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c# - 移动键不按怎么让小船漂流几秒

问题描述

所以我正在尝试制作一个 2D 游戏，其中玩家从头顶控制一艘船。我有它，所以当按下“A”和“D”键时船会旋转，当按下“W”和“S”键时会向前/向后移动。我想让船在释放前进和后退键后以降低的速度漂移几秒钟，但我不知道该怎么做。这是我的 Ship 类代码。我正在考虑以某种方式使用“While”循环，但我不太确定如何。我还希望船头不断更新以朝着创建的旋转方向移动。

我在 main 方法中有一个枚举，这是“Dir”的来源。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;


//width = 62 pixels
//height = 179 pixels

namespace my_first_game
{
class Ship
{

    private Vector2 position = new Vector2(300, 300);
    private int radius = 50;
    private bool ismoving = false;
    private Dir direction = Dir.down;
    private int health = 3;
    private float speed = 200;
    public float angle = 0;
    public double turntime = .01d;
    private float drifting = 0;
    private bool isdrifting = false;

    Vector2 Boat_Tip = new Vector2(0, 0);



   // Constructor for the ship class
   public Ship(int shiphealth)
    {
        shiphealth = health;
    }

    /* public float Get_angle
     {
         get { return angle; }

     }
     */

    //get and set health
    public int Health
    {
        get { return health; }
        set { value = health; }
    }

    // get the ship's position
    public Vector2 Position
    {
        get{ return position; }
    }

    //update loop for the ship's state
    public void update_ship(GameTime gameTime)
    {
        KeyboardState kstate = Keyboard.GetState();
        float dt = (float)gameTime.ElapsedGameTime.TotalSeconds;
        Boat_Tip.X = position.X;
        Boat_Tip.Y = position.Y;

        //if keys are pressed, the ship moves until the keys are unpressed

        if (kstate.IsKeyDown(Keys.W))
        {
            direction = Dir.up;
            ismoving = true;
            isdrifting = true;
        }
        if (kstate.IsKeyDown(Keys.A))
        {
            direction = Dir.left;
            ismoving = true;
        }
        if (kstate.IsKeyDown(Keys.D))
        {
            direction = Dir.right;
            ismoving = true;
        }
        if (kstate.IsKeyDown(Keys.S))
        {
            direction = Dir.down;
            ismoving = true;
        }


        //"ismoving" is used as a flag to move the ship if keys are held
        //angle also rotates the boat when "A" and "D" are pressed
        if (ismoving) {

            switch (direction) {
                case Dir.up:
                    position.Y -= speed * dt;
                    ismoving = false;
                    break;
                case Dir.down:

                    position.Y += speed * dt;
                    ismoving = false;
                    break;
                case Dir.left:
                    position.X -= speed *(float)turntime * dt;
                    angle -= (float).01;
                    ismoving = false;
                    break;
                case Dir.right:
                    position.X += speed *(float)turntime * dt;
                    angle += (float).01;
                    ismoving = false;
                    break;
                default: break;
            }
        }
    }
}

}

不确定这是否有帮助，但这是我的船舶绘制方法：

spriteBatch.Draw(ship_sprite, ship.Position, ship_rectangle, Color.White, 
ship.angle, origin, 1.0f, SpriteEffects.None, 1);

标签： c#monogame

解决方案

一个简单的解决方案是拥有 current_speed 和 target_speed。您的按键只需设置 target_speed，然后在更新时将 current_speed 调整为 target_speed

float cur_speed;
float trg_speed;

void Update()
{
    if( keypressed) trg_speed = 200f;
    else trg_speed = 0f;

    cur_speed = lerp(cur_speed,trg_speed,0.2f);

    // do your other movement here depending on cur_speed
}

类似的东西 - 如果行进距离对于独立于帧率很重要，你必须考虑经过的时间 - 也许使用物理引擎为你做

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