排列具有缩放和围绕任意点旋转的精灵

本文关键字:任意点 旋转 精灵 缩放 排列 | 更新日期: 2023-09-27 17:57:46

我有两个精灵,当它们绘制在一起时,会在屏幕上形成正确的图像。不能同时绘制它们。

想象一下这个类:

class MyImage
{
    Vector2 drawOffset;  // this gets added before the image is drawn
    Vector2 sourceRect;  // this is where it is on the source texturepage
    void Draw(Vector2 position)
    {
        position = position + drawOffset;
        spriteBatch.Draw(sourceTexture, position, sourceRect, Color.White);
    }
}

这个代码调用它:

MyImage a = new MyImage();  // assume they get initialised correctly
MyImage b = new MyImage();  // with different drawOffsets and sourceRects
a.Draw(position);  // this composes the final
b.Draw(position);  // screen image from the 2 source images

现在我想为Draw()函数添加缩放和旋转,但在正确获取SpriteBatch.Draw函数的参数时遇到了真正的问题。这将是采用比例、旋转和原点的版本。我需要最终合成的图像来正确缩放和旋转(围绕某个任意中心),但我一生都无法解决如何操作缩放、旋转和原点参数,使两个图像看起来协调缩放和旋转。以前有人做过这样的事吗?如果有什么不清楚的地方,很乐意根据反馈修改问题。如果图片有帮助,我可以把它们张贴在某个地方。。。

我已经看了关于点xna2D的旋转,但仍然被难住了。

干杯,查理。


非常感谢下面的答案——使用它,我成功地获得了正确的图像渲染。还有一个问题,那就是我似乎需要使用大量的spritebatch。开始/结束对(每个图像渲染一个)。我还没有办法衡量这个设备的性能,帧速率也不高,所以我想这不是问题。

这是我的代码:

// gr is the graphic object:
// gr.position is the location of the image in the atlas
// gr.DrawOffset is the draw offset so the image is placed correctly in it's virtual box
// gr.pageIndex is the index into the texture/atlas array
// hw,hh are half the width/height of the image (it always rotates around it's centre in fact)
Matrix m = Matrix.CreateTranslation(-hw, -hh, 0) *
    Matrix.CreateRotationZ(rotation) *                   // rotation : parameter
    Matrix.CreateScale(scale) *                          // scale : parameter
    Matrix.CreateTranslation(pos.X + hw, pos.Y + hh, 0); // pos : parameter!
spriteBatch.Begin(SpriteSortMode.Deferred, null, null, null, null, null, m);
spriteBatch.Draw(page[gr.pageIndex].texture, gr.DrawOffset, gr.position, color);
spriteBatch.End();

排列具有缩放和围绕任意点旋转的精灵

如果你要使用SpriteBatch。Draw来绘制纹理,我建议你放弃尝试操纵原点、缩放参数来尝试实现这一点,只是我怀疑这种方式是否可行。但您确实有一个替代方案,您可以操纵SpriteBatch矩阵。

这里有一个快速而肮脏的例子,请注意,我在这里使用的纹理是128x96,所以我对该图像大小的值进行了硬编码。不要在这段代码中寻找任何最佳实践,我写这段代码是为了尽可能干净地展示这个概念。

using System;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
namespace WindowsGame1
{
  /// <summary>
  /// This is the main type for your game
  /// </summary>
  public class Game1 : Microsoft.Xna.Framework.Game
  {
    GraphicsDeviceManager graphics;
    SpriteBatch spriteBatch;
    private Texture2D _texture;
    private MyImage _image1;
    private MyImage _image2;
    // Attributes of the composed sprite
    private float _angle = 0.0f;
    private Vector2 _position = new Vector2(100, 100);
    private Vector2 _rotationPoint = new Vector2(96, 48);
    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.
      spriteBatch = new SpriteBatch(GraphicsDevice);
      _texture = Content.Load<Texture2D>("Gravitar");
      // Create the two MyImage instances
      _image1 = new MyImage(_texture, Vector2.Zero, Vector2.Zero);
      _image2 = new MyImage(_texture, new Vector2(64, 0), new Vector2(64, 0));
    }
    /// <summary>
    /// UnloadContent will be called once per game and is the place to unload
    /// all content.
    /// </summary>
    protected override void UnloadContent()
    {
      // TODO: Unload any non ContentManager content here
    }
    /// <summary>
    /// Allows the game to run logic such as updating the world,
    /// checking for collisions, gathering input, and playing audio.
    /// </summary>
    /// <param name="gameTime">Provides a snapshot of timing values.</param>
    protected override void Update(GameTime gameTime)
    {
      // Allows the game to exit
      if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
        this.Exit();
      float elapsedTime = (float)gameTime.ElapsedGameTime.TotalSeconds;
      _angle += 0.5f * elapsedTime;
      if (Mouse.GetState().LeftButton == ButtonState.Pressed)
      {
        _angle = 0.0f;
      }
      if (Keyboard.GetState().IsKeyDown(Keys.Left)) 
        _position += new Vector2(-10, 0)*elapsedTime;
      if (Keyboard.GetState().IsKeyDown(Keys.Right)) 
        _position += new Vector2(10, 0) * elapsedTime;
      base.Update(gameTime);
    }
    /// <summary>
    /// This is called when the game should draw itself.
    /// </summary>
    /// <param name="gameTime">Provides a snapshot of timing values.</param>
    protected override void Draw(GameTime gameTime)
    {
      GraphicsDevice.Clear(Color.CornflowerBlue);
      // Setup the sprite batch matrix      
      // Notice that we first translate to the point or rotation
      // then rotate and when we translate to the desired position we
      // need to compensate for the first translation so that the texture
      // appears at the correct location
      Matrix m = 
        Matrix.CreateScale(1.5f) 
        * Matrix.CreateTranslation(-_rotationPoint.X, -_rotationPoint.Y, 0) 
        * Matrix.CreateRotationZ(_angle) 
        * Matrix.CreateTranslation(_position.X + _rotationPoint.X, _position.Y + _rotationPoint.Y, 0);
      // Begin the SpriteBatch passing the matrix
      spriteBatch.Begin(SpriteSortMode.Deferred, null, null, null, null, null, m);
      _image1.Draw(spriteBatch);
      _image2.Draw(spriteBatch);            
      spriteBatch.End();
      base.Draw(gameTime);
    }
    class MyImage
    {
      Vector2 _drawOffset;
      Vector2 _sourcePoint;
      Texture2D _sourceTexture;      
      public MyImage(Texture2D sourceTexture, Vector2 sourcePoint, Vector2 drawOffset)
      {
        _drawOffset = drawOffset;
        _sourcePoint = sourcePoint;
        _sourceTexture = sourceTexture;
      }
      public void Draw(SpriteBatch spriteBatch)
      {      
        spriteBatch.Draw(_sourceTexture, _drawOffset, 
          new Rectangle((int)_sourcePoint.X, (int)_sourcePoint.Y, 64, 96), 
          Color.White);
      }
    }
  }
}