Question

我想在Windows Phone 7 XNA应用程序中使用RenderTarget2D。但是，我没有成功，因为将绘图切换到我的渲染目标，然后切换回（通过使用SetRenderTarget（null））会导致我的WHOLE屏幕以蓝色绘制，从而覆盖在切换到渲染目标之前绘制的任何内容。我不确定这是否是预期的行为。

实际上，重现此行为非常容易。只需为Windows Phone 7创建一个简单的XNA游戏并使用此代码：

protected override void Draw(GameTime gameTime)
{
   spriteBatch.Begin();
   spriteBatch.Draw(textureBackground, new Vector2(0,0), Color.White); // This is a 480x800 image and my resolution is set to 480x800
   spriteBatch.End(); // Testing this block of code confirms that the textureBackground is being drawn

   graphics.GraphicsDevice.SetRenderTarget(textureBuffer);

   spriteBatch.Begin();
   spriteBatch.Draw(textureSummer, new Vector2(0, 0), Color.White); // texture Summer is a 20x20 pixels texture while the screen resolution is 480 x 800
   spriteBatch.End();

   graphics.GraphicsDevice.SetRenderTarget(null); // switch back 

   spriteBatch.Begin();
   spriteBatch.Draw(textureBuffer, new Vector2(0,0), Color.White);
   spriteBatch.End(); // at this point, textureBuffer is drawn (the 20x20 pixeles image) in the upper left hand corner but the background of the whole screen is BLUE and so textureBackground texture has been overwritten by this color and is not showing anymore.

   // At this point all I see is a blue background with a 20x20 pixels image in the upper left hand corner.
}

我正在创建渲染目标，如下所示：

textureSummer = Content.Load<Texture2D>("summer_picture_icon"); // the 20x20 pixels texture
textureBuffer = new RenderTarget2D(graphics.GraphicsDevice, textureSummer.Width, textureSummer.Height); // the RenderTarget2D object. Note that this RenderTarget is only 20x20.

因此，我做错了什么？

感谢。

Answer 1

“问题”是你首先绘制背景，然后更改rendertarget，然后渲染那个小方块，然后更改rendertarget，然后再次绘制小方块。按此顺序：

渲染屏幕内容
Rendertarget Change
渲染屏幕外的内容
Rendertarget Change
渲染屏幕内容

rendertarget的每次更改都会清除它。

你应该做什么;

Rendertarget Change
渲染屏幕外的内容
Rendertarget Change
渲染屏幕内容

像这样：

GraphicsDevice.SetRenderTarget(textureBuffer);

spriteBatch.Begin();
spriteBatch.Draw(textureSummer, new Vector2(0, 0), Color.White); // texture Summer is a 20x20 pixels texture while the screen resolution is 480 x 800
spriteBatch.End();

GraphicsDevice.SetRenderTarget(null); // switch back 

spriteBatch.Begin();
spriteBatch.Draw(textureBackground, new Vector2(0,0), Color.White); // This is a 480x800 image and my resolution is set to 480x800
spriteBatch.Draw(textureBuffer, new Vector2(0,0), Color.White);
spriteBatch.End();

Windows Phone中的XNA RenderTarget2D

1 个答案: