fix selection reset

app/src/App.tsx

@@ -388,6 +388,11 @@ export default function App() {
 
 	// reduce selection, if selected points is reduced
 	useEffect(() => {
+		if (currentFrame.positions.length === 0) {
+			// this is not ideal, but we want to prohibit changes when loading
+			// one consequence is that the selection is not updated when the frame is empty
+			return; 
+		}
 		if (selectedIds.size > 0) {
 			const newSelectedIds = new Set(
 				Array.from(selectedIds).filter(

app/src/components/api.tsx

@@ -121,9 +121,12 @@ export function setupSelection(
 	selectedIds: Set<number>,
 ) {
 	const conInterfaceRef = useRef<any>(undefined);
-	const updateByRefreshRef = useRef(false);
+	const updateByRefreshRef = useRef(true);
 
 	useEffect(() => {
+		if (token === "") {
+			return;
+		}
 		console.log("setting up selection");
 		const con = new znsocket.Dict({
 			client: client,
@@ -134,6 +137,7 @@ export function setupSelection(
 		con.get("grp-0").then((items: any) => {
 			updateByRefreshRef.current = true;
 			setSelectedIds(new Set(items));
+			console.log("initial selection update to", items);
 		});
 
 		// External updates handler

app/src/components/particles.tsx

@@ -245,7 +245,9 @@ export const ParticleInstances = ({
 
 			// Mark instance matrices and colors for update
 			meshRef.current.instanceMatrix.needsUpdate = true;
-			meshRef.current.instanceColor.needsUpdate = true;
+			if (meshRef.current.instanceColor) {
+				meshRef.current.instanceColor.needsUpdate = true;
+			}
 		}
 	}, [
 		positions,

app/src/components/particlesEditor.tsx

@@ -5,6 +5,9 @@ import { socket } from "../socket";
 
 export const getCentroid = (positions: Vector3[], selection: Set<number>) => {
 	const centroid = new Vector3();
+	if (!positions || positions.length === 0) {
+		return centroid;
+	}
 	if (selection.size > 0) {
 		selection.forEach((i) => {
 			centroid.add(positions[i]);