仿制shazzam的简单功能，将hlsl转换为WPF中的ShaderEffect

(此文章只是在对WPF的Effect产生兴趣才稍微研究了一点后面的知识;需要了解更多可参考archive.codeplex.com/?p=shazzam的源代码以及WPF基础知识)

WPF Shader 基础

1. blend中的特效
   之前一直使用blend里自带的几个特效，突然有一天比较好奇这些特效是怎么来的。然后就听说了shazzam并看到更多的特效

2. shazzam的代码
   在参考网址下载了shazzam的代码来研究研究，只抽取出里面【如何将.fx文件编译为.ps，再产生一个调用.ps文件的.cs文件,然后就可以像正常使用其它自带Effect一样使用了】这一过程

3. HLSL语法
   网上有很多教程啊，目前就直接拿一些写好的来用就行，一个简单的ToonShader.fx

   /// <description>An effect that applies cartoon-like shading (posterization).</description>
   
   sampler2D inputSampler : register(S0);
   
   //-----------------------------------------------------------------------------------------
   // Shader constant register mappings (scalars - float, double, Point, Color, Point3D, etc.)
   //-----------------------------------------------------------------------------------------
   
   /// <summary>The number of color levels to use.</summary>
   /// <minValue>3</minValue>
   /// <maxValue>15</maxValue>
   /// <defaultValue>5</defaultValue>
   float Levels : register(C0);
   
   float4 main(float2 uv : TEXCOORD) : COLOR
   {
       float4 color = tex2D( inputSampler, uv );
       color.rgb /= color.a;
   
       int levels = floor(Levels);
       color.rgb *= levels;
       color.rgb = floor(color.rgb);
       color.rgb /= levels;
       color.rgb *= color.a;
       return color;
   }
   

4. ShaderCompiler
   利用dxd的D3DXCompileShader将.fx文件转换为.ps文件

   public void Compile(string codeText, string output, string fxName, ShaderProfileshaderProfile = ShaderProfile.ps_2_0)
   {
       IsCompiled = false;
       string path = output;
       IntPtr defines = IntPtr.Zero;
       IntPtr includes = IntPtr.Zero;
       IntPtr ppConstantTable = IntPtr.Zero;
       string methodName = "main";
       string targetProfile2 = "ps_2_0";
       targetProfile2 = ((shaderProfile != ShaderProfile.ps_3_0) ? "ps_2_0" : "ps_3_0");
       bool useDx10 = false;
       int hr2 = 0;
       ID3DXBuffer ppShader2;
       ID3DXBuffer ppErrorMsgs2;
       if (!useDx10)
       {
           hr2 = ((IntPtr.Size != 8) ?
               DxHelper.D3DXCompileShader(codeText, codeText.Length, defines, includes,methodName, targetProfile2, 0, out ppShader2, out ppErrorMsgs2, outppConstantTable)
               :
               DxHelper.D3DXCompileShader64Bit(codeText, codeText.Length, defines, includes,methodName, targetProfile2, 0, out ppShader2, out ppErrorMsgs2, outppConstantTable));
       }
       else
       {
           int pHr = 0;
           hr2 = DxHelper.D3DX10CompileFromMemory(codeText, codeText.Length, string.Empty,IntPtr.Zero, IntPtr.Zero, methodName, targetProfile2, 0, 0, IntPtr.Zero, outppShader2, out   ppErrorMsgs2, ref pHr);
       }
       if (hr2 != 0)
       {
           IntPtr errors = ppErrorMsgs2.GetBufferPointer();
           ppErrorMsgs2.GetBufferSize();
           ErrorText = Marshal.PtrToStringAnsi(errors);
           IsCompiled = false;
       }
       else
       {
           ErrorText = "";
           IsCompiled = true;
           string psPath = path + fxName;
           IntPtr pCompiledPs = ppShader2.GetBufferPointer();
           int compiledPsSize = ppShader2.GetBufferSize();
           byte[] compiledPs = new byte[compiledPsSize];
           Marshal.Copy(pCompiledPs, compiledPs, 0, compiledPs.Length);
           using (FileStream psFile = File.Open(psPath, FileMode.Create, FileAccess.Write))
           {
               psFile.Write(compiledPs, 0, compiledPs.Length);
           }
       }
       if (ppShader2 != null)
       {
           Marshal.ReleaseComObject(ppShader2);
       }
       ppShader2 = null;
       if (ppErrorMsgs2 != null)
       {
           Marshal.ReleaseComObject(ppErrorMsgs2);
       }
       ppErrorMsgs2 = null;
       CompileFinished();
   }
   

