Workflow: Persistent data using a custom Storage entity


As a continuation from the post Workflow: Room loading with TMX, I’ve implemented one persistent data type called Storage to be able to demonstrate a workflow that will keep data between TMX loads.

Storage is an entity placed in Tiled (an Object). It is named s#. When the TMX is read, it instantiates a ‘storage’ Sprite onto the Board on its own ‘Storage’ z-layer.

It is then initialised: the Tiled property ‘name’ is copied to the C2 instance, and the room (my term for the currently processing TMX file) is also populated thus. (Unrelated, there is also a property called ‘content’ which is the initialising value for the Storage’s contents.)

After the Storage Sprite is initialised, it is effectively a TMX representation in C2. Now, I associate a Dictionary (named ‘StorageDict’) with this Storage Sprite. StorageDict has a ‘name’ and ‘room’ instance variable which are the two mandatory associations to match itself up with the Storage Sprite.

When a Storage Sprite is initialised it searches for its StorageDict partner using ‘name’ and ‘room’ instance variables. If it find it, then nothing needs to happen further — just making sure that there is actually a container for that storage. If it doesn’t find it, then it makes one. The only connection between a Storage Sprite and StorageDict is the ‘name’ and ‘room’ variables/properties.

When the TMX is unloaded and another reloaded, the StorageDict remain in memory. Loading and saving C2 will also keep the data. In other words, the association is ‘soft’.

EDIT: I’ve decided to directly relate the storage Sprite by adding an instance variable. This connection is always made every scene load, but it does save me from having to re-evaluate which StorageDict a storage Sprite is referring to.

Where to from here?

This demonstrate the use of a Dictionary to maintain C2 instance data. It is in itself the data and up this point there is no requirement to visually represent changes (eg tile id change based on a new value).

But I suppose this is where the next challenge is: changes in tile usage depending on saved data.


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