Add a night cycle

Goal

The adventure gets a clock: two minutes of day, thirty seconds of night, over and over. At dusk and at dawn every player hears it, the room list shows the room as day or night, and while it is dark the chests and the door stay shut. The lengths are rules, so tuning them is a number in src/game.ts.

This is the survive kit's clock (templates/survive/src/systems/clock.ts) without the creatures. It works alone and in a room; with Play with friends done, the room's authority keeps the time for everyone.

Files you will edit

• src/game.ts

Steps

1. Add the two lengths to rules in defineGame, beside the others.

   rules: {
     // ...the rules already there
     daySeconds: 120,
     nightSeconds: 30,
   },

2. Keep the clock at module scope, below the imports. It is two fields, made once, so the system below allocates nothing. Module state is frozen into the wasm guest at build time, so init resets it (step 4).

   /** Day or night, and `ctx.elapsed` when this one began. */
   const sky = { night: false, since: 0 };

3. Turn the clock on the authority. A guest with no room (the solo role) runs it too, so the adventure alone has nights as well. ctx.net.setPhase sends only when the word changes, so saying it every step costs nothing; a guest with no room ignores it.

   /** Authority: day to night and back, said to every player and the room list. */
   function nightCycle(ctx: GameContext): void {
     const length = Number(sky.night ? ctx.rules.nightSeconds : ctx.rules.daySeconds);
     if (ctx.elapsed - sky.since >= length) {
       sky.night = !sky.night;
       sky.since = ctx.elapsed;
       ctx.net.send(sky.night ? 'dusk' : 'dawn', null);
     }
     ctx.net.setPhase(sky.night ? 'night' : 'day');
   }
   
   /** Client: hear dusk and dawn. Alone, the authority is this page. */
   function hearTheSky(ctx: GameContext): void {
     if (ctx.net.role === 'solo') return;
     if (ctx.net.messages('dusk').length > 0) ctx.audio.play('sfx.door');
     if (ctx.net.messages('dawn').length > 0) ctx.audio.play('sfx.key');
   }
   
   /** The interact system, by day only: nothing opens in the dark. */
   function byDay(ctx: GameContext): void {
     if (!sky.night) interactSystem(ctx);
   }

4. Reset it in init, beside the resets already there.

   init: (ctx) => {
     sky.night = false;
     sky.since = 0;
     // ...the resets already there
   },

5. Wire it in systems. The clock first, so dusk takes effect in the same step; byDay in place of interactSystem; the sound on each page.

   systems: [
     nightCycle,
     paintPlayers,
     locomotionSystem,
     byDay,
     dialogueSystem,
     updateHud,
     { run: hearTheSky, on: 'client' },
   ],

   With multiplayer declared, a bare function runs on the authority, so nightCycle and byDay decide for the whole room; without it, the one page runs everything.

Verify

npm test
npm run dev

The tests still pass: each one plays well under two minutes, so it never gets dark. In the page, open a chest within the first two minutes: it opens. Wait for dusk (the door sound in a room), and E at the other chest does nothing until dawn, thirty seconds later. In a room, the Browse rooms list shows the room as day or night. For a quick look, set daySeconds: 10 and restart.

See also

• Add a lobby: the same wrapper idea, holding systems back until the start
• Send a message: send and messages on their own
• Multiplayer: roles, ctx.net.setPhase, and what a client may do
• templates/survive/src/systems/clock.ts: the same clock, with creatures at dusk and a night count at dawn