BITFALL/Assets/Artists/Scripts/UX/UXDamageIndicator.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Threading.Tasks;
using BITKit;
using BITKit.Entities;
using BITKit.Entities.Player;
using BITKit.UX;
using UnityEngine;
using UnityEngine.UIElements;

namespace BITFALL.UX
{
	public class UXDamageIndicator : MonoBehaviour
	{
		[SerializeReference, SubclassSelector] private IPlayerService playerService;
		
	
		[SerializeField] private UIDocument document;

		[SerializeField] private VisualTreeAsset indicatorAsset;
		[UXBindPath("indicator-container")]
		private VisualElement indicatorContainer;
		
		[Inject] private IHealth _health;
		[Inject] private IEntityMovement _movement;

		private List<(VisualElement visualElement, Vector3 position, float exitTime)> _indicators = new();
		
		private void Start()
		{
			playerService.OnPlayerInitialized += OnPlayerInitialized;
			playerService.OnPlayerDisposed+=OnPlayerDisposed;
			destroyCancellationToken.Register(() =>
			{
				playerService.OnPlayerInitialized -= OnPlayerInitialized;
				playerService.OnPlayerDisposed-=OnPlayerDisposed;
			});
			BITKit.UX.UXUtils.Inject(this);
			
			indicatorContainer.Clear();
		}

		private void OnPlayerDisposed(Entity obj)
		{
			foreach (var x in _indicators)
			{
				x.visualElement.RemoveFromHierarchy();
			}
			_indicators.Clear();
		}

		private void OnPlayerInitialized(Entity obj)
		{
			obj.Inject(this);
			
			_health.OnDamageRelease += OnDamageRelease;
		}

		private void Update()
		{
			foreach (var x in _indicators)
			{
				//
				// var direction =Vector3.ProjectOnPlane(x.position - _movement.Position,Vector3.up).normalized;
				//
				// direction = Quaternion.LookRotation(direction) * _movement.Rotation * Vector3.forward;
				//
				// var rotation = Quaternion.LookRotation(direction);
				// var angle =(rotation.eulerAngles.y+180)%360;
				//
				// x.visualElement.transform.rotation = Quaternion.Euler(0, 0, -angle);
				
				//Calculate direction 
				Vector3 rhs = x.position - _movement.Position;
				Vector3 offset = x.visualElement.transform.rotation.eulerAngles;

				var forward = _movement.Forward;
				//Convert angle into screen space
				rhs.y = 0f;
				rhs.Normalize();
				//Get the angle between two positions.
				float angle = Vector3.Angle(rhs, forward);
				//Calculate the perpendicular of both vectors
				//More information about this calculation: https://unity3d.com/es/learn/tutorials/modules/beginner/scripting/vector-maths-dot-cross-products?playlist=17117
				Vector3 Perpendicular = Vector3.Cross(forward, rhs);
				//Calculate magnitude between two vectors
				float dot = -Vector3.Dot(Perpendicular, Vector3.up);
				//get the horizontal angle in direction of target / sender.
				angle = AngleCircumference(dot, angle);
				//Apply the horizontal rotation to the indicator.
				offset.z = -angle;
			
				x.visualElement.transform.rotation = Quaternion.Euler(offset);

				if (Time.time > x.exitTime)
					x.visualElement.RemoveFromHierarchy();
				
                float AngleCircumference(float dot, float angle)
				{
					float ac = angle;
					float circumference = 360f;
					ac = angle - 10;
					if (dot < 0)
					{
						ac = circumference - angle;
					}
					return ac;
				}
			}
			_indicators.RemoveAll(x => x.exitTime < Time.time);
		}

		private void OnDamageRelease(DamageMessage arg1)
		{
			if (arg1.Position.IsDefault()) return;
			
			var indicator =indicatorContainer.Create<VisualElement>(()=>indicatorAsset.CloneTree()[0]);

			if (arg1.Damage is 0)
			{
				indicator[0].style.unityBackgroundImageTintColor = Color.black;
			}
			
			_indicators.Add((indicator, (Vector3)arg1.Position, Time.time + 1));
		}

		// private async void KillIndicator(VisualElement indicator)
		// {
		// 	try
		// 	{
		// 		await Task.Delay(500, destroyCancellationToken);
		// 		indicator.RemoveFromHierarchy();
		// 	}
		// 	catch (Exception e)
		// 	{
		// 		Console.WriteLine(e);
		// 		throw;
		// 	}
		// }
	}

}