How to Implement a Game Loop Without Freezing the UI Thread?

What is the best way to implement a game loop without freezing the UI thread?

// Example of a basic game loop structure in C# using Unity  
void Update()  
{  
    float deltaTime = Time.deltaTime;  
    ProcessInput();  
    UpdateGameLogic(deltaTime);  
    RenderGraphics();  
}

Implementing a game loop effectively means managing game updates and rendering while keeping the user interface (UI) responsive. A game loop is responsible for updating the game state and rendering graphics, and it’s crucial to ensure that this process does not block the main UI thread, leading to a frozen or unresponsive interface. This guide explores several techniques to achieve this, primarily focusing on multi-threading and graphics frameworks.

// Example of using async/await for background operations in C#  
private async void StartGame()  
{  
    await Task.Run(() => LoadResources());  
    StartGameLoop();  
}

Causes

• Blocking operations in the game loop.
• Heavy calculations or rendering in the main UI thread.
• Long-running tasks executed synchronously. 

Solutions

• Use asynchronous programming techniques, such as async/await in C# or Task in JavaScript, to offload heavy computations to background threads.
• Implement a separate thread for the game loop using frameworks like Unity, which has built-in support for updating and rendering without affecting UI responsiveness.
• Utilize timers or the requestAnimationFrame() function (in JavaScript) to ensure smooth frame updates without freezing the UI. In Unity, the Update() method runs consistently without freezing the UI.

Mistake: Running heavy calculations directly in the UI thread.

Solution: Always offload heavy processing to worker threads or use async methods to maintain UI fluidity.

Mistake: Neglecting to release GPU resources properly after rendering.

Solution: Ensure that any graphics resources are released to avoid memory issues and improve performance.

Mistake: Not utilizing appropriate synchronization methods for shared resources.

Solution: Use locks or concurrent collections when accessing shared data between threads to avoid race conditions.