RizzeProjectile/Assets/Scripts/GameplayObjects/Explosion.cs

using Fusion;
using UnityEngine;

namespace Projectiles
{
	/// <summary>
	/// Deals damage to all IHitTargets within specified radius right after spawning.
	/// </summary>
	public class Explosion : ContextBehaviour
	{
		// PRIVATE MEMBERS

		[SerializeField]
		private LayerMask _targetMask;
		[SerializeField]
		private LayerMask _blockingMask;
		[SerializeField]
		private EHitType _hitType = EHitType.Explosion;

		[SerializeField, Tooltip("It is usually better to check from point slightly above explosion to filter out terrain discrepancies")]
		private Vector3 _explosionCheckOffset = new(0f, 0.5f, 0f);
		[SerializeField]
		private float _innerRadius = 1f;
		[SerializeField]
		private float _outerRadius = 6f;

		[SerializeField]
		private float _innerDamage = 100f;
		[SerializeField]
		private float _outerDamage = 10f;
		[SerializeField]
		private bool _canDamageOwner = true;

		[SerializeField]
		private float _despawnDelay = 3f;

		[SerializeField]
		private Transform _effectRoot;

		private TickTimer _despawnTimer;

		// NetworkBehaviour INTERFACE

		public override void Spawned()
		{
			ShowEffect();

			if (HasStateAuthority == true)
			{
				Explode();
			}

			_despawnTimer = TickTimer.CreateFromSeconds(Runner, _despawnDelay);
		}

		public override void FixedUpdateNetwork()
		{
			if (HasStateAuthority == false)
				return;
			if (_despawnTimer.Expired(Runner) == false)
				return;

			Runner.Despawn(Object);
		}

		// PRIVATE METHODS

		private void Explode()
		{
			var hits = ListPool.Get<LagCompensatedHit>(16);
			var hitRoots = ListPool.Get<int>(16);

			var position = transform.position + _explosionCheckOffset;

			var hitOptions = HitOptions.IncludePhysX;
			if (_canDamageOwner == false)
			{
				hitOptions |= HitOptions.IgnoreInputAuthority;
			}

			int count = Runner.LagCompensation.OverlapSphere(position, _outerRadius, Object.InputAuthority, hits, _targetMask, hitOptions);

			bool damageFalloff = _innerRadius < _outerRadius && _innerDamage != _outerDamage;

			for (int i = 0; i < count; i++)
			{
				var hit = hits[i];

				var hitTarget = HitUtility.GetHitTarget(hit.Hitbox, hit.Collider);

				if (hitTarget == null)
					continue;

				int hitRootID = hit.Hitbox != null ? hit.Hitbox.Root.GetInstanceID() : 0;
				if (hitRoots.Contains(hitRootID) == true)
					continue; // Same object was hit multiple times

				var direction = hit.GameObject.transform.position - position;
				float distance = direction.magnitude;
				direction /= distance; // Normalize

				// Check if direction to the hitbox is not obstructed
				if (Runner.GetPhysicsScene().Raycast(position, direction, distance, _blockingMask) == true)
					continue;

				if (hitRootID != 0)
				{
					hitRoots.Add(hitRootID);
				}

				float damage = _innerDamage;

				if (damageFalloff == true && distance > _innerRadius)
				{
					damage = MathUtility.Map(_innerRadius, _outerRadius, _innerDamage, _outerDamage, distance);
				}

				hit.Point = hit.GameObject.transform.position;
				hit.Normal = -direction;

				HitUtility.ProcessHit(Object.InputAuthority, direction, hit, damage, _hitType);
			}

			ListPool.Return(hitRoots);
			ListPool.Return(hits);
		}

		private void ShowEffect()
		{
			if (Runner.Mode == SimulationModes.Server)
				return;

			if (_effectRoot != null)
			{
				_effectRoot.SetActive(true);
				_effectRoot.localScale = Vector3.one * _outerRadius * 2f;
			}
		}
	}
}