of this.inner) {
+                i.getBounds3D(bounds);
+            }
+        }
         return bounds;
     }