How to change fall delay of a gameobject by time? (C#, Unity)

[Bruce Ter]

First of all: sorry, if this website is not familiar with these kind of questions.

I want my gameobjects to fall faster by time as the player collides with them. What I mean is, when the game starts, the gameobjects fall off after 1 second the player collided with them, but after 60 seconds, gameobjects only fall after 0.3 seconds after the player has been collided with them.
The idea is to give the player less time to jump from a platform (gameobject) to another platform as the time goes, so it will be more challenging.
Here is what I've made so far:

    private Rigidbody rb;
    public float currentFallDelay = 1f;
    float minFallDelay = 0.3f;
    public float accelerationTime = 10;
    private float maxFallDelay;
    private float time;

    void Start()
    {
        rb = GetComponent<Rigidbody>();
        minFallDelay = currentFallDelay;
        time = 0;
    }

    public IEnumerator FallDelay()
    {
        rb.isKinematic = true;
        yield return new WaitForSeconds(1f);
        while (true)
        {
            currentFallDelay = Mathf.SmoothStep(minFallDelay, maxFallDelay, time / accelerationTime);
            transform.position += Vector3.down * currentFallDelay * Time.deltaTime;
            time += Time.deltaTime;
            yield return null;
        }
    }

    void OnCollisionEnter(Collision col)
    {

        if (rb.isKinematic && col.collider.CompareTag("Player"))
        {
            StartCoroutine(FallDelay());
        }

    }

I tried to use "yield return new WaitForSeconds(1f)" inside "FallDelay()" but of course it didn't change the fall delay after time.

Can anyone help me how to fix that?
Helps are appreciated!

[Stephan van Hulst]

Welcome to CodeRanch!

I'm not super familiar with Unity, but doesn't it have a built-in gravity simulator? You don't have to perform the transformation yourself. I think you just disable gravity for your platforms, and after a certain delay after you've touched the platform, you simply enable gravity for the platform and Unity will work its magic.

With that out of the way, how do you implement the fall delay? You need some sort of container that holds the current delay and that is accessible from your platforms. To do this, you can create a ScriptableObject class in your Assets directory that encapsulates your game state:

[CreateAssetMenu(menuName = "ScriptableObjects/FallDelay")]
public sealed class FallDelay : ScriptableObject
{
    [SerializeField]
    private float currentDelayInSeconds;

    [SerializeField]
    private float minDelayInSeconds;

    [SerializeField]
    private float maxDelayInSeconds;

    [SerializeField]
    private float decrementInSeconds;

    public float CurrentDelayInSeconds => currentDelayInSeconds;

    public bool IsMinimal => currentDelayInSeconds == minDelayInSeconds;

    public void DecreaseDelay()
    {
        currentDelayInSeconds -= decrementInSeconds;

        if (currentDelayInSeconds < minDelayInSeconds)
        {
            currentDelayInSeconds = minDelayInSeconds;
        }
    }

    public void ResetDelay()
    {
        currentDelayInSeconds = maxDelayInSeconds;
    }
}

In your inspector, create an instance of this asset from the right-click menu. You should be able to set initial values for the various properties of your new game object.

You can then use this game object from your platform behavior:

public sealed class Platform : MonoBehaviour
{
    [SerializeField]
    private RigidBody platform;

    [SerializeField]
    private FallDelay fallDelay;

    void OnCollisionEnter(Collision collision)
    {
        if (collision.collider.CompareTag("Player"))
        {
            StartCoroutine(FallAfterDelay());
        }
    }

    private IEnumerator FallAfterDelay()
    {
        yield return new WaitForSeconds(fallDelay.CurrentDelayInSeconds);
        platform.useGravity = true;
    }
}

So how and when do you call the DecreaseDelay() method? I recommend adding another object to your scene and adding a component to your object that periodically decreases the fall delay:

public sealed class DifficultyTimer : MonoBehaviour
{
    [SerializeField]
    private float periodInSeconds;

    [SerializeField]
    private FallDelay fallDelay;

    void Start()
    {
        StartCoroutine(DecreaseFallDelayPeriodically());
    }

    private IEnumerator DecreaseFallDelayPeriodically()
    {
        while (!fallDelay.IsMinimal)
        {
            yield return new WaitForSeconds(periodInSeconds);
            fallDelay.DecreaseDelay();
        }
    }
}