Unity Built-in Shader转URP Shader 接口查询对照表

本篇文章转自Teofilo Dutra编写的《From Built-in to URP》，其中有很多在写URP管线Shader时需要用到的函数，作为备忘速查表非常实用，所以记录于此。本文经过精简和翻译，不一定适用于大家，可以点击上方链接跳转至作者原文。本文是基于7.3版本的URP编写的，有些暂时还不支持的内容可能在后续版本更新迭代。

结构

首先要在SubShader的Tags中添加”RenderPipeline” = “UniversalPipeline”，并且使用HLSL的宏代替旧版的CG语言宏。

Built-in	URP
CGPROGRAM / HLSLPROGRAM	HLSLPROGRAM
ENDCG / ENDHLSL	ENDHLSL
CGINCLUDE / HLSLINCLUDE	HLSLINCLUDE

Include文件的改动

Content	Built-in	URP
Core	Unity.cginc	Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl
Light	AutoLight.cginc	Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl
Shadows	AutoLight.cginc	Packages/com.unity.render-pipelines.universal/ShaderLibrary/Shadows.hlsl
Surface shaders	Lighting.cginc	无

其他常用的include文件:

Packages/com.unity.render-pipelines.core/ShaderLibrary/SpaceTransforms.hlsl
Packages/com.unity.render-pipelines.universal/ShaderLibrary/ShaderVariablesFunctions.hlsl
Packages/com.unity.render-pipelines.core/ShaderLibrary/Common.hlsl
Packages/com.unity.render-pipelines.universal/ShaderLibrary/Input.hlsl
Packages/com.unity.render-pipelines.core/ShaderLibrary/Color.hlsl
Packages/com.unity.render-pipelines.universal/ShaderLibrary/DeclareDepthTexture.hlsl
Packages/com.unity.render-pipelines.universal/ShaderLibrary/DeclareOpaqueTextue.hlsl

光照模式

Built-in	URP
ForwardBase	UniversalForward
ForwardAdd	无
Deferred and related	UniversalGBuffer seems to have just been added to URP
Vertex and related	无
ShadowCaster	ShadowCaster
MotionVectors	暂不支持

URP其他支持的光照模式：

DepthOnly
Meta (用于烘焙光照贴图)
Universal2D

变体(Variants)

URP支持着色器的变体，可以使用#pragma multi_compile宏实现编译不同需求下的着色器，常见的内置关键字有：

_MAIN_LIGHT_SHADOWS
_MAIN_LIGHT_SHADOWS_CASCADE
_ADDITIONAL_LIGHTS_VERTEX
_ADDITIONAL_LIGHTS
_ADDITIONAL_LIGHT_SHADOWS
_SHADOWS_SOFT
_MIXED_LIGHTING_SUBTRACTIVE

预定义的着色器预处理宏

辅助宏(Helpers)

Built-in	URP
UNITY_PROJ_COORD(a)	无，使用 a.xy/a.w 来代替
UNITY_INITIALIZE_OUTPUT(type, name)	ZERO_INITIALIZE(type, name)

阴影贴图

需要包含 Packages/com.unity.render-pipelines.universal/ShaderLibrary/Shadows.hlsl

Built-in	URP
UNITY_DECLARE_SHADOWMAP(tex)	TEXTURE2D_SHADOW_PARAM(textureName, samplerName)
UNITY_SAMPLE_SHADOW(tex, uv)	SAMPLE_TEXTURE2D_SHADOW(textureName, samplerName, coord3)
UNITY_SAMPLE_SHADOW_PROJ(tex, uv)	SAMPLE_TEXTURE2D_SHADOW(textureName, samplerName, coord4.xyz/coord4.w)

纹理/采样器的声明宏

Built-in	URP
UNITY_DECLARE_TEX2D(name)	TEXTURE2D(textureName); SAMPLER(samplerName);
UNITY_DECLARE_TEX2D_NOSAMPLER(name)	TEXTURE2D(textureName);
UNITY_DECLARE_TEX2DARRAY(name)	TEXTURE2D_ARRAY(textureName); SAMPLER(samplerName);
UNITY_SAMPLE_TEX2D(name, uv)	SAMPLE_TEXTURE2D(textureName, samplerName, coord2)
UNITY_SAMPLE_TEX2D_SAMPLER(name, samplername, uv)	SAMPLE_TEXTURE2D(textureName, samplerName, coord2)
UNITY_SAMPLE_TEX2DARRAY(name, uv)	SAMPLE_TEXTURE2D_ARRAY(textureName, samplerName, coord2, index)
UNITY_SAMPLE_TEX2DARRAY_LOD(name, uv, lod)	SAMPLE_TEXTURE2D_ARRAY_LOD(textureName, samplerName, coord2, index, lod)

内置的着色器辅助函数

可以在 Packages/com.unity.render-pipelines.core/ShaderLibrary/SpaceTransforms.hlsl 看到下方的所有函数

顶点变换函数

Built-in	URP
float4 UnityObjectToClipPos(float3 pos)	float4 TransformObjectToHClip(float3 positionOS)
float3 UnityObjectToViewPos(float3 pos)	TransformWorldToView(TransformObjectToWorld(positionOS))

