Trigger/Runtime/Collider/ColliderTriggerAreaBase.cs

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

namespace Syntriax.Modules.Trigger
{
    public abstract class ColliderTriggerAreaBase : MonoBehaviour, IColliderTriggerArea
    {
        protected Collider2D[] nonAllocResults = new Collider2D[32];
        protected int previousTriggerCount = 0;

        public LayerMask ColliderMask { get; set; } = ~0;
        public Action<List<Collider2D>> OnTriggeredCollidersUpdated { get; set; } = null;
        public List<Collider2D> ColliderList { get; protected set; } = new List<Collider2D>(32);

        protected abstract int TriggerCount { get; }

        public virtual bool Check()
        {
            int triggerCount = TriggerCount;

            if (triggerCount != previousTriggerCount)
            {
                ColliderList.Clear();
                for (int i = 0; i < triggerCount; i++)
                    ColliderList.Add(nonAllocResults[i]);

                OnTriggeredCollidersUpdated?.Invoke(ColliderList);
            }

            previousTriggerCount = triggerCount;
            return triggerCount > 0;
        }
    }
}