Question

调用以下函数时游戏停止工作：

错误是：shotmanager对象不会被传递，并且总是为null！我正在按照教程完成他的工作！

我明确地发起了它。

这里有一些编码

namespace SpaceShip
{
    class Enemy: Sprite 
    {
        public shotmanager shotmanager;
        private double timesincelastshot;
        private const int timedelay = 1;
        private Vector2 pos;

        public Enemy(Texture2D Text, Vector2 VEC, Rectangle REC, shotmanager shotmanager)
            : base(Text, VEC, REC)
        {
            shipspeed = 300;
            this.shotmanager = shotmanager;
        }

        public override void Update(KeyboardState keyboard, GameTime gameTime)
        {
            var random = new Random();
            if (Velocity == Vector2.Zero)
            {
                var direction = random.Next(2);
                Velocity = new Vector2(direction == 0 ? -1 : 1, 0);
            }
            else if (gameTime.ElapsedGameTime.Seconds % 2 == 0)
            {
                if (random.Next(15) == 0)
                    Velocity = new Vector2(-velocity.X, velocity.Y);
            }

            timesincelastshot += gameTime.ElapsedGameTime.TotalSeconds;
            if (timesincelastshot > timedelay)
            {
                if (random.Next(2) == 0)
                    pos = calculateposition();
                shotmanager.fireenemyshot(pos);

                timesincelastshot = 0;

            }
            base.Update(keyboard, gameTime);
        }

        private Vector2 calculateposition()
        {
            return VEC + new Vector2(TEXT.Width/2, TEXT.Height/2);
        }
    }
}

namespace SpaceShip
{
    public class shotmanager
    {
        private Shot shot;
        public Texture2D shottexture;
        private Rectangle bounds;
        private List<Shot> shotgroup = new List<Shot>();
        //public shooting shot;
        Vector2 vec;

        public shotmanager(Texture2D shottexture, Rectangle bounds)
        {
            // TODO: Complete member initialization
            this.shottexture = shottexture;
            this.bounds = bounds;
        }

        public void fireenemyshot(Vector2 shotposition)
        {
            var inflatebounds = bounds;
            vec = shotposition;

            inflatebounds.Inflate(10, 10);
            shot.Velocity = new Vector2(0, 1);

            shotgroup.Add(shot);
            shot = new Shot(shottexture, shotposition, inflatebounds);
        }

        public void draw(SpriteBatch spriteBatch)
        {
            foreach (var i in shotgroup)
                shot.draw(spriteBatch);
        }

        public void Update(KeyboardState keyboard, GameTime gameTime)
        {
            foreach (var i in shotgroup)
                shot.Update(keyboard, gameTime);
        }

    }
}

namespace SpaceShip
{
    /// <summary>
    /// This is the main type for your game
    /// </summary>
    public class Game1 : Microsoft.Xna.Framework.Game
    {
        GraphicsDeviceManager graphics;
        SpriteBatch spriteBatch;
        Sprite background;
        shipclass spaceship;
        //Sprite spaceship;
        SpriteFont score;
        EnemyManger enemy;
        Texture2D shottexture;
        public  shotmanager shotmanager;

        public Game1()
        {
            graphics = new GraphicsDeviceManager(this);
            Content.RootDirectory = "Content";
        }

        /// <summary>
        /// Allows the game to perform any initialization it needs to before starting to run.
        /// This is where it can query for any required services and load any non-graphic
        /// related content.  Calling base.Initialize will enumerate through any components
        /// and initialize them as well.
        /// </summary>
        protected override void Initialize()
        {
            // TODO: Add your initialization logic here

            base.Initialize();
        }

        /// <summary>
        /// LoadContent will be called once per game and is the place to load
        /// all of your content.
        /// </summary>
        protected override void LoadContent()
        {
            // Create a new SpriteBatch, which can be used to draw textures.

            var alienship = Content.Load<Texture2D>("flying_saucer_2");

            Texture2D spaceshiptexture;
            spriteBatch = new SpriteBatch(GraphicsDevice);
            spaceshiptexture = Content.Load<Texture2D>("1358114942_kspaceduel");
            var positionx = (graphics.GraphicsDevice.Viewport.Width - spaceshiptexture.Width) / 2;
            var positiony = (graphics.GraphicsDevice.Viewport.Height - spaceshiptexture.Height );
            var ship = new Rectangle(0, graphics.GraphicsDevice.Viewport.Height - spaceshiptexture.Height -150 , graphics.GraphicsDevice.Viewport.Width, spaceshiptexture.Height+150);
            background = new Sprite(Content.Load<Texture2D>("large_space_1920x1200"), Vector2.Zero, graphics.GraphicsDevice.Viewport.Bounds);
            spaceship = new shipclass(spaceshiptexture, new Vector2(positionx, positiony), ship);
            score = Content.Load<SpriteFont>("SpriteFont1");
            shottexture = Content.Load<Texture2D>("64px-SpaceInvadersLaserDepiction");
            shotmanager = new shotmanager(shottexture, graphics.GraphicsDevice.Viewport.Bounds);

            enemy = new EnemyManger(alienship, graphics.GraphicsDevice.Viewport.Bounds, shotmanager);

Answer 1

public void fireenemyshot(Vector2 shotposition)    
{
    var inflatebounds = bounds;
    vec = shotposition;

    inflatebounds.Inflate(10, 10);
    // CULPRIT HERE
    shot.Velocity = new Vector2(0, 1);

    shotgroup.Add(shot);

    // THIS IS DONE TOO LATE.
    shot = new Shot(shottexture, shotposition, inflatebounds);
}

问题在于您尝试在Velocity上设置shot，但在此之前您从未实例化过它。您在尝试使用它之后将其实例化。

编辑 - 仅供参考 ~~您从pos传入此方法的Enemy也从未设置过。它是一个结构，所以它应该被初始化，但是，你永远不会给它一个值。~~ 没关系，我看到了它的设定位置。

无法将对象从类传递到另一个

1 个答案: