OldBlueWater/BlueWater/Assets/02.Scripts/Arrow.cs

using System.Collections;
using UnityEngine;
using UnityEngine.Pool;
using Random = UnityEngine.Random;

// ReSharper disable once CheckNamespace
namespace BlueWaterProject
{
    public class Arrow : MonoBehaviour
    {
        #region Property and variable

        [Tooltip("화살 발사 시작할 때의 속도")]
        [SerializeField] private float initialVelocity;
        
        [Tooltip("화살이 타겟에 도달하는 오차 범위(부정확함)")]
        [Range(0f, 1f)]
        [SerializeField] private float inaccuracy;
        
        [Tooltip("발사 이후 자동으로 사라지는데 까지 걸리는 시간")]
        [Range(0f, 10f)]
        [SerializeField] private float autoDestroyTime;

        private Vector3 targetPos;
        private AiStat attackerStat;
        private LayerMask targetLayer;
        private IObjectPool<Arrow> managedArrowPool;
        private Rigidbody arrowRigidbody;

        #endregion

        #region Unity built-in function

        private void Awake()
        {
            arrowRigidbody = Utils.GetComponentAndAssert<Rigidbody>(transform);
        }

        private void OnTriggerEnter(Collider other)
        {
            if (other.gameObject.layer != targetLayer) return;

            var iDamageable = other.GetComponent<IDamageable>();
            
            iDamageable.TakeDamage(attackerStat, iDamageable.AiStat);
        }

        #endregion
        
        #region Custom function

        public IEnumerator Shoot()
        {
            // TODO : 화살 발사 기능 구현
            var time = 0f;
            
            while (time < autoDestroyTime)
            {
                time += Time.deltaTime;

                var toTarget = targetPos - transform.position;
                var angle = CalcLaunchAngle(toTarget);

                angle += Random.Range(-inaccuracy, inaccuracy);
                
                var velocity = Quaternion.Euler(0, 0, angle) * Vector3.right * initialVelocity;

                arrowRigidbody.velocity = velocity;

                yield return null;
            }

            DestroyObject();
        }
        
        private float CalcLaunchAngle(Vector3 toTarget)
        {
            var distance = Vector3.Distance(toTarget, Vector3.zero);
            var heightDifference = toTarget.y;

            var gravity = Physics.gravity.magnitude;
            var velocitySqr = initialVelocity * initialVelocity;
            var underSqrt = (velocitySqr * velocitySqr) - (gravity * ((gravity * distance * distance) + (2 * heightDifference * velocitySqr)));
            
            if (underSqrt >= 0)
            {
                var angle1 = Mathf.Atan((velocitySqr + Mathf.Sqrt(underSqrt)) / (gravity * distance));
                var angle2 = Mathf.Atan((velocitySqr - Mathf.Sqrt(underSqrt)) / (gravity * distance));
                
                return Mathf.Min(angle1, angle2) * Mathf.Rad2Deg;
            }
            else
            {
                return 45f;
            }
        }

        public void SetShootingArrow(Vector3 targetPosition, AiStat attacker, int targetLayerMask)
        {
            targetPos = targetPosition;
            attackerStat = attacker;
            targetLayer = targetLayerMask;
        }
        //public void SetAiStat(AiStat attacker) => attackerStat = attacker;
        //public void SetTargetLayer(int targetLayerMask) => targetLayer = targetLayerMask;

        #endregion
        
        
        #region ObjectPool function

        private void DestroyObject() => managedArrowPool.Release(this);

        public void SetManagedPool(IObjectPool<Arrow> pool) => managedArrowPool = pool;

        #endregion
    }
}