Saving Games

Godot Engine already has a tutorial about saving games here, but it may not be for everyone. Basically, it grabs all the nodes in the “Persist” group and writes them to a file. It does this line-by-line, but you might just want to dump a dictionary to a file and grab it again.

I'm assuming you are using a singleton (preload) scrip that holds the game data. Singletons are scripts that load before any others and can hold persistent data for the game. Dictionaries are a complex datatype that can keep things organized. Since dictionaries are passed by reference, they are easy to keep updated.

func save_world():
    var saveFile = File.new()
    saveFile.open("user://savegame.save", File.WRITE)
    saveDat["Cells"] = cells
    saveDat["VacDat"] = vacDat
    saveDat["PlayDat"] = playerDat
    saveDat["Storage"] = storeDat
    saveDat["MatDat"] = matDat
    saveDat["BuildDat"] = buildDat
    saveDat["RingDat"] = ringDat
    saveDat["WorldDat"] = worldDat
    saveFile.store_var(saveDat)
    saveFile.close()
   
    pass

 Everyone will tell you that you don't need the "pass" keyword. They are correct, "pass" is used to skip empty functions and does no harm at the bottom of a function. I usually start two or more functions at once and use pass so I don't get errors or red lines as I work on individual functions.

First I created the "saveFile" variable and created a new file. Then I opened a file I intended to save to. The file does not need to exist if you are writing it, godot will automatically create a new file. It is best to use the "user://" location as this is a location that the game is allowed to write to. Now I assign the different variables I want to save to a single variable I initialized at the top of the script. Then the variable is stored in the file and it is closed. Remember to close the file to avoid memory leaks.

func load_world():
    var saveFile = File.new()
    if not saveFile.file_exists("user://savegame.save"):
        print("error, no save file")
    else:
        saveFile.open("user://savegame.save", File.READ)
        saveDat = saveFile.get_var()
        cells = saveDat["Cells"]
        vacDat = saveDat["VacDat"]
        playerDat = saveDat["PlayDat"]
        storeDat = saveDat["Storage"]
        matDat = saveDat["MatDat"]
        buildDat = saveDat["BuildDat"]
        ringDat = saveDat["RingDat"]
        worldDat = saveDat["WorldDat"]
    saveFile.close()
   
    pass

Now to load the data back. First we need to create a variable and open a new file. Variables initialized in a function can only be used by that function. Next, check to make sure the file actually exists, since we are getting data from it. I don't check to see if the file has any data since it should be in there.

Open the file and assign the data to another variable, the one initialized at the top of the scrip should work. Now we just apply the different key values to their respective variables. I'm not sure if different keys are passed by reference, but I think it depends on the variable's type. Finally, close the file to prevent memory leaks.

Feel free to reference godot's save tutorial if you want to try different ways of saving data.