Atom Engine

GameLoop

Purpose

GameLoop is a high-level wrapper around a low-level loop system. It encapsulates the creation and management of a game loop that repeatedly executes update and render functions at a fixed timestep. It simplifies starting, stopping, and querying the state of the loop.

Lifecycle

Creation → Update → Destruction

• Creation: A GameLoop instance is constructed with update and render callbacks. Internally, it initializes loop state via createLoop.
• Update: Once started, the loop repeatedly invokes the provided update(dt) and render(alpha) functions according to the underlying loop implementation.
• Destruction: The loop can be stopped via stop(), which halts execution. The instance itself does not explicitly release resources beyond stopping the loop.

Public API

• constructor(update, render, fixedDelta?)
  • update(dt: number): Function called each tick with delta time.
  • render(alpha: number): Function called for rendering interpolation.
  • fixedDelta?: number: Fixed timestep interval (default: 1/60).
• start(): void
  • Starts the internal loop execution.
• stop(): void
  • Stops the internal loop execution.
• isRunning(): boolean
  • Returns whether the loop is currently active.

Internal Behavior

• Maintains an internal LoopState object created by createLoop(update, render, fixedDelta).
• Delegates execution control to external loop utilities:
  • startLoop(state) begins the loop.
  • stopLoop(state) halts the loop.
• The state.running flag is used to determine whether the loop is active.
• The class itself does not implement timing logic; it acts as a thin orchestration layer over the loop system.

Example

const loop = new GameLoop(
  (dt) => {
    // update game logic
    console.log("update", dt);
  },
  (alpha) => {
    // render frame
    console.log("render", alpha);
  }
);

loop.start();

setTimeout(() => {
  console.log(loop.isRunning()); // true
  loop.stop();
}, 2000);

Related Elements

• LoopState
• createLoop
• startLoop
• stopLoop