Example repo, showing the gist of how user-supplied wasm-functions can be created for the soulslike-routing project.
This example covers a deriveCurrentLocation function for Dark Souls: Remastered.
So called derive functions are supplied by the user when modeling a game. Certain kinds of state in the games are difficult or just impossible to just read from the games memory - They have to be derived from all kinds of different information, like combining parts of the model, current basic state and previous states.
To not overcomplicate the game-agnostic nature of the SLR-toolchain, I decided for now, that this kind of functions is to be supplied by the user in the form of small wasm functions when modeling the game.
On the other hand, since you are writing a derive function for a certain spec / model combination, you can and should get as specific as possible in your code, to squeeze out as much performance as possible!
To make interfacing with these kinds of functions, they have a pretty rigid interface you have to follow when writing them: At the moment, each function takes the same inputs, consisting of:
- The active spec
- The active model
- The state before this tick
- The state-updates we could already get in this tick.
The functions should then load and parse those objects if needed, compute the new state, which is probably always a foreign id (uuid) and then also store that in a Memory object, which is then returned to the javascript caller.