I'm writing a component-based entity system and one of the components is the entity's state, which dictates how it reacts to game events. In case anyone has experience with implementing states, how granular should they be?
To give you an idea about how granular they are in my case, I have a WalkingLeft state and a WalkingRight state (as opposed to simply a Walking state) and I fear that they might be too granular. What do you think?
It should be as granular as you need the entities to be.
That means that if you don't ever have a case where an entity can walk to the left, but not to the right, you shouldn't split it up and just keep the "walking" component since anything else will just add unnecessary overhead.
And don't worry about how to find out what you're going to need in the future: The advantage of an component based model is that you can very easily exchange and split up small parts.
Always keep in mind: These kinds of architectures are not there to make your code look prettier, but to help you achieve what you want faster and more easily, plus less bug-prone. Splitting up walking to walking left and walking right if you don't ever need it has neither of the qualities above.
I'm writing a component-based entity system and one of the components is the entity's state
You have missed the point. In a component based system, the entity's state is parceled and distributed among different components, each of which has a well-defined and limited data storage and processing task. There is not one component that is "the state component".
As to how many you need, the only correct answer is exactly as many as you need to implement your game logic.
Entityhas a pointer to anEntityStateobject; that pointer can point to any implementation of the base state class.) \$\endgroup\$