C# 写入RenderTarget后，如何高效地克隆输出？

XNA noob在这里，每天学习。我刚刚研究了如何使用RenderTarget2D将多个纹理合成为一个纹理。但是，尽管我可以在大多数情况下将RenderTarget2D用作纹理2D，但有一个关键区别：当调整backbuffer的大小时（毫无疑问，在其他情况下，如内存不足的图形设备），这些渲染纹理将丢失

目前，我只是将完成的RenderTarget2D复制到一个新的非易失性Texture2D对象中。不过，我的代码非常复杂。有没有比这更优雅的方法？也许我只是累了，但我在谷歌上找不到答案

稍微简化：

public static Texture2D  MergeTextures(int width, int height, IEnumerable<Tuple<Texture2D, Color>> textures)
    {
    RenderTarget2D  buffer = new RenderTarget2D(_device, width, height);

    _device.SetRenderTarget(buffer);
    _device.Clear(Color.Transparent);

    SpriteBatch  spriteBatch = new SpriteBatch(_device);
    spriteBatch.Begin(SpriteSortMode.Immediate, BlendState.NonPremultiplied);

    // Paint each texture over the one before, in the appropriate color
    Rectangle  rectangle = new Rectangle(0, 0, width, height);
    foreach (Tuple<Texture2D, Color> texture in textures)
        spriteBatch.Draw(texture.Item1, rectangle, texture.Item2);

    spriteBatch.End();
    _device.SetRenderTarget((RenderTarget2D)null);

    // Write the merged texture to a Texture2D, so we don't lose it when resizing the back buffer
    // This is POWERFUL ugly code, and probably terribly, terribly slow
    Texture2D  mergedTexture = new Texture2D(_device, width, height);
    Color[]    content       = new Color[width * height];
    buffer.GetData<Color>(content);
    mergedTexture.SetData<Color>(content);
    return mergedTexture;
    }

公共静态纹理2D合并纹理（int-width、int-height、IEnumerable纹理）
{
RenderTarget2D缓冲区=新的RenderTarget2D（_设备、宽度、高度）；
_device.SetRenderTarget（缓冲区）；
_设备。清晰（彩色。透明）；
SpriteBatch SpriteBatch=新SpriteBatch（_设备）；
spriteBatch.Begin（SpriteSortMode.Immediate、BlendState.NonPremultiplied）；
//在前一个纹理上以适当的颜色绘制每个纹理
矩形=新矩形（0，0，宽度，高度）；
foreach（纹理中的元组纹理）
绘制（texture.Item1，矩形，texture.Item2）；
spriteBatch.End（）；
_device.SetRenderTarget（（RenderTarget2D）null）；
//将合并的纹理写入Texture2D，以便在调整后缓冲区大小时不会丢失它
//这是一个强大而丑陋的代码，而且可能非常非常缓慢
Texture2D mergedTexture=新的Texture2D（_设备、宽度、高度）；
颜色[]内容=新颜色[宽度*高度]；
获取数据（内容）；
mergedTexture.SetData（内容）；
返回合并文本；
}

我想我应该检查IsContentLost并根据需要重新渲染，但是这发生在我的主要绘图循环中间，当然你不能嵌套分批。我可以维护一个“渲染待办事项”列表，在主SpriteBatch结束后处理它们，然后它们就可以用于下一帧。这是首选策略吗

---

这段代码只调用了几次，所以性能不是一个问题，但我想学习如何正确处理。

事实上，如果您在正常加载内容（游戏开始、级别更改、房间更改等）时，在一次性过程中生成纹理，那么您的代码并没有那么糟糕。你们在CPU和GPU之间传输纹理，和加载普通的ol纹理一样。它很简单而且很有效

