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Saving and Restoring State

Dialogue State

Every runtime dialogue has a set of active state which comprises 3 things:

  • The state of all variables
  • The current speaker line
  • The set of choices which have been taken before

If you want dialogue state to persist between times when the dialogue instance itself doesn't - either if you dispose of your dialogue instances once the UI closes, or across save games, you need access to that state so you can store it somewhere, and include it in your save game.

BP_SudsProDialogueRunner does it for you!

When using BP_SudsProDialogueRunner, dialogue state is automatically saved in its DialogueState property, and if you run this dialogue again, state will be restored. The DialogueState property is marked SaveGame so it will be stored in save games as well (depending on how you save your games).

If you'd prefer to run your dialogue another way, or are just curious about how the state is being saved by BP_SudsProDialogueRunner, read on.

Extracting Dialogue State

To get a snapshot of dialogue state, call GetSavedState on the dialogue instance. You could just save this in a property on the owner of the dialogue, for example:

Get Dialogue State

If you mark this property "Save Game", then most save game systems (such as SPUD) will be able to serialise it along with the rest of your save game data.

Restoring Dialogue State

When you run the dialogue, instead of just immediately starting it, call RestoreSavedState first, like this:

Restore Dialogue State

RestoreSavedState will restore the active speaker node as well, in case you saved in the middle of the dialogue.

Examining Dialogue State

If you want you can dig into the dialogue state:

Dialogue State Detail

It contains:

  • Variables A map of variables by name

  • Choices Taken: The set of choices that have been picked before (e.g. so you can mark choices the player has already taken)

  • Text Node ID: this is the speaker line which the dialogue was on when the state was retrieved.

It's important to note that Text Node ID and the Choices Taken use the String Keys associated with the speaker line or choice, which are also used for Localisation.

These identifiers are usually generated at import time, but will only be constant through later edits of the script if those IDs are added back to the script itself. These IDs do clutter the script so it's nicer to omit them while going through writing and editing cycles.

It's best not to rely on saving mid-dialogue or having reliable choice highlighting across save games while your dialogue is in active development, until you get to the point when your script is mostly finished, and you're ready to localise it.

Global State

You may also be using global variables, and want to save the state of those variables.

To do so, get a reference to the SUDSSubsystem and use the same kind of functions as dialogues, but the Global versions, e.g. GetSavedGlobalState, RestoreSavedGlobalState.

Using SPUD

One of the easiest ways to handle saved dialogue in save games is via one of my other projects, SPUD.

Dialogue State

Assuming that you've made the owner of the dialogue the NPC you're talking to, and that NPC is already registered as a SPUD Object, simply having a property marked as "Save Game" with the dialogue state from GetSavedState in it will automatically save that state too.

You still need to populate it by calling GetSavedState, which you can either do at the end of the dialogue (if the NPC is a Participant this is easy, use the OnDialogueFinished callback), or if you can save mid-dialogue then use the ISPUDObjectCallback::SpudPreStore hook.

Global State

Global state will need to be stored in a SaveGame property of a UObject which is registered with SPUD via AddPersistentGlobalObjectWithName. You can extract the state from SUDS using SUDSSubsystem's GetSavedGlobalState method, and restore it after load using RestoreSavedGlobalState.


See Also