泛用的辅助函数

Built-in	URP	Include
float3 WorldSpaceViewDir (float4 v)	float3 GetWorldSpaceViewDir(float3 positionWS)	Include “Packages/com.unity.render-pipelines.universal/ShaderLibrary/ShaderVariablesFunctions.hlsl”
float3 ObjSpaceViewDir (float4 v)	无，使用 TransformWorldToObject(GetCameraPositionWS()) - objectSpacePosition;
float2 ParallaxOffset (half h, half height, half3 viewDir)	可能没有，从 UnityCG.cginc 复制
fixed Luminance (fixed3 c)	real Luminance(real3 linearRgb)	Include “Packages/com.unity.render-pipelines.core/ShaderLibrary/Color.hlsl”
fixed3 DecodeLightmap (fixed4 color)	real3 DecodeLightmap(real4 encodedIlluminance, real4 decodeInstructions)	Include “Packages/com.unity.render-pipelines.core/ShaderLibrary/EntityLighting.hlsl” URP中decodeInstructions 为 half4(LIGHTMAP_HDR_MULTIPLIER, LIGHTMAP_HDR_EXPONENT, 0.0h, 0.0h)
float4 EncodeFloatRGBA (float v)	可能没有，从 UnityCG.cginc 复制
float DecodeFloatRGBA (float4 enc)	可能没有，从 UnityCG.cginc 复制
float2 EncodeFloatRG (float v)	可能没有，从 UnityCG.cginc 复制
float DecodeFloatRG (float2 enc)	可能没有，从 UnityCG.cginc 复制
float2 EncodeViewNormalStereo (float3 n)	可能没有，从 UnityCG.cginc 复制
float3 DecodeViewNormalStereo (float4 enc4)	可能没有，从 UnityCG.cginc 复制

前向渲染辅助函数

Built-in	URP	Include
float3 WorldSpaceLightDir (float4 v)	_MainLightPosition.xyz - TransformObjectToWorld(objectSpacePosition)	Include “Packages/com.unity.render-pipelines.universal/ShaderLibrary/Input.hlsl”
float3 ObjSpaceLightDir (float4 v)	TransformWorldToObject(_MainLightPosition.xyz) - objectSpacePosition	Include “Packages/com.unity.render-pipelines.universal/ShaderLibrary/Input.hlsl”
float3 Shade4PointLights (…)	无，可尝试用half3 VertexLighting(float3 positionWS, half3 normalWS)	include “Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl”

屏幕空间辅助函数

Built-in	URP	Include
float4 ComputeScreenPos (float4 clipPos)	float4 ComputeScreenPos(float4 positionCS)	Include “Packages/com.unity.render-pipelines.universal/ShaderLibrary/ShaderVariablesFunctions.hlsl”
float4 ComputeGrabScreenPos (float4 clipPos)	无

顶点光照的辅助函数

Built-in	URP	Include
float3 ShadeVertexLights (float4 vertex, float3 normal)	无，可尝试用 UNITY_LIGHTMODEL_AMBIENT.xyz + VertexLighting(…)	include “Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl”

可以在 Packages/com.unity.render-pipelines.core/ShaderLibrary/Common.hlsl 中找到一些通用函数

内置的着色器变量

Built-in	URP	Include
_LightColor0	_MainLightColor	Include “Packages/com.unity.render-pipelines.universal/ShaderLibrary/Input.hlsl”
_WorldSpaceLightPos0	_MainLightPosition	Include “Packages/com.unity.render-pipelines.universal/ShaderLibrary/Input.hlsl”
_LightMatrix0	可能还不支持
unity_4LightPosX0, unity_4LightPosY0, unity_4LightPosZ0	URP中，额外的灯光存储在一个数组或缓冲中(取决于平台),使用Light GetAdditionalLight(uint i, float3 positionWS)获取光照信息	Include “Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl”
unity_4LightAtten0	URP中，额外的灯光存储在一个数组或缓冲中(取决于平台),使用Light GetAdditionalLight(uint i, float3 positionWS)获取光照信息	Include “Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl”
unity_LightColor	URP中，额外的灯光存储在一个数组或缓冲中(取决于平台),使用Light GetAdditionalLight(uint i, float3 positionWS)获取光照信息	Include “Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl”
unity_WorldToShadow	float4x4 _MainLightWorldToShadow[MAX_SHADOW_CASCADES + 1] or _AdditionalLightsWorldToShadow[MAX_VISIBLE_LIGHTS]	Include “Packages/com.unity.render-pipelines.universal/ShaderLibrary/Shadows.hlsl”

可以使用GetAdditionalLight(…)获取额外的光源，也可以使用GetAdditionalLightsCount()查询额外的光源数量。

其他方法

阴影

更多阴影相关函数可以查看 Packages/com.unity.render-pipelines.universal/ShaderLibrary/Shadows.hlsl

Built-in	URP
UNITY_SHADOW_COORDS(x)	可能没有，可以写作float4 shadowCoord : TEXCOORD0;
TRANSFER_SHADOW(a)	a.shadowCoord = TransformWorldToShadowCoord(worldSpacePosition)
SHADOWS_SCREEN	暂不支持

雾

更多雾相关的函数可以查看 Packages/com.unity.render-pipelines.universal/ShaderLibrary/ShaderVariablesFunctions.hlsl

Built-in	URP
UNITY_FOG_COORDS(x)	可能没有，可以写作float fogCoord : TEXCOORD0;
UNITY_TRANSFER_FOG(o, outpos)	o.fogCoord = ComputeFogFactor(clipSpacePosition.z);
UNITY_APPLY_FOG(coord, col)	color = MixFog(color, i.fogCoord);

深度

可以包含 “Packages/com.unity.render-pipelines.universal/ShaderLibrary/DeclareDepthTexture.hlsl” 并使用 _CameraDepthTexture来调用深度纹理。也可以使用SampleSceneDepth(…) 和 LoadSceneDepth(…)。

Built-in	URP	Include
LinearEyeDepth(sceneZ)	LinearEyeDepth(sceneZ, _ZBufferParams)	Include “Packages/com.unity.