Saving and restoringpreview
How the player saves a game, what a save contains, and what your actor must do for restores to work.
The player saves the complete state of every game actor. You don't write save or load code: whatever is in your actor's variables when the game is saved is there when it's restored.
Save and restore#
moxzi-player out/drift native --save drift.saveThe player writes the save periodically, when the app goes to the background, and when it exits. Start from a save with --restore:
moxzi-player out/drift native --restore drift.savemoxzi-game inspect-checkpoint FILE prints a summary of a save: its tick, the number of actors, and their memory size.
New game#
Players with a saved game see Save and New game buttons. New game asks for confirmation, then starts your game from moxzi_boot with a fresh actor. The previous save is kept as a backup until the next successful save.
What your actor must do#
Because the save is the actor's whole state, most games need no extra work. A few rules keep restores working:
| Rule | Why |
|---|---|
Store the time of the last tick and pass it to Render.empty in moxzi_snapshot | The player checks that the restored scene matches the restored clock. A mismatch stops the player with lifecycle acknowledgement disconnected |
| Keep everything that affects the game in actor variables | Anything else, such as values derived from the wall clock, won't be restored |
Rebuild the full scene in moxzi_snapshot from the current state | After a restore the player calls it to draw the first frame |
Sounds, the camera view the player has moved, and panel settings are not part of the save.
Compatibility#
A save can only be restored by the exact package that wrote it, on the same execution backend (native, pulley or aot). Rebuild your game and old saves are refused with an error; they aren't converted. Use a new save file for each build while developing.
Limitations#
| Limitation | What to do |
|---|---|
| Saves can't be migrated to a new build | Plan to start new games after an update |
| Save files are limited to 128 MiB | Keep large, rebuildable data out of actor state |