Traveller/scripts/projectile/ProjectileTemplate.cs

using System;

using ColdMint.scripts.camp;
using ColdMint.scripts.character;
using ColdMint.scripts.damage;
using ColdMint.scripts.inventory;
using ColdMint.scripts.pickable;
using Godot;

namespace ColdMint.scripts.projectile;

/// <summary>
/// <para>Projectile template</para>
/// <para>抛射体模板</para>
/// </summary>
public partial class ProjectileTemplate : CharacterBody2D
{
    protected long Life;

    //The durability of the projectile
    //抛射体的耐久度
    //When the projectile hits the object, the durability will be reduced, and when the durability is less than or equal to 0, the projectile will be destroyed
    //当抛射体撞击到物体时，会减少耐久度，当耐久度小于等于0时，销毁抛射体
    protected double Durability;

    protected int MaxDamage;
    protected int MinDamage;
    protected int DamageType;

    /// <summary>
    /// <para>After this time destroy the projectile</para>
    /// <para>超过此时刻销毁抛射体</para>
    /// </summary>
    private DateTime? _destructionTime;


    /// <summary>
    /// <para>The impact area of the bullet</para>
    /// <para>子弹的碰撞区域</para>
    /// </summary>
    protected Area2D? Area2D;

    /// <summary>
    /// <para>knockback</para>
    /// <para>击退</para>
    /// </summary>
    /// <remarks>
    ///<para>How much force does it have when hitting the character? Unit: Number of cells，The X direction of the force is inferred automatically.</para>
    ///<para>当击中角色时带有多大的力？单位：格数，力的X方向是自动推断的。</para>
    /// </remarks>
    protected Vector2 KnockbackForce;

    public float Speed => GetMeta("Speed", "15").AsSingle();

    /// <summary>
    /// <para>The master of the weapon</para>
    /// <para>武器的主人</para>
    /// </summary>
    public new Node2D? Owner { get; set; }

    public override void _Ready()
    {
        //The bullet's impact detection area
        //子弹的碰撞检测区域
        Area2D = GetNode<Area2D>("CollisionDetectionArea");
        Area2D.Monitoring = true;
        Area2D.BodyEntered += OnBodyEnter;
        Area2D.BodyExited += OnBodyExited;
        Durability = GetMeta("Durability",    "1").AsDouble();
        MaxDamage = GetMeta("MaxDamage",      "7").AsInt32();
        MinDamage = GetMeta("MinDamage",      "5").AsInt32();
        DamageType = GetMeta("DamageType",    Config.DamageType.Physical).AsInt32();
        KnockbackForce = GetMeta("Knockback", Vector2.Zero).AsVector2();
        //life(ms)
        //子弹的存在时间(毫秒)
        Life = GetMeta("Life", "10000").AsInt64();
        //If the existence time is less than or equal to 0, then it is set to exist for 10 seconds, and projectiles that exist indefinitely are prohibited
        //如果存在时间小于等于0，那么设置为存在10秒，禁止无限期存在的抛射体
        if (Life <= 0)
        {
            Life = 10000;
        }

        _destructionTime = DateTime.Now.AddMilliseconds(Life);
    }


    /// <summary>
    /// <para>Detect whether harm is allowed</para>
    /// <para>检测是否允许造成伤害</para>
    /// </summary>
    /// <param name="owner"></param>
    /// <param name="target"></param>
    /// <returns></returns>
    private bool CanCauseHarm(Node2D? owner, Node2D target)
    {
        //We must know who the owner of the bullet is in order to determine whether it should cause damage or not
        //我们必须知道子弹的主人是谁，才能判断是否应该造成伤害
        if (owner == null)
        {
            return false;
        }

        if (owner is not CharacterTemplate ownerCharacterTemplate)
        {
            return false;
        }

        if (target is TileMap)
        {
            //When we hit the tile, we return true to prevent the bullet from penetrating the tile.
            //撞击到瓦片时，我们返回true，是为了防止子弹穿透瓦片。
            return true;
        }

