bitECS: Fix rotation with Object menu

This PR fixes roation operation with the Object menu.

**Problem**

Rotation focus is not released even if releasing mouse click
if you release the space bar earlier than mouse click release.

The root issue is heldExitQuery for handling mouse click release
is not called if ObjectMenu.targetRef[menu] is not set.

Then if ObjectMenu.targetRef[menu] is cleared by releasing the
space bar earlier than releasing mouse click, heldExitQuery
won't be called.

**Solution**

Always call heldExitQuery.

**Changes**

- Always call heldExitQuery
- Save rotation/scale taget entity id when the operaton starts
  because rotation/scale are operated by dragging so that
  the operations can continue even if the cursor hovers off
  the target entity
- Use the saved target entity id when the operation ends

src/bit-systems/object-menu.ts

@@ -32,6 +32,13 @@ const _mat4 = new Matrix4();
 
 let scalingHandler: ScalingHandler | null = null;
 
+// Needs to remember rotating/scaling entity id because
+// rotation/scaling are operated by dragging so that
+// rotation/scaling operation can continue even if the cursor
+// hover off the target entity.
+// TODO: Should this data stored in Component?
+let handlingTargetEid: EntityID = 0;
+
 function clicked(world: HubsWorld, eid: EntityID) {
   return hasComponent(world, Interacted, eid);
 }
@@ -94,14 +101,21 @@ function startRotation(world: HubsWorld, targetEid: EntityID) {
   transformSystem.startTransform(world.eid2obj.get(targetEid)!, world.eid2obj.get(rightCursorEid)!, {
     mode: TRANSFORM_MODE.CURSOR
   });
+  handlingTargetEid = targetEid;
 }
 
-function stopRotation(world: HubsWorld, targetEid: EntityID) {
-  if (hasComponent(world, Networked, targetEid)) {
-    addComponent(world, EntityStateDirty, targetEid);
+function stopRotation(world: HubsWorld) {
+  // TODO: More proper handling in case the target entity is already removed.
+  //       In the worst scenario the entity has been already recycled at this moment
+  //       and this code doesn't handled such a case correctly.
+  //       We may refactor when we will reimplement the object menu system
+  //       by removing A-Frame dependency.
+  if (entityExists(world, handlingTargetEid) && hasComponent(world, Networked, handlingTargetEid)) {
+    addComponent(world, EntityStateDirty, handlingTargetEid);
   }
   const transformSystem = APP.scene!.systems["transform-selected-object"];
   transformSystem.stopTransform();
+  handlingTargetEid = 0;
 }
 
 function startScaling(world: HubsWorld, targetEid: EntityID) {
@@ -117,15 +131,17 @@ function startScaling(world: HubsWorld, targetEid: EntityID) {
   scalingHandler = new ScalingHandler(world.eid2obj.get(targetEid), transformSystem);
   scalingHandler!.objectToScale = world.eid2obj.get(targetEid);
   scalingHandler!.startScaling(world.eid2obj.get(rightCursorEid));
+  handlingTargetEid = targetEid;
 }
 
-function stopScaling(world: HubsWorld, targetEid: EntityID) {
-  if (hasComponent(world, Networked, targetEid)) {
-    addComponent(world, EntityStateDirty, targetEid);
+function stopScaling(world: HubsWorld) {
+  if (entityExists(world, handlingTargetEid) && hasComponent(world, Networked, handlingTargetEid)) {
+    addComponent(world, EntityStateDirty, handlingTargetEid);
   }
   const rightCursorEid = anyEntityWith(world, RemoteRight)!;
   scalingHandler!.endScaling(world.eid2obj.get(rightCursorEid));
   scalingHandler = null;
+  handlingTargetEid = 0;
 }
 
 function openLink(world: HubsWorld, eid: EntityID) {
@@ -203,10 +219,10 @@ function handleHeldEnter(world: HubsWorld, eid: EntityID, menuEid: EntityID) {
 function handleHeldExit(world: HubsWorld, eid: EntityID, menuEid: EntityID) {
   switch (eid) {
     case ObjectMenu.rotateButtonRef[menuEid]:
-      stopRotation(world, ObjectMenu.targetRef[menuEid]);
+      stopRotation(world);
       break;
     case ObjectMenu.scaleButtonRef[menuEid]:
-      stopScaling(world, ObjectMenu.targetRef[menuEid]);
+      stopScaling(world);
       break;
   }
 }
@@ -253,14 +269,15 @@ const heldExitQuery = exitQuery(heldQuery);
 export function objectMenuSystem(world: HubsWorld, sceneIsFrozen: boolean, hubChannel: HubChannel) {
   const menu = anyEntityWith(world, ObjectMenu)!;
 
+  heldExitQuery(world).forEach(eid => {
+    handleHeldExit(world, eid, menu);
+  });
+
   ObjectMenu.targetRef[menu] = objectMenuTarget(world, menu, sceneIsFrozen);
+
   if (ObjectMenu.targetRef[menu]) {
     handleClicks(world, menu, hubChannel);
 
-    heldExitQuery(world).forEach(eid => {
-      handleHeldExit(world, eid, menu);
-    });
-
     heldEnterQuery(world).forEach(eid => {
       handleHeldEnter(world, eid, menu);
     });