XNA：向上、向下、向左和向右滚动线性环绕、旋转纹理：

Question

我正在为 PC 开发一个基于 XNA 的简单游戏，我的游戏屏幕窗口大小为 1024 X 768，我想在我移动鼠标的方向上滚动一个线性包裹的旋转纹理，大小为 1280 X 1280。

这个纹理的原点已设置为它的中心点 (640, 640)，然后我将这个纹理放在屏幕上我的游戏窗口中间 (512, 384)。

到目前为止，我的代码（完整粘贴在下面）可以完美运行，直到我将旋转引入到混合中。

public class Game1 : Microsoft.Xna.Framework.Game
{

    GraphicsDeviceManager graphics;

    SpriteBatch spriteBatch;

    int x;
    int y;

    float z = 250f;

    Texture2D Overlay;

    Texture2D RotatingBackground;

    Rectangle? sourceRectangle;

    Color color;

    float rotation;

    Vector2 ScreenCenter;

    Vector2 Origin;

    Vector2 scale;

    Vector2 Direction;

    SpriteEffects effects;

    float layerDepth;

    public Game1()
    {

        graphics = new GraphicsDeviceManager(this);

        Content.RootDirectory = "Content";

    }

    protected override void Initialize()
    {

        graphics.PreferredBackBufferWidth = 1024;

        graphics.PreferredBackBufferHeight = 768;

        graphics.ApplyChanges();

        Direction = Vector2.Zero;    

        IsMouseVisible = true;

        ScreenCenter = new Vector2(graphics.PreferredBackBufferWidth / 2, graphics.PreferredBackBufferHeight / 2);

        Mouse.SetPosition((int)graphics.PreferredBackBufferWidth / 2, (int)graphics.PreferredBackBufferHeight / 2);

        sourceRectangle = null;

        color = Color.White;

        rotation = 0.0f;

        scale = new Vector2(1.0f, 1.0f);

        effects = SpriteEffects.None;

        layerDepth = 1.0f;

        base.Initialize();

    }

    protected override void LoadContent()
    {

        spriteBatch = new SpriteBatch(GraphicsDevice);

        Overlay = Content.Load<Texture2D>("Overlay");

        RotatingBackground = Content.Load<Texture2D>("Background");

        Origin = new Vector2((int)RotatingBackground.Width / 2, (int)RotatingBackground.Height / 2);

    }


    protected override void UnloadContent()
    {

    }

    protected override void Update(GameTime gameTime)
    {

        float timePassed = (float)gameTime.ElapsedGameTime.TotalSeconds;

        MouseState ms = Mouse.GetState();

        Vector2 MousePosition = new Vector2(ms.X, ms.Y);

        Direction = ScreenCenter - MousePosition;

        if (Direction != Vector2.Zero)
        {

            Direction.Normalize();

        }

        x += (int)(Direction.X * z * timePassed);

        y += (int)(Direction.Y * z * timePassed);


        //No rotation = texture scrolls as intended, With rotation = texture no longer scrolls in the direction of the mouse. My update method needs to somehow compensate for this.         
        //rotation += 0.01f;  

        base.Update(gameTime);

    }

    protected override void Draw(GameTime gameTime)
    {

        spriteBatch.Begin(SpriteSortMode.Deferred, null, SamplerState.LinearWrap, null, null);

        spriteBatch.Draw(RotatingBackground, ScreenCenter, new Rectangle(x, y, RotatingBackground.Width, RotatingBackground.Height), color, rotation, Origin, scale, effects, layerDepth);

        spriteBatch.Draw(Overlay, Vector2.Zero, Color.White);

        spriteBatch.End();

        base.Draw(gameTime);

    }
}  

例如，如果我要将纹理向右旋转，然后将鼠标从屏幕中心直接向上移动会导致纹理向右斜向上滚动 - 这不是我的意图 - 如果我将鼠标移动到任何位置方向 我希望我的纹理在那个方向上滚动，就像我从未在混合中引入旋转一样。

如何改变我的 Update() 方法来实现这一点？

感谢阅读.....

