XNA 消锯齿

这一阵子写程序，被人批评，这么大的锯齿。感觉很不爽，哎。

查了查，XNA是有个可以消锯齿的方法的。在XNA3.1的帮助里有关于消锯齿的一个范例

自己后来搜集了一些原理 参见这篇http://blog.csdn.net/xuehuic/article/details/5804213

 

相关内容 ：

(1)what is antialiasing?

Antialiasing is the process of softening hard edges in an image so that polygons appear less jagged.

Antialiasing is normally accomplished by multisampling, which means you use more than one pixel ("sample") from an image to determine the color of a pixel in your final image. The more samples per pixel, the smoother the resulting image.

Both PC and Xbox 360 platforms support Full Screen Antialiasing (FSAA) modes, where extra pixels are rendered to a render target and used as samples to create an antialiased final image. 4x FSAA uses four samples per pixel by rendering the scene to a render target with twice the height and width of the backbuffer. It uses the extra samples in the render target to create an antialiased final image. 2x FSAA is also common on PCs and supported by the Xbox 360.

Use the CheckDeviceMultiSampleType method to query for antialiasing support on your game machine. Also, use theMultiSampleQuality and MultiSampleType properties of thePresentationParameters to select an antialiasing mode for your backbuffer. For more information, seeHow To: Enable Antialiasing (Multisampling). You can set PreferMultiSampling on the GraphicsDeviceManager to true to let theGraphicsDeviceManager choose the antialiasing mode.

You can use the RenderState property MultiSampleAntiAlias to enable or disable multisampling at run time.

 

 

 

 

( 2)How To: Enable Antialiasing (Multisampling)

 

 

Demonstrates how to use the GraphicsDeviceManager to enable antialiasing for your game. TheCheckDeviceMultiSampleType method determines what kind of antialiasing your game computer supports.

Antialiasing is the process of smoothing the edges of triangles by averaging neighboring pixels in a render target. Because this process samples multiple pixels, it is also known as multisampling.

NoteEnabling antialiasing on the Xbox 360 will have a small performance impact. Enabling antialiasing on PCs may have a large impact on your game performance.

The Complete Sample

The code in this topic shows you the technique. You can download a complete code sample for this topic, including full source code and any additional supporting files required by the sample.

Download AntiAliasing_Sample.zip.

Using Antialiasing

To enable antialiasing in your game

• Set PreferMultiSampling to true in yourGame class constructor.

  This will default to MultiSampleType.TwoSamples on Xbox 360 (2x antialiasing). On a PC, theGraphicsDeviceManager will query forMultiSampleType.NonMaskable, and select that, if possible. Otherwise, it will choose the best available antialiasing.

  C# 

  graphics.PreferMultiSampling = true;

To customize antialiasing in your game

1. In your Game class constructor, add an event handler to thePreparingDeviceSettings event on yourGraphicsDeviceManager.

   If PreferMultiSampling is true, aMultiSampleType will be chosen automatically before the event is raised. Whether or not aMultiSampleType is chosen when the event is raised, you can use the event handler to query and choose your ownMultiSampleType.

   C# 

   public Game1(){    graphics = new GraphicsDeviceManager(this);    Content.RootDirectory = "Content";    graphics.PreferMultiSampling = true;    graphics.PreparingDeviceSettings +=      new EventHandler<PreparingDeviceSettingsEventArgs>(          graphics_PreparingDeviceSettings);}

2. Create a method to use as an event handler for thePreparingDeviceSettings event.

   You will be using the PreparingDeviceSettingsEventArgs instance to access thePresentationParameters and set your antialiasing preferences.

   C# 

   void graphics_PreparingDeviceSettings(object sender,     PreparingDeviceSettingsEventArgs e){

3. If your game is running on Xbox 360, set directly theMultiSampleQuality andMultiSampleType properties, and then return from your event handler.

   The Xbox supports MultiSampleType.TwoSamples andMultiSampleType.FourSamples, each with aMultiSampleQuality of 0 or 1.MultiSampleType.FourSamples is 4x antialiasing;MultiSampleType.TwoSamples is 2x antialiasing.

   C# 

               // Xbox 360 and most PCs support FourSamples/0             // (4x) and TwoSamples/0 (2x) antialiasing.            PresentationParameters pp =                 e.GraphicsDeviceInformation.PresentationParameters;#if XBOX            pp.MultiSampleQuality = 0;            pp.MultiSampleType = MultiSampleType.FourSamples;            return;#else

4. If your game is running on a PC, use CheckDeviceMultiSampleType to query for antialiasing support.

   Many PCs support 4x antialiasing, and most will support 2x antialiasing. Once you have determined that antialiasing is supported, set theMultiSampleType andMultiSampleQuality properties appropriately, and then return from the event handler.

