How to Utilize Update in Unity

The Update function in Unity is a built-in function that is called once per frame and is commonly used to update the state of game objects and perform other game logic. Below are a few tips on how to properly utilize the Update function in the Unity code.

1. 'Time.deltaTime'

Since Update functions are called once per frame, it's important to use 'Time.deltaTime' to ensure that the updates are frame-rate independent. This means that the updates will execute at the same rate regardless of the frame rate, ensuring that the game behaves consistently across different hardware.

For example, to move an object at a constant speed, the movement vector needs to be multiplied by the 'Time.deltaTime' to ensure that the object moves at the same speed regardless of the frame rate:

void Update() {
    transform.position += Vector3.forward * speed * Time.deltaTime;
}

2. Avoid Expensive Calculations

As mentioned previously, since the Update is called once per frame, it's important to avoid performing expensive calculations that could impact performance. For example, if there is a complex algorithm that takes a long time to execute, it might be better to move it to a separate thread or break it up into smaller chunks that can be executed over multiple frames.

3. Use FixedUpdate for Physics

When working with physics in the game, it's recommended to use the FixedUpdate function instead of Update. FixedUpdate is called at a fixed rate, which is determined by the physics time step, and is designed to handle physics calculations like collision detection and rigid body movement. Using FixedUpdate for physics calculations can help ensure that the game physics behaves consistently and accurately across different frame rates.

4. Consider Using Coroutines

To perform an update that isn't tied to the frame rate, it might be better to use a Coroutine instead of an Update. Coroutines provide the functionality to pause the execution of a function for a specified amount of time, subsequently allowing it to perform time-based updates like spawning enemies or delaying an animation.

IEnumerator SpawnEnemy() {
    while (true) {
        Instantiate(enemyPrefab, spawnPoint.position, Quaternion.identity);
        yield return new WaitForSeconds(spawnDelay);
    }
}

To start a Coroutine simply call StartCoroutine once, like this:

StartCoroutine(SpawnEnemy());

To stop a Coroutine, use the StopCoroutine method which takes a reference to a Coroutine, IEnumerator, or a method name (Storing a reference from a StartCoroutine and using that to stop is a preferable approach since it knows exactly which instance of a Coroutine to stop):

Coroutine a = StartCoroutine(SpawnEnemy());

StopCoroutine(a);

Conclusion

Following these best practices will ensure that the Update functions are properly utilized in the Unity scripts.