如何在一定时间后不与 Unity 中的播放器 object 发生碰撞后使平台 go 下降？

Question

I'm new to Unity and C# in general, so excuse my terminology(or lack thereof)...

I have succeeded -with the help of a friend, to credit where its due- in making a platform go up a certain amount after one frame of collision with the player, The only problem is that, now. I can't seem to get it moving down again.., Said friend challenged me to make it go up, stay airborne for a certain amount of time. then go back down.

Here is a snippet of my working code that makes it go up.

bool HaveCollided = false; //Collision checker boolean

void Update()
    {
        Vector3 up = lifter * Time.deltaTime;
        if (HaveCollided != true || transform.position.y >= 5)
        {
            return;
        }
    }
void OnCollisionEnter(Collision collision) //Makes HaveCollided true at collision event
    {
        if (collision.gameObject.GetComponent<Playertag>() != null) //don't use GetComponent in Update()
        {
            HaveCollided = true;
        }

So if my logic is right, I'd need to nest another if statement inside the one where the condition is: HaveCollided.= true || transform.position.y >= 5 HaveCollided.= true || transform.position.y >= 5 which should be:

if (newTime == Time.deltaTime * CertainAmount && transform.position.y >= 1) //make platform go down until y position is equal to 1
        {
            //make platform go down
            Debug.Log("reached");
            transform.position = transform.position - up;
        }

But it's not working. It doesn't even seem to reach the part that would make the platform descend. I literally do not know where to go from here...

Answer 1

Based on your comment I made a few revisions to make the platform movement a bit smoother. I also made it so the same function can be used for both the upward and downward motion.

using UnityEngine;
using System.Collections;

[SerializeField] private float timeToMovePlatform = 0.0f;       // time it takes the platform to get from 1 point to another
[SerializeField] private float timeToRestAtPeak = 0.0f;         // time that the platform rests at the top of its movement
[SerializeField] private float platformYOffset = 0.0f;          // offset the platform moves from its origin point to float upward


private Coroutine movingPlatform = null;                         // determines if the platform is currently moving or not

private void OnCollisionEnter(Collision col)
{
    // add a tag to your player object as checking a tag at runtime vs. a GetComponent is faster
    if(col.gameObject.tag == "Player")
    {
        // only trigger when we are not currently moving
        if(movingPlatform == null)
        {
            // start our coroutine so the platform can move
            movingPlatform = StartCoroutine(MovePlatform(true));
        }
    }
}

/// <summary>
/// Moves this object up or down depending on the parameter passed in
/// </summary>
/// <param name="moveUpward">Determines if this object is currently moving upward or not</param>
private IEnumerator MovePlatform(bool moveUpward)
{
    // store our start position 
    Vector3 startPos = transform.position;
    
    // build our goal position based on which direction we are moving
    Vector3 goalPos = new Vector3(startPos.x, startPos + (moveUpward ? platformYOffset : -platformYOffset), startPos.z);
    
    // set our current time
    float currentTime = 0.0f;
    
    while(currentTime <= timeToMovePlatform)
    {
        // lerp the position over the current time compared to our total duration 
        transform.position = Vector3.Lerp(startPos, goalPos, currentTime / timeToMovePlatform); 
        
        // update our timer
        currentTime += Time.deltaTime;
        
        // need to yield out of our coroutine so it does not get stuck here
        yield return null;
    }
    
    // just in case there are any floating point issues, set our position directly
    transform.position = goalPosition;
    
    // when we are moving upward, make sure to stop at the peak for the set duration
    if(moveUpwards)
    {
        yield return WaitForSeconds(timeToRestAtPeak); 
        
        // once we are done waiting, we need to move back downward
        StartCoroutine(MovePlatform(false));
    }
    else
    {
        // we finished moving downward, so set our coroutine reference to false
        // so the player can set the platform to move again
        movingPlatform = null;
    }
}

Fair warning, I did not test this code it is more a direction I would take for your situation. Before doing anything, add a tag to your player. If you are unsure what tags are, check out the docs . Be sure to give the player the tag Player so that the code will work as expected.

You will notice the first three variables are Serialized but are private. By doing this, it allows for Unity to show them in the inspector but not allow other scripts to touch them.

To learn more about Coroutines, check out the docs and for Lerps, I enjoy this blog post . Let me know if this works for you and/or you have any questions.

Answer 2

Your best bet is to add colliders and use isTrigger. Seed a time and if it's not triggered within that time period raise an event.