如果您更频繁地生成纹理，并且它开始成为每帧成本，而不是加载时间成本，那么您将需要担心它的性能，并可能将它们保留为渲染目标

你不应该在绘图中间获得<代码>内容丢失<代码>，这样你就可以安全地响应这个事件，然后重新创建渲染目标。或者，您可以在每一帧上检查

IsContentLost

，最好是在渲染其他内容之前在帧的开头。无论哪种方式，都应该在

SpriteBatch

开始之前检查所有内容

---

（通常在使用渲染目标时，您会在每一帧中重新生成它们，因此在这种情况下不需要检查它们。）

如果在其他地方绘制渲染目标时遇到动态调整渲染目标大小的问题，您可以使用设置大小的屏幕外rendertarget，将完成的RT复制为如下所示：

Rendertarget2D offscreenRT = new RenderTarget2D(_device, width, height);
_device.SetRenderTarget(offscreenRT);
_device.Clear(Color.Transparent);

SpriteBatch  spriteBatch = new SpriteBatch(_device);
spriteBatch.Begin(SpriteSortMode.Immediate, BlendState.NonPremultiplied);
spriteBatch.Draw(buffer, Vector2.Zero, Color.White);
spriteBatch.End();
_device.SetRenderTarget(null);

替换

Texture2D  mergedTexture = new Texture2D(_device, width, height);
Color[]    content       = new Color[width * height];
buffer.GetData<Color>(content);
mergedTexture.SetData<Color>(content);
return mergedTexture;

因为RenderTarget2D扩展了Texture2D，所以只会返回Texture2D类数据。另外，如果您感兴趣，这里有一个我为用多种纹理构建GUI库的小部件而设计的类。以防你需要经常做这种事情

using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using System.IO;

namespace Voodo.Utils {

    /// <summary>
    /// 
    /// </summary>
    public class TextureBaker {

        private readonly SpriteBatch _batch;
        private readonly RenderTarget2D _renderTarget;
        private readonly GraphicsDevice _graphicsDevice;

        /// <summary>
        /// 
        /// </summary>
        public Rectangle Bounds {
            get { return _renderTarget.Bounds; }
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="graphicsDevice"></param>
        /// <param name="size"></param>
        public TextureBaker(GraphicsDevice graphicsDevice, Vector2 size) {

            _graphicsDevice = graphicsDevice;

            _batch = new SpriteBatch(_graphicsDevice);
            _renderTarget = new RenderTarget2D(
                _graphicsDevice, 
                (int)size.X, 
                (int)size.Y);

            _graphicsDevice.SetRenderTarget(_renderTarget);

            _graphicsDevice.Clear(Color.Transparent);

            _batch.Begin(
                SpriteSortMode.Immediate, 
                BlendState.AlphaBlend, 
                SamplerState.LinearClamp,
                DepthStencilState.Default, 
                RasterizerState.CullNone);
        }

        #region Texture2D baking

        /// <summary>
        /// 
        /// </summary>
        /// <param name="texture"></param>
        public void BakeTexture(Texture2D texture) {

            _batch.Draw(
                texture,
                new Rectangle(0, 0, Bounds.Width, Bounds.Height), 
                Color.White);
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="texture"></param>
        /// <param name="destination"></param>
        public void BakeTexture(Texture2D texture, Rectangle destination) {

            _batch.Draw(
                texture,
                destination,
                Color.White);
        }        

        /// <summary>
        /// 
        /// </summary>
        /// <param name="texture"></param>
        /// <param name="destination"></param>
        /// <param name="source"></param>
        public void BakeTexture(Texture2D texture, Rectangle destination, Rectangle source) {

            _batch.Draw(
                texture,
                destination,
                source,
                Color.White);
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="texture"></param>
        /// <param name="sourceModification"></param>
        /// <param name="destination"></param>
        public void BakeTexture(Texture2D texture, System.Drawing.RotateFlipType sourceModification, Rectangle destination) {

            Stream sourceBuffer = new MemoryStream();
            texture.SaveAsPng(sourceBuffer, texture.Width, texture.Height);

            System.Drawing.Image sourceImage = System.Drawing.Image.FromStream(sourceBuffer);

            sourceBuffer = new MemoryStream();
            sourceImage.RotateFlip(sourceModification);
            sourceImage.Save(sourceBuffer, System.Drawing.Imaging.ImageFormat.Png);                       

            _batch.Draw(
                Texture2D.FromStream(_graphicsDevice, sourceBuffer),
                destination,
                Color.White);
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="texture"></param>
        /// <param name="sourceModification"></param>
        /// <param name="destination"></param>
        /// <param name="source"></param>
        public void BakeTexture(Texture2D texture, System.Drawing.RotateFlipType sourceModification, Rectangle destination, Rectangle source) {

