Input Handling

Input handling in the Client-Side Prediction (CSP) system is straightforward and flexible. The primary requirement is to implement the GetInput method, which captures user input and returns it in a structured format (e.g., a struct). This input is then used to simulate the entity's behavior during prediction.

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Key Concepts

1. Implementing GetInput:

   • The GetInput method is where you define how user input is captured and structured.

   • It returns an INPUT struct (e.g., SimpleWASDInput) that contains all relevant input data for the current frame.

   Example:

   protected override void GetFinalInput(ref Input input)
   {
       input.horizontal = Input.GetAxisRaw("Horizontal"),
       input.vertical = Input.GetAxisRaw("Vertical"),
       input.jump = Input.GetKey(KeyCode.Space),
       input.sprint = Input.GetKey(KeyCode.LeftShift)
   }

   • In this example, SimpleWASDInput is a struct that captures movement and action inputs.

2. Handling Key Down Events:

   • For key-down events (e.g., pressing a key once), you need to cache the input during Unity's Update method and clear the cache after returning it in GetInput.

   • This ensures that key-down events are properly registered and not skipped during simulation.

   Example:

   private bool _jumpKeyDown;
   
   private void Update()
   {
       // Cache key-down events in Unity's Update loop
       if (Input.GetKeyDown(KeyCode.Space))
           _jumpKeyDown = true;
   }
   
   protected override SimpleWASDInput GetFinalInput(SimpleWASDInput input)
   {
       input.horizontal = Input.GetAxisRaw("Horizontal"),
       input.vertical = Input.GetAxisRaw("Vertical"),
       input.jump = _jumpKeyDown,
       input.dash = Input.GetKey(KeyCode.LeftShift)
   
       // Clear the cached key-down event
       _jumpKeyDown = false;
   
       return input;
   }

   • Here, _jumpKeyDown is a cached variable that tracks whether the jump key was pressed during the current frame.

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Why This Works

• Flexibility:

  • The GetFinalInput method allows you to define exactly how input is captured and structured, making it adaptable to different control schemes.

• Key-Down Events:

  • By caching key-down events in Update and clearing them in GetFinalInput, you ensure that these events are only processed once, preventing unintended behavior (e.g., multiple jumps from a single key press).