💡 Tip: Use Workers with onGameTick

[mertushka]

💭 Context

Node.js uses a single-threaded, event-driven architecture. That means everything in your onGameTick, event handlers, and custom logic runs on the same thread as the Haxball game engine.

If your code in onGameTick becomes computationally expensive (analytics, or complex decision logic), you can block the main thread and cause frame delay or lag.

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✅ Solution: Use Workers to offload computation

Node.js provides the worker_threads module to let you run CPU-heavy logic in a separate thread.

Instead of doing all your processing inside onGameTick, send just the necessary data (player position, ball position, etc.) to a Worker. This keeps the game loop responsive while still allowing complex logic to run in parallel.

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🧪 Example: Detecting proximity to the ball

This example shows how to send data from onGameTick to a worker thread that checks if the player is close to the ball.

room.js (Main Thread)

import { Worker } from "worker_threads";
const tickWorker = new Worker("./tickWorker.js");

room.onGameTick = function () {
  const players = room.getPlayerList();
  if (players.length === 0) return;
  const ball = room.getBallPosition();

  for (const player of players) {
    if (!player.position) continue;
    tickWorker.postMessage({
      player,
      ball,
    });
  }
};

tickWorker.on("message", (message) => {
  // Handle messages from the worker thread
  if (message.type === "proximityAlert") {
    const { playerName, playerId } = message;
    room.sendAnnouncement(
      `@${playerName}, you are close to the ball!`,
      playerId,
      0x00ff00,
      "bold",
      2
    );
  }
});

tickWorker.js (Worker Thread)

import { parentPort } from "worker_threads";

parentPort.on("message", (data) => {
  const { player, ball } = data;
  if (!player?.position || !ball) return;

  const dx = player.position.x - ball.x;
  const dy = player.position.y - ball.y;
  const distance = Math.sqrt(dx * dx + dy * dy);

  if (distance < 50) {
    parentPort.postMessage({
      type: "proximityAlert",
      playerName: player.name,
      playerId: player.id,
    });
  }
});