What a game gives Cauldron2D.World to run: a pure value and the callbacks that change it.
defmodule MyGame do
@behaviour Cauldron2D.Game
def init(opts), do: ...
def join(state, player_id, props), do: {:ok, state}
def leave(state, player_id), do: state
def handle_input(state, player_id, %{held: held, aim: aim}), do: state
def step(state, dt), do: state
def view(state, player_id), do: ...
def drain_events(state), do: {events, state}
endEvery callback is pure. step/2 is called once per fixed tick with dt in seconds;
handle_input/3 before the tick for each player whose input changed; view/2 after it
for each player, and what it returns is sent to that player; drain_events/1 after it,
once, and the events go to every player. Nothing here reads a clock, and a game built
with the same options and given the same calls in the same order runs identically.
join/3's props are the game's to define. The clients in the cauldron_2d_*
packages pass :username (the player's name as a string) and whatever the game's own
join_props callback adds; a game that wants teams, spectators or anything else names
those props itself and reads them here.
Summary
Types
A player's input: Cauldron2D.Input.state/1's map, which a client looking through an
eye adds :heading to — where the player looks, in radians with 0 along +x — so
a game can walk :up along it, :down against it and :left and :right across it.
Types
@type input() :: %{ :held => MapSet.t(atom()), :aim => {number(), number()} | nil, optional(:strength) => %{required(atom()) => float()}, optional(:heading) => float() }
A player's input: Cauldron2D.Input.state/1's map, which a client looking through an
eye adds :heading to — where the player looks, in radians with 0 along +x — so
a game can walk :up along it, :down against it and :left and :right across it.
@type player_id() :: term()
@type state() :: term()