Answer 1

根据您的问题，我推测您希望鼠标控制相机，而旋转仅影响纹理。 为此，所需的更改会影响 Draw 方法。调用 Spritebatch.Begin 时，您应该使用 x 和 y 值将转换矩阵作为参数传递。这允许您在世界坐标中旋转纹理，同时独立于旋转移动相机。

检查这个问题 - Spritebatch.Begin() Transform Matrix - 了解变换矩阵的工作原理。

Answer 2

这似乎有效。可能有一个更优雅的解决方案，但它肯定是一个需要解决的巧妙问题。

public class Game1 : Microsoft.Xna.Framework.Game
{

    GraphicsDeviceManager graphics;

    SpriteBatch spriteBatch;

    int x;
    int y;

    float z = 250f;

    Texture2D Overlay;

    Texture2D RotatingBackground;

    Rectangle? sourceRectangle;

    Color color;

    float rotation;

    Vector2 ScreenCenter;

    Vector2 Origin;

    Vector2 scale;

    Vector2 Direction;

    SpriteEffects effects;

    float layerDepth;

    public Game1()
    {

        graphics = new GraphicsDeviceManager(this);

        Content.RootDirectory = "Content";

    }

    protected override void Initialize()
    {

        graphics.PreferredBackBufferWidth = 1024;

        graphics.PreferredBackBufferHeight = 768;

        graphics.ApplyChanges();

        Direction = Vector2.Zero;

        IsMouseVisible = true;

        ScreenCenter = new Vector2(graphics.PreferredBackBufferWidth / 2, graphics.PreferredBackBufferHeight / 2);

        Mouse.SetPosition((int)graphics.PreferredBackBufferWidth / 2, (int)graphics.PreferredBackBufferHeight / 2);

        sourceRectangle = null;

        color = Color.White;

        rotation = 0.0f;

        scale = new Vector2(1.0f, 1.0f);

        effects = SpriteEffects.None;

        layerDepth = 1.0f;

        base.Initialize();

    }

    protected override void LoadContent()
    {

        spriteBatch = new SpriteBatch(GraphicsDevice);

        Overlay = Content.Load<Texture2D>("Overlay");

        RotatingBackground = Content.Load<Texture2D>("Background");

        Origin = new Vector2((int)RotatingBackground.Width / 2, (int)RotatingBackground.Height / 2);

    }


    protected override void UnloadContent()
    {

    }

    protected override void Update(GameTime gameTime)
    {
        float timePassed = (float)gameTime.ElapsedGameTime.TotalSeconds;

        MouseState ms = Mouse.GetState();

        Vector2 MousePosition = new Vector2(ms.X, ms.Y);

        Direction = ScreenCenter - MousePosition;

        if (Direction != Vector2.Zero)
        {

            float angle = 0;
            angle = (float)Math.Atan2(Direction.Y, Direction.X) - rotation;
            Direction.X = (float)Math.Cos(angle);
            Direction.Y = (float)Math.Sin(angle);
            Direction.Normalize();
        }

        x += (int)(Direction.X * z * timePassed);
        y += (int)(Direction.Y * z * timePassed);


        //No rotation = texture scrolls as intended, With rotation = texture no longer scrolls in the direction of the mouse. My update method needs to somehow compensate for this.         
        rotation += .01f ;
        if (rotation > MathHelper.Pi * 2)
        {
            rotation -= (MathHelper.Pi * 2);
        }
        base.Update(gameTime);

    }

    protected override void Draw(GameTime gameTime)
    {

        spriteBatch.Begin(SpriteSortMode.Deferred, null, SamplerState.LinearWrap, null, null);

        spriteBatch.Draw(RotatingBackground, ScreenCenter, new Rectangle(x, y, RotatingBackground.Width, RotatingBackground.Height), color, rotation, Origin, scale, effects, layerDepth);
        spriteBatch.Draw(Overlay, Vector2.Zero, Color.White);

        spriteBatch.End();

        base.Draw(gameTime);

    }
}