            Stream sourceBuffer = new MemoryStream();
            texture.SaveAsPng(sourceBuffer, texture.Width, texture.Height);

            System.Drawing.Image sourceImage = System.Drawing.Image.FromStream(sourceBuffer);

            sourceBuffer = new MemoryStream();
            sourceImage.RotateFlip(sourceModification);
            sourceImage.Save(sourceBuffer, System.Drawing.Imaging.ImageFormat.Png);

            _batch.Draw(
                Texture2D.FromStream(_graphicsDevice, sourceBuffer),
                destination,
                source,
                Color.White);
        }

        #endregion

        #region SpriteFont baking

        /// <summary>
        /// 
        /// </summary>
        /// <param name="font"></param>
        /// <param name="text"></param>
        /// <param name="location"></param>
        /// <param name="textColor"></param>
        public void BakeText(SpriteFont font, string text, Vector2 location, Color textColor) {

            _batch.DrawString(font, text, location, textColor);
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="font"></param>
        /// <param name="text"></param>
        /// <param name="location"></param>
        public void BakeTextCentered(SpriteFont font, string text, Vector2 location, Color textColor) {

            var shifted = new Vector2 {
                X = location.X - font.MeasureString(text).X / 2,
                Y = location.Y - font.MeasureString(text).Y / 2
            };

            _batch.DrawString(font, text, shifted, textColor);
        }

        #endregion

        /// <summary>
        /// 
        /// </summary>
        /// <returns></returns>
        public Texture2D GetTexture() {

            _batch.End();
            _graphicsDevice.SetRenderTarget(null);

            return _renderTarget;
        }
    }
}

使用Microsoft.Xna.Framework；
使用Microsoft.Xna.Framework.Graphics；
使用System.IO；
命名空间Voodo.Utils{
/// 
/// 
/// 
公共类织纹机{
专用只读SpriteBatch\u批处理；
私有只读RenderTarget2D_renderTarget；
专用只读图形设备_GraphicsDevice；
/// 
/// 
/// 
公共矩形边界{
获取{return\u renderTarget.Bounds；}
}
/// 
/// 
/// 
/// 
/// 
公共纹理生成器（图形设备图形设备，矢量2大小）{
_graphicsDevice=graphicsDevice；
_批次=新的SpriteBatch（_graphicsDevice）；
_renderTarget=新建RenderTarget2D(
_图形设备，
（int）size.X，
（int）尺寸（Y）；
_graphicsDevice.SetRenderTarget（_renderTarget）；
_图形设备。清晰（颜色。透明）；
_批处理，开始(
SpriteSortMode。立即，
BlendState.AlphaBlend，
samplestate.LinearClamp，
DepthStencilState.Default，
光栅化状态（CullNone）；
}
#区域纹理2D烘焙
/// 
/// 
/// 
/// 
公共空间烘焙纹理（纹理2D纹理）{
_分批抽签(
纹理
新矩形（0，0，Bounds.Width，Bounds.Height），
颜色（白色）；
}
/// 
/// 
/// 
/// 
/// 
公共空心烘焙纹理（纹理2D纹理，矩形目标）{
_分批抽签(
纹理
目的地，
颜色（白色）；
}        
/// 
/// 
/// 
/// 
/// 
/// 
公共空心烘焙纹理（纹理2D纹理、矩形目标、矩形源）{
_分批抽签(
纹理
目的地，
来源:，
颜色（白色）；
}
/// 
/// 
/// 
///
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using System.IO;

namespace Voodo.Utils {

    /// <summary>
    /// 
    /// </summary>
    public class TextureBaker {

        private readonly SpriteBatch _batch;
        private readonly RenderTarget2D _renderTarget;
        private readonly GraphicsDevice _graphicsDevice;

        /// <summary>
        /// 
        /// </summary>
        public Rectangle Bounds {
            get { return _renderTarget.Bounds; }
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="graphicsDevice"></param>
        /// <param name="size"></param>
        public TextureBaker(GraphicsDevice graphicsDevice, Vector2 size) {

