ActionTowerDefense/ActionTowerDefense/Assets/Scripts/Platform.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Platform : MonoBehaviour
{
    public Rigidbody rb;
    public List<Foot> feet = new List<Foot>();
    public float edgeDistance;

    public bool canDown;

    private void OnTriggerEnter(Collider other)
    {
        
        Foot foot = other.GetComponent<Foot>();
        if (foot != null && foot.transform.parent.gameObject.layer != 8)
        {
            if (Mathf.Abs(foot.transform.position.x - transform.position.x) > edgeDistance)
            {
                return;
            }
            foot.trigGroundList.Add(gameObject);
            feet.Add(foot);
        }
    }
    private void OnTriggerExit(Collider other)
    {
        Foot foot = other.GetComponent<Foot>();
        if(foot != null && foot.transform.parent.gameObject.layer != 8)
        {

            if(foot.trigGroundList.Exists(i =>i == gameObject))
            {
                foot.trigGroundList.Remove(gameObject);
            }
            if(feet.Exists(i => i == foot))
            {
                feet.Remove(foot);
            }
        }
    }
    private void OnDisable()
    {
        foreach(Foot i in feet)
        {
            if(i.trigGroundList.Exists(a => a == gameObject))
            {
                i.trigGroundList.Remove(gameObject);
            }
        }
    }
}