Make game object loading configurable

[punchcafe]

This ticket is a WIP

Motivation

Diving in to developing a game, when I want to create a new entity in the game, I have to create a model to represent it, set up listeners to make sure it is instantiated properly, manually set it to the physics manager etc... Realistically, I should be able to define a class which implements a Model interface, and then be able to create objects in TMX with the same type, and it should appear.

For example:

interface GameObjectModel<T> {
  void initialize(ModelConfig<T> someMap){ default imp }; // This would be injected from the values provided in tiled, and the method would have default behaviour for nulls.
}

Also, behaviour resolution between two objects should be handled without having to know about game objects. Something like:

interface BehaviourStrategy<SubjectType> {
  BiConsumer<SubjectType,Object> getBehaviourStrategy(Class anyClass){
    // returns the correct method for resolving collision
  }
}

Ideally, I feel like we don't need to ever handle game objects. This means we can build entire Java models, and everything else is abstracted away

[bitbrain]

I like the idea! I have reworded the ticket since we can make this very generic, however then use this e.g. in the TiledMapManager to load game objects based on a given configuration.

Currently, I am facing the same issue, where I manually need to decorate/initialise objects based on type (not very nice):

// AFTER tiledmap has been loaded
for (GameObject object : gameWorld.getObjects()) {
   if ("PLAYER".equals(object.getType()) {
      // initialise player here
   }
}

This approach is very cumbersome, error-prone and inflexible, since we have to do always changes in multiple places, check for types etc.

Instead, we can do the following:

1. implement a set of rules how game objects should be initialised
2. define objects and attributes e.g. in tiled
3. objects get automatically loaded and assigned to their e.g. behaviors etc.