rg1/client/Battle/System/Gun/GunAimEnemySystem.cs

using CoreGame;
using Entitas;
using UnityEngine;

namespace CoreGame.Render
{
    public class GunAimEnemySystem : IExecuteSystem
    {
        private readonly IGroup<CombatEntity> m_Group;

        public GunAimEnemySystem(Contexts contexts)
        {
            m_Group = contexts.combat.GetGroup(CombatMatcher.AimTarget);
        }

        public void Execute(float deltaTime)
        {
            m_Group.GetEntities(Contexts.s_CacheEntities);
            if (Contexts.s_CacheEntities.Count == 0)
                return;

            var entities = Contexts.s_CacheEntities;
            for (int i = 0; i < entities.Count; i++)
            {
                var entity = entities[i];
                var aimTarget = entity.aimTarget;

                if (aimTarget.rotationEid == aimTarget.targetEid)
                    continue;
                
                var rotationEnt = Contexts.Combat.GetEntity(aimTarget.rotationEid);
                if (rotationEnt == null)
                    continue;
                
                var targetEntity = Contexts.Combat.GetEntity(aimTarget.targetEid);
                if (targetEntity != null)
                    aimTarget.targetPos = MathViewUtils.ToVector2(TargetSelectSrv.GetCastTargetPos(targetEntity));

                var bindPointProxy = rotationEnt.bindPointProxy;
                if (bindPointProxy == null)
                    continue;

                if (bindPointProxy.TryGetBindPointOrDefault(aimTarget.rotationCtrl, out var bindPoint) == false)
                    continue;

                aimTarget.resetTime -= deltaTime;
                if (aimTarget.resetTime < 0)
                {
                    bindPoint.localEulerAngles = Vector3.zero;
                    entity.RemoveAimTarget();
                    continue;
                }

                var lookDir = aimTarget.targetPos - new Vector2(bindPoint.position.x, bindPoint.position.y);
                lookDir.Normalize();

                var gunDir = aimTarget.gunAimForwardDir;
                var sign = Mathf.Sign(lookDir.x);
                if (aimTarget.rotationEntChangeDir)
                {
                    rotationEnt.transformProxy.SetDirection(lookDir.x < 0 ? Vector2.left : Vector2.right);
                    gunDir.x *= Mathf.Sign(lookDir.x);
                    sign *= Mathf.Sign(gunDir.x * lookDir.y - gunDir.y * lookDir.x);
                }
                var dot = Vector2.Dot(lookDir, gunDir);
                var angle = Mathf.Acos(dot) * Mathf.Rad2Deg * sign;
                // 主人的朝向也要变, 所以说这个系统要在LocationSyncSystem之后执行
                var quaternion = Quaternion.Euler(0, 0, angle);
                var lastQuat = bindPoint.localRotation;
                bindPoint.localRotation = Quaternion.Slerp(lastQuat, quaternion, deltaTime * 20);
            }
        }
    }
}