Asynchronous game engine
Client-side JavaScript is non-blocking: all long-running operations are asynchronous. The ROT.Engine loop is well suited for orchestrating the possibly-async coordination of various game actors.
To control a game loop, you add individual entities (called actors) to the engine. Every entity must implement the getSpeed() method (since it is fed to the built-in scheduler and the act() method. Once the engine is started, it correctly calls the act() method on proper actors. It is possible to recursively stop (lock) the engine, should some operation (such as displaying a dialog or waiting for user input) block the execution. Once all lock levels are unlocked, the engine continues its execution.
var engine = new ROT.Engine();
var output = [];
/* sample actor: pauses the execution when dead */
var actor1 = {
getSpeed: function() { return 100; },
lives: 3,
act: function() {
output.push(".");
this.lives--;
if (!this.lives) {
engine.removeActor(actor1);
engine.lock(); /* pause execution */
setTimeout(unlock, 500); /* wait for 500ms */
}
}
}
engine.addActor(actor1);
var unlock = function() { /* called asynchronously */
var actor2 = {
getSpeed: function() { return 100; },
act: function() {
output.push("@");
engine.removeActor(actor2);
}
}
output = [];
engine.addActor(actor2); /* add second actor */
engine.unlock(); /* continue execution */
SHOW(output.join(""));
}
engine.start();
SHOW(output.join(""));