        //Match any item now
        //现在使它识别任何物品
        if (target is IItem)
        {
            //Bullets are allowed to strike objects.
            //允许子弹撞击物品。
            return true;
        }

        if (target is not CharacterTemplate characterTemplate)
        {
            return false;
        }

        //First get the owner's camp and compare it with the target camp
        //先获取主人的阵营与目标阵营进行比较
        var canCauseHarm = CampManager.CanCauseHarm(CampManager.GetCamp(ownerCharacterTemplate.CampId),
                                                    CampManager.GetCamp(characterTemplate.CampId));
        return canCauseHarm;
    }

    /// <summary>
    /// <para>Executive injury treatment</para>
    /// <para>执行伤害处理</para>
    /// </summary>
    /// <param name="owner"></param>
    /// <param name="target"></param>
    private void DoDamage(Node2D? owner, Node2D target)
    {
        if (target is CharacterTemplate characterTemplate)
        {
            //Allow damage to be caused
            //允许造成伤害
            var damage = new Damage
            {
                Attacker = owner,
                MaxDamage = MaxDamage,
                MinDamage = MinDamage
            };
            damage.CreateDamage();
            damage.MoveLeft = Velocity.X < 0;
            damage.Type = DamageType;
            characterTemplate.Damage(damage);
            if (KnockbackForce != Vector2.Zero)
            {
                //If we set the attack force, then apply the force to the object
                //如果我们设置了攻退力，那么将力应用到对象上
                var force = new Vector2();
                var forceX = Math.Abs(KnockbackForce.X);
                if (Velocity.X < 0)
                {
                    //Beat back to port
                    //向左击退
                    forceX = -forceX;
                }

                force.X = forceX * Config.CellSize;
                force.Y = KnockbackForce.Y * Config.CellSize;
                characterTemplate.AddForce(force);
            }
        }
        else if (target is PickAbleTemplate pickAbleTemplate)
        {
            if (KnockbackForce != Vector2.Zero)
            {
                //If we set the attack force, then apply the force to the object
                //如果我们设置了攻退力，那么将力应用到对象上
                var force = new Vector2();
                var forceX = Math.Abs(KnockbackForce.X);
                if (Velocity.X < 0)
                {
                    //Beat back to port
                    //向左击退
                    forceX = -forceX;
                }

                force.X = forceX * Config.CellSize;
                force.Y = KnockbackForce.Y * Config.CellSize;
                pickAbleTemplate.ApplyImpulse(force);
            }
        }
    }

    /// <summary>
    /// <para>When the bullet is in contact with the node</para>
    /// <para>当子弹与节点接触时</para>
    /// </summary>
    /// <param name="node"></param>
    protected virtual void OnBodyEnter(Node2D node)
    {
        //Here we test whether harm is allowed, notice that for TileMap, we directly allow harm.
        //这里我们检测是否允许造成伤害，注意对于TileMap，我们直接允许造成伤害。
        var canCauseHarm = CanCauseHarm(Owner, node);
        if (!canCauseHarm)
        {
            return;
        }

        DoDamage(Owner, node);
        //Please specify in the Mask who the bullet will collide with
        //请在Mask内配置子弹会和谁碰撞
        //When a bullet hits an object, its durability decreases
        //子弹撞击到物体时，耐久度减少
        Durability--;
        if (Durability <= 0)
        {
            //When the durability is less than or equal to 0, destroy the bullet
            //当耐久度小于等于0时，销毁子弹
            QueueFree();
        }
    }

    /// <summary>
    /// <para>When the bullet leaves the node</para>
    /// <para>当子弹离开节点时</para>
    /// </summary>
    /// <param name="node"></param>
    protected virtual void OnBodyExited(Node2D node) { }


    /// <summary>
    /// <para>When beyond the time of existence</para>
    /// <para>当超过存在时间</para>
    /// </summary>
    private void OnTimeOut()
    {
        QueueFree();
    }

    public override void _Process(double delta)
    {
        //If the existence time is exceeded, the projectile is destroyed
        //如果超过了存在时间，那么销毁抛射体
        if (DateTime.Now >= _destructionTime)
        {
            OnTimeOut();
        }
    }

    public override void _PhysicsProcess(double delta)
    {
        MoveAndSlide();
    }
}