5. CodeGenerator
   生成引用.ps文件的effect.cs文件

   private static string GenerateCode(CodeDomProvider provider, CodeCompileUnit compileUnit)
   {
       // Generate source code using the code generator.
       using (StringWriter writer = new StringWriter())
       {
           string indentString = IndentUsingTabs ? "\t" : String.Format("{0," + IndentSpaces.ToString() + "}", " ");
           CodeGeneratorOptions options = new CodeGeneratorOptions { IndentString = indentString, BlankLinesBetweenMembers = true, BracingStyle = "C" };
           provider.GenerateCodeFromCompileUnit(compileUnit, writer, options);
           string text = writer.ToString();
           // Fix up code: make static DP fields readonly, and use triple-slash or triple-quote comments for XML doc comments.
           if (provider.FileExtension == "cs")
           {
               text = text.Replace("public static DependencyProperty", "public static readonly DependencyProperty");
               text = Regex.Replace(text, @"// <(?!/?auto-generated)", @"/// <");
           }
           else
               if (provider.FileExtension == "vb")
           {
               text = text.Replace("Public Shared ", "Public Shared ReadOnly ");
               text = text.Replace("'<", "'''<");
           }
           return text;
       }
   }
   

生成的cs文件内容如下：

``` CS
//------------------------------------------------------------------------------
// <auto-generated>
//     此代码由工具生成。
//     运行时版本:4.0.30319.42000
//
//     对此文件的更改可能会导致不正确的行为，并且如果
//     重新生成代码，这些更改将会丢失。
// </auto-generated>
//------------------------------------------------------------------------------

using System;
using System.ComponentModel;
using System.Windows;
using System.Windows.Media;
using System.Windows.Media.Effects;
using System.Windows.Media.Media3D;

namespace ShaderPan
{
    /// <summary>An effect that applies cartoon-like shading (posterization).</summary>
    public class ToonShaderEffect : ShaderEffect
    {

        public static readonly DependencyProperty InputProperty = ShaderEffect.RegisterPixelShaderSamplerProperty("Input", typeof(ToonShaderEffect), 0);

        public static readonly DependencyProperty LevelsProperty = DependencyProperty.Register("Levels", typeof(double), typeof(ToonShaderEffect), new UIPropertyMetadata   (((double)(5D)), PixelShaderConstantCallback(0)));

        public ToonShaderEffect()
        {
            PixelShader pixelShader = new PixelShader();
            pixelShader.UriSource = new Uri("C:\\Users\\Administrator\\Desktop\\WpfTPL\\shader\\ToonShader.ps", UriKind.Absolute);
            this.PixelShader = pixelShader;

            this.UpdateShaderValue(InputProperty);
            this.UpdateShaderValue(LevelsProperty);
        }

        public Brush Input
        {
            get
            {
                return ((Brush)(this.GetValue(InputProperty)));
            }
            set
            {
                this.SetValue(InputProperty, value);
            }
        }

        /// <summary>The number of color levels to use.</summary>
        public double Levels
        {
            get
            {
                return ((double)(this.GetValue(LevelsProperty)));
            }
            set
            {
                this.SetValue(LevelsProperty, value);
            }
        }
    }
}
```

6. ShaderPanTest
测试功能--运用C#动态编译生成来使用Effect

``` CS
public static Assembly CompileInMemory(string code)
{
    var provider = new CSharpCodeProvider(new Dictionary<string, string>() { { "CompilerVersion", "v4.0" } });
    CompilerParameters options = new CompilerParameters();
    options.ReferencedAssemblies.Add("System.dll");
    options.ReferencedAssemblies.Add("System.Core.dll");
    options.ReferencedAssemblies.Add("WindowsBase.dll");
    options.ReferencedAssemblies.Add("PresentationFramework.dll");
    options.ReferencedAssemblies.Add("PresentationCore.dll");
    options.IncludeDebugInformation = false;
    options.GenerateExecutable = false;
    options.GenerateInMemory = true;
    CompilerResults results = provider.CompileAssemblyFromSource(options, code);
    provider.Dispose();
    if (results.Errors.Count == 0)
        return results.CompiledAssembly;
    else
        return null;
}
```

7. 源码

（exe图标来自easyicon）
lenkaset/lkts_WPFPixelShader (gitee.com)