HistoryTracker and the Back button - studioplaynl/ARTWORLD_client GitHub Wiki

Locations and Homes

There are two types of scenes that players can enter: locations and homes. In cases when it is a location, this.location contains the scene name, while for a home, it contains the home's unique ID.

History Tracker

The class of History Tracker has two methods: locationPush and homePush. As the names suggest, when a player enters a location, a value of that location is pushed to the array of ManageSession.locationHistory, and when one gets into a home, an object with two properties is pushed to the same array:

{ locationName: "DefaultUserHome", homeID: scene.location }

Both methods have a condition, they should not be matching the value of the previous scene. Otherwise, a player gets into an infinite loop when using the back button.

Back button

On clicking of the back button, the last element of the array of ManageSession.locationHistory is taken in order to leave the current scene and stop the current scene:

let currentLocationKey = ManageSession.locationHistory.pop()
...
ManageSession.socket.rpc("leave", currentLocationKey)
...
this.scene.stop(currentLocationKey)

But before leaving the scene, we check whether the scene is a location or a house:

if (currentLocationKey.locationName && currentLocationKey.homeID) {
  currentLocationKey = currentLocationKey.locationName
}

if it is a house, then we reassign the value of the currentLocationKey.

And for entering the previous scene, we take the last element of the array of ManageSession.locationHistory and join it:

let previousLocation = ManageSession.locationHistory[ManageSession.locationHistory.length - 1]
...
ManageSession.getStreamUsers("join", previousLocation)

We also check whether the previous scene is a location or a house:

let homeID = null
if (previousLocation.locationName && previousLocation.homeID) {
  homeID = previousLocation.homeID
  previousLocation = previousLocation.locationName
}

For starting the previous scene, we provide two arguments, and the second argument is ignored when the scene is a location, not a home.

this.scene.start(previousLocation, { user_id: homeID })