ichni_Creator_Studio/Assets/Scripts/Animations/Transform/LookAt.cs

using System;
using System.Collections;
using System.Collections.Generic;
using Lean.Pool;
using UnityEngine;
using UnityEngine.Serialization;

namespace Ichni.RhythmGame
{
    /// <summary>
    /// 将物体的z轴指向目标物体，注意，LookAt的启用期间，物体的旋转将被锁定
    /// </summary>
    public class LookAt : AnimationBase
    {
        public TransformSubmodule targetTransformSubmodule;
        public BaseElement lookAtObject;
        public FlexibleBool enabling;

        public static LookAt GenerateElement(string elementName, Guid id,
            List<string> tags, BaseElement targetObject,
            BaseElement lookAtTarget, FlexibleBool enabling)
        {
            LookAt look = Instantiate(EditorManager.instance.basePrefabs.emptyObject).AddComponent<LookAt>();

            look.Initialize(elementName, id, tags);
            
            look.targetObject = targetObject;
            look.lookAtObject = lookAtTarget;
            look.enabling = enabling;
            look.animationReturnType = FlexibleReturnType.Before;

            if (targetObject.transformSubmodule != null)
            {
                look.targetTransformSubmodule = targetObject.transformSubmodule;
            }
            else
            {
                throw new System.Exception("Target object does not have a TransformSubmodule");
            }
            
            look.SetParent(targetObject);

            look.timeDurationSubmodule.SetDuration(-999f, 999f); //TODO: 换为(-delay, songLength)

            return look;
        }

        private void Start()
        {
            targetTransformSubmodule = targetObject.transformSubmodule;
        }

        protected override void UpdateAnimation(float songTime)
        {
            enabling.UpdateFlexibleBool(songTime);
            if (enabling.value)
            {
                animationReturnType = FlexibleReturnType.MiddleExecuting;
                Vector3 lookingDirection =
                    (lookAtObject.transform.position - targetObject.transform.position).normalized;

                Vector3 eulerAnglesOffset = Quaternion.LookRotation(lookingDirection).eulerAngles;

                targetTransformSubmodule.eulerAnglesOffsetLock = true;

                targetTransformSubmodule.currentEulerAngles = eulerAnglesOffset;
            }
            else
            {
                animationReturnType = FlexibleReturnType.MiddleInterval;
                targetTransformSubmodule.eulerAnglesOffsetLock = false;
            }
        }
    }
}