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[ShaderGraph]添加自定义Pass

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作者 Jauved
4 分钟阅读
[ShaderGraph]添加自定义Pass

[ShaderGraph]添加自定义Pass

00 处理

00a 自定义Pass

仿照开关内置Pass的方式, 添加一个自定义Pass, 同时添加开关.

添加Pass可以仿照ShaderGraph自身Pass的写法如下:

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public static PassDescriptor CrossSection(UniversalTarget target)
{
    var result = new PassDescriptor()
    {
        // Definition
        displayName = "CrossSection",
        // 这个地方是用来做比较进行一些宏定义的, 文件在
        // Library/PackageCache/com.unity.render-pipelines.universal@12.1.10/Editor/ShaderGraph/Includes/ShaderPass.hlsl
        // 如果你写自己的, 但是又没有在文件中, 默认第一个是SHADERPASS_FORWARD, 会导致光照相关的参数没有, 会报错
        referenceName = "SHADERPASS_UNLIT",
        lightMode = "CrossSection",
        useInPreview = true,

        // Template
        passTemplatePath = UniversalTarget.kUberTemplatePath,
        sharedTemplateDirectories = UniversalTarget.kSharedTemplateDirectories,

        // Port Mask
        validVertexBlocks = CoreBlockMasks.Vertex,
        validPixelBlocks = ExternalBlockMasks.FragmentCrossSection,

        // Fields
        structs = CoreStructCollections.Default,
        fieldDependencies = CoreFieldDependencies.Default,

        // Conditional State
        renderStates = ExternalRenderState.CrossSection(target),
        pragmas = CorePragmas.Instanced,
        defines = new DefineCollection(),
        keywords = new KeywordCollection(),
        includes = ExternalLitIncludes.CrossSection,

        // Custom Interpolator Support
        customInterpolators = CoreCustomInterpDescriptors.Common
    };

    ExtendedPasses.AddAlphaClipControlToPassMultiCompile(ref result, target);

    return result;
}

需要注意的是

  • referenceName = "SHADERPASS_UNLIT", referenceName是用来定义一些宏的开关的, 此处可以选择的值在Library/PackageCache/com.unity.render-pipelines.universal@12.1.10/Editor/ShaderGraph/Includes/ShaderPass.hlsl文件中, 如下:

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    #ifndef UNIVERSAL_SHADERPASS_INCLUDED
#define UNIVERSAL_SHADERPASS_INCLUDED
  
#define SHADERPASS_FORWARD (0)
#define SHADERPASS_GBUFFER (1)
#define SHADERPASS_DEPTHONLY (2)
#define SHADERPASS_SHADOWCASTER (3)
#define SHADERPASS_META (4)
#define SHADERPASS_2D (5)
#define SHADERPASS_UNLIT (6)
#define SHADERPASS_SPRITELIT (7)
#define SHADERPASS_SPRITENORMAL (8)
#define SHADERPASS_SPRITEFORWARD (9)
#define SHADERPASS_SPRITEUNLIT (10)
#define SHADERPASS_DEPTHNORMALSONLY (11)
#define SHADERPASS_DBUFFER_PROJECTOR (12)
#define SHADERPASS_DBUFFER_MESH (13)
#define SHADERPASS_FORWARD_EMISSIVE_PROJECTOR (14)
#define SHADERPASS_FORWARD_EMISSIVE_MESH (15)
#define SHADERPASS_FORWARD_PREVIEW (16)
#define SHADERPASS_DECAL_SCREEN_SPACE_PROJECTOR (17)
#define SHADERPASS_DECAL_SCREEN_SPACE_MESH (18)
#define SHADERPASS_DECAL_GBUFFER_PROJECTOR (19)
#define SHADERPASS_DECAL_GBUFFER_MESH (20)
#define SHADERPASS_DEPTHNORMALS (21)
#endif

    如果要根据你自己的定义去对Library/PackageCache/com.unity.render-pipelines.universal@12.1.10/Editor/ShaderGraph/Includes/Varyings.hlsl做一些操作, 那么才需要添加, 否则使用现有的即可. 具体这些关键字的开关, 可以在Varyings.hlsl文件中去确认.

  • lightMode = "CrossSection",这个是用来在做RendererFeature的时候用来指定LightMode的, 需要保持一致.

  • validPixelBlocks = ExternalBlockMasks.FragmentCrossSection,这里只需要传递你要用到的中间变量即可. 比如我只需要用到的是:

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    public static readonly BlockFieldDescriptor[] FragmentCrossSection = new BlockFieldDescriptor[]
{
    ExtensionBlockFields.SurfaceDescription.CrossSectionColor,
    BlockFields.SurfaceDescription.Alpha,
    BlockFields.SurfaceDescription.AlphaClipThreshold,
};

  • renderStates = ExternalRenderState.CrossSection(target),, 这里是定义ZTest, ZWrite, Cull之类的, 按照需求定义即可

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    public static RenderStateCollection CrossSection(UniversalTarget target)
{
    var result = new RenderStateCollection
    {
        { RenderState.ZTest(ZTest.LEqual) },
        { RenderState.ZWrite(ZWrite.On) },
        { RenderState.Cull(Cull.Front) },
    };
  
    return result;
}

  • includes = ExternalLitIncludes.CrossSection,这一行用来引用外部的hlsl, 具体定义如下, 这样就可以自己去写对应的hlsl文件.

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    private const string kCrossSectionPass =
           "Packages/xxxx/ShaderLibrary/CrossSectionPass.hlsl";
public static readonly IncludeCollection CrossSection = new IncludeCollection
{
   // Pre-graph
   { CoreIncludes.CorePregraph },
   { CoreIncludes.ShaderGraphPregraph },
  
   // Post-graph
   { CoreIncludes.CorePostgraph },
   { kCrossSectionPass, IncludeLocation.Postgraph },
};

    自定义的hlsl文件可以仿照Library/PackageCache/com.unity.render-pipelines.universal@12.1.10/Editor/ShaderGraph/Includes中的hlsl文件, 例子如下:

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    #ifndef SG_CROSS_SECTION_PASS_INCLUDED
#define SG_CROSS_SECTION_PASS_INCLUDED
  
PackedVaryings vert(Attributes input)
{
    Varyings output = (Varyings)0;
    output = BuildVaryings(input);
    PackedVaryings packedOutput = (PackedVaryings)0;
    packedOutput = PackVaryings(output);
    return packedOutput;
}
  
half4 frag(PackedVaryings packedInput) : SV_TARGET
{
    Varyings unpacked = UnpackVaryings(packedInput);
    UNITY_SETUP_INSTANCE_ID(unpacked);
    UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(unpacked);
    SurfaceDescription surfaceDescription = BuildSurfaceDescription(unpacked);
  
    #if _ALPHATEST_ON
    half alpha = surfaceDescription.Alpha;
    clip(alpha - surfaceDescription.AlphaClipThreshold);
    #else
    half alpha = 1.h;
    #endif
  
    half4 color = half4(surfaceDescription.CrossSectionColor,alpha);
  
    return 0;
}
  
#endif

00b 在SubShader中调用Pass

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public static SubShaderDescriptor VehicleLitGLESSubShader(UniversalTarget target, WorkflowMode workflowMode,
            string renderType, string renderQueue, bool complexLit,
            SubShaderOptions options)
{
    ...

    if (options.crossSectionPassOn)
        result.passes.Add(SubShaderUtils.PassVariant(ExtendedPasses.CrossSection(target),
            ExtendedPragmas.ExtendedDefault));

    return result;
}

参考网页

URP, ShaderGraph
URP ShaderGraph 定制 自定义Pass Pass
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