   C# 

               int quality = 0;            GraphicsAdapter adapter = e.GraphicsDeviceInformation.Adapter;            SurfaceFormat format = adapter.CurrentDisplayMode.Format;            // Check for 4xAA            if (adapter.CheckDeviceMultiSampleType(DeviceType.Hardware, format,                false, MultiSampleType.FourSamples, out quality))            {                // even if a greater quality is returned, we only want quality 0                pp.MultiSampleQuality = 0;                pp.MultiSampleType =                    MultiSampleType.FourSamples;            }            // Check for 2xAA            else if (adapter.CheckDeviceMultiSampleType(DeviceType.Hardware,                 format, false, MultiSampleType.TwoSamples, out quality))            {                // even if a greater quality is returned, we only want quality 0                pp.MultiSampleQuality = 0;                pp.MultiSampleType =                    MultiSampleType.TwoSamples;            }            return;#endif
           }

   
   
   (3)
   PresentationParameters.MultiSampleType Property

   
   

   Gets or sets the multisample type.

   Namespace: Microsoft.Xna.Framework.Graphics
   Assembly: Microsoft.Xna.Framework (in microsoft.xna.framework.dll

   C# 

   public MultiSampleType MultiSampleType { get; set; }

   Property Value

   The multisample type. Must be MultiSampleType.None unlessSwapEffect has been set to SwapEffect.Discard. Multisampling is supported only ifSwapEffect is SwapEffect.Discard.

   (4)

   PresentationParameters.MultiSampleQuality Property
   

   
   

   Gets or sets a value indicating the multisample quality level.

   Namespace: Microsoft.Xna.Framework.Graphics
   Assembly: Microsoft.Xna.Framework (in microsoft.xna.framework.dll)

   C# 

   public int MultiSampleQuality { get; set; }

   Property Value

   The multisample quality level. The valid range is from 0 to one less than the value returned byCheckDeviceMultiSampleType.

   Paired values of render targets or of depth-stencil surfaces and MultiSampleType must match.

    

   其它相关内容不做赘述 ，附上范例的源代码此代码为Game1.cs中的代码：

   
   

   #region File Description//-----------------------------------------------------------------------------// Game1.cs//// Microsoft XNA Community Game Platform// Copyright (C) Microsoft Corporation. All rights reserved.//-----------------------------------------------------------------------------#endregionusing System;using System.Collections.Generic;using Microsoft.Xna.Framework;using Microsoft.Xna.Framework.GamerServices;using Microsoft.Xna.Framework.Graphics;using Microsoft.Xna.Framework.Input;namespace AntiAliasing{ /// <summary> /// This is the main type for your game /// </summary> public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; graphics.PreferMultiSampling = true; graphics.PreparingDeviceSettings += new EventHandler<PreparingDeviceSettingsEventArgs>( graphics_PreparingDeviceSettings); } void graphics_PreparingDeviceSettings(object sender, PreparingDeviceSettingsEventArgs e) { // Xbox 360 and most PCs support FourSamples/0 // (4x) and TwoSamples/0 (2x) antialiasing. PresentationParameters pp = e.GraphicsDeviceInformation.PresentationParameters; int quality = 0; GraphicsAdapter adapter = e.GraphicsDeviceInformation.Adapter; SurfaceFormat format = adapter.CurrentDisplayMode.Format; // Check for 4xAA if (adapter.CheckDeviceMultiSampleType(DeviceType.Hardware, format, false, MultiSampleType.FourSamples, out quality)) { // even if a greater quality is returned, we only want quality 0 pp.MultiSampleQuality = 0; pp.MultiSampleType = MultiSampleType.FourSamples; } // Check for 2xAA else if (adapter.CheckDeviceMultiSampleType(DeviceType.Hardware, format, false, MultiSampleType.TwoSamples, out quality)) { // even if a greater quality is returned, we only want quality 0 pp.MultiSampleQuality = 0; pp.MultiSampleType = MultiSampleType.TwoSamples; } return; } /// <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); // TODO: Load your game content here } 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(); // TODO: Add your update logic here 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) { graphics.GraphicsDevice.Clear(Color.CornflowerBlue); // TODO: Add your drawing code here base.Draw(gameTime); } }} 

    

    

   不过我比较笨 ，最后用了一个超easy的方法，就是直接把图片做成羽化后的图片就可以了 O(∩_∩)O~

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隔了5个月后我再来看这个资料，补充一条。

当做测试时，如果出现找不到合适的图形卡，请检查设置参数是否正确，请检查shader版本等这些提示问题，应该是高估显卡的性能了。

一般显卡支持4X抗锯齿，质量从0-10不等，但一般选0就好了，就最好了。

 

然后模型上的锯齿还是很明显，目前还没有搞出来，等我搞出来再补上说明。

 

 

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好 隔了半个月，我搞清楚了为什么我的3D模型那么大的锯齿了，原因在于画法不一样，我一直是使用3D模型先画到一个贴图上，再画的贴图，也许3D和2D的抗锯齿效果是有些差别的，即使我全开了4X还是有很明显的锯齿，但是当我直接画3D模型的时候，啧啧，锯齿就小了很多，所有感悟：程序员要敢于打破自己的原有思路，才能有进步。

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好了又隔了一段时间，我又发现rendertarget实际上是有个抗锯齿重载的，汗颜。。。另外如果加了shader的话，要注意shader里面的内容是否有抗锯齿，或者加了锯齿的语句。