Add grid; clipping plane

app/three/utils/utils.ts

@@ -0,0 +1,18 @@
+import { Vector3 } from "three";
+import { Extent } from "./build-scene";
+
+export function getMaxSize(extent: Extent) {
+  return Math.max(
+    extent.xmax - extent.xmin,
+    extent.ymax - extent.ymin,
+    extent.zmax - extent.zmin
+  );
+}
+
+export function getCenter3D(extent: Extent) {
+  return new Vector3(
+    (extent.xmin + extent.xmax) / 2,
+    (extent.ymin + extent.ymax) / 2,
+    (extent.zmax + extent.zmin) / 2
+  );
+}