project-reset/Assets/Scripts/Core/LockOnManager.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Numerics;
using Sirenix.OdinInspector;
using Unity.Cinemachine;
using UnityEngine;
using UnityEngine.UIElements;
using Vector2 = UnityEngine.Vector2;
using Vector3 = UnityEngine.Vector3;

public class LockOnManager : MonoBehaviour{
    [ShowInInspector]
    public UIDocument lockOnDocument;
    public GameObject lockOnTarget;
    public CinemachineTargetGroup targetGroup;

    public float lockOnRange;

    [Space(5)]
    public List<GameObject> lockOnTargets = new List<GameObject>(); 

    private Label elementLabelName;
    private VisualElement elementRoot; 
    // Start is called once before the first execution of Update after the MonoBehaviour is created
    void Start()
    {
        if (lockOnTarget.GetComponent<ILockOnTarget>() == null) {
            Debug.LogError($"Game Object {lockOnTarget.name} does not implement the ILockOnTarget interface. Not processing lock-on actions!");
        }
        
        elementRoot = lockOnDocument.rootVisualElement.Query<VisualElement>("LockOnGroup");
        elementLabelName = lockOnDocument.rootVisualElement.Query<Label>("LockOnName").First();

        
        // Add all nearby game objects to lock-on eligible list
        GameObject[] allGameObjects = GameObject.FindObjectsByType<GameObject>(0, 0);
        
        foreach (GameObject thisObject in allGameObjects)
        {
            if (Vector3.Distance(transform.position, thisObject.transform.position) < lockOnRange) {
                if (thisObject.GetComponent<ILockOnTarget>() != null){
                    lockOnTargets.Add(thisObject);
                }
            }
        }
    }

    void Update(){
        targetGroup.Targets[1].Weight = Mathf.Lerp(targetGroup.Targets[1].Weight, .2f, 5f * Time.deltaTime);

        for (int i = 2; i < targetGroup.Targets.Count; i++) {
            if (targetGroup.Targets[i].Weight < 0.001f) {
                StartCoroutine(RemoveFromTargetAtFrameEnd(i));
                continue;
            }

            targetGroup.Targets[i].Weight = Mathf.Lerp(targetGroup.Targets[i].Weight, 0f, 8f * Time.deltaTime);
        }
    }

    IEnumerator RemoveFromTargetAtFrameEnd(int index){
        yield return new WaitForEndOfFrame();
        targetGroup.Targets.RemoveAt(index);
    }

    public void ChangeLockOnTarget(){
        if (!lockOnTarget) {
            // If there is no target, simply find the closest to the center of the camera
            GameObject mostForwardGameObject = null;
            float mostForwardAngle = Mathf.Infinity;

            foreach (GameObject target in lockOnTargets) {
                // Skip targets behind walls
                if (!Physics.Raycast(Camera.main.transform.position, target.transform.position)) {
                    continue;
                }
                
                Vector3 dirToTarget = transform.position - target.transform.position;
                float angleToTarget = Vector3.Angle(Camera.main.transform.forward, dirToTarget);
                
                // Set the new target to closest to screen
                if (angleToTarget < mostForwardAngle) {
                    mostForwardAngle = angleToTarget;
                    mostForwardGameObject = target;
                }
            }
            
            // Set the winner to the new target 
            lockOnTarget = mostForwardGameObject;
        } else {
            // Set it to either the next in the list or the first, if there already is a target
            int desiredIndex;
            
            if (lockOnTargets.IndexOf(lockOnTarget) == lockOnTargets.Count - 1) {
                desiredIndex = 0;
            } else {
                desiredIndex = lockOnTargets.IndexOf(lockOnTarget) + 1;
            }
            
            lockOnTarget = lockOnTargets[desiredIndex];
            targetGroup.Targets.Insert(1, new CinemachineTargetGroup.Target{
                Object = lockOnTargets[desiredIndex].transform,
                Radius = 1f,
                Weight = 0f
            });
        }
    }

    void LateUpdate(){
        if (lockOnTarget.GetComponent<ILockOnTarget>() != null) {
            // This is just test logic to get an image above a lock on.
            // TODO: Replace with something less silly
            Vector2 screenPos = RuntimePanelUtils.CameraTransformWorldToPanel(
                lockOnDocument.rootVisualElement.panel, 
                lockOnTarget.GetComponent<ILockOnTarget>().GetReticlePosition(),
                Camera.main.GetComponent<Camera>()
            );
            
            // Set name
            elementLabelName.text = lockOnTarget.name;
            
            // Set position (add the width/height of the element)
            elementRoot.style.top = new StyleLength(screenPos.y - elementRoot.resolvedStyle.height * .7f );
            elementRoot.style.left = new StyleLength(screenPos.x - elementRoot.resolvedStyle.width / 2f);
            
            // Set enabled
            elementRoot.SetEnabled(true);
        } else {
            elementRoot.SetEnabled(false);
        }
    }
}