            _graphicsDevice = graphicsDevice;

            _batch = new SpriteBatch(_graphicsDevice);
            _renderTarget = new RenderTarget2D(
                _graphicsDevice, 
                (int)size.X, 
                (int)size.Y);

            _graphicsDevice.SetRenderTarget(_renderTarget);

            _graphicsDevice.Clear(Color.Transparent);

            _batch.Begin(
                SpriteSortMode.Immediate, 
                BlendState.AlphaBlend, 
                SamplerState.LinearClamp,
                DepthStencilState.Default, 
                RasterizerState.CullNone);
        }

        #region Texture2D baking

        /// <summary>
        /// 
        /// </summary>
        /// <param name="texture"></param>
        public void BakeTexture(Texture2D texture) {

            _batch.Draw(
                texture,
                new Rectangle(0, 0, Bounds.Width, Bounds.Height), 
                Color.White);
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="texture"></param>
        /// <param name="destination"></param>
        public void BakeTexture(Texture2D texture, Rectangle destination) {

            _batch.Draw(
                texture,
                destination,
                Color.White);
        }        

        /// <summary>
        /// 
        /// </summary>
        /// <param name="texture"></param>
        /// <param name="destination"></param>
        /// <param name="source"></param>
        public void BakeTexture(Texture2D texture, Rectangle destination, Rectangle source) {

            _batch.Draw(
                texture,
                destination,
                source,
                Color.White);
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="texture"></param>
        /// <param name="sourceModification"></param>
        /// <param name="destination"></param>
        public void BakeTexture(Texture2D texture, System.Drawing.RotateFlipType sourceModification, Rectangle destination) {

            Stream sourceBuffer = new MemoryStream();
            texture.SaveAsPng(sourceBuffer, texture.Width, texture.Height);

            System.Drawing.Image sourceImage = System.Drawing.Image.FromStream(sourceBuffer);

            sourceBuffer = new MemoryStream();
            sourceImage.RotateFlip(sourceModification);
            sourceImage.Save(sourceBuffer, System.Drawing.Imaging.ImageFormat.Png);                       

            _batch.Draw(
                Texture2D.FromStream(_graphicsDevice, sourceBuffer),
                destination,
                Color.White);
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="texture"></param>
        /// <param name="sourceModification"></param>
        /// <param name="destination"></param>
        /// <param name="source"></param>
        public void BakeTexture(Texture2D texture, System.Drawing.RotateFlipType sourceModification, Rectangle destination, Rectangle source) {

            Stream sourceBuffer = new MemoryStream();
            texture.SaveAsPng(sourceBuffer, texture.Width, texture.Height);

            System.Drawing.Image sourceImage = System.Drawing.Image.FromStream(sourceBuffer);

            sourceBuffer = new MemoryStream();
            sourceImage.RotateFlip(sourceModification);
            sourceImage.Save(sourceBuffer, System.Drawing.Imaging.ImageFormat.Png);

            _batch.Draw(
                Texture2D.FromStream(_graphicsDevice, sourceBuffer),
                destination,
                source,
                Color.White);
        }

        #endregion

        #region SpriteFont baking

        /// <summary>
        /// 
        /// </summary>
        /// <param name="font"></param>
        /// <param name="text"></param>
        /// <param name="location"></param>
        /// <param name="textColor"></param>
        public void BakeText(SpriteFont font, string text, Vector2 location, Color textColor) {

            _batch.DrawString(font, text, location, textColor);
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="font"></param>
        /// <param name="text"></param>
        /// <param name="location"></param>
        public void BakeTextCentered(SpriteFont font, string text, Vector2 location, Color textColor) {

            var shifted = new Vector2 {
                X = location.X - font.MeasureString(text).X / 2,
                Y = location.Y - font.MeasureString(text).Y / 2
            };

            _batch.DrawString(font, text, shifted, textColor);
        }

        #endregion

        /// <summary>
        /// 
        /// </summary>
        /// <returns></returns>
        public Texture2D GetTexture() {

            _batch.End();
            _graphicsDevice.SetRenderTarget(null);

            return _renderTarget;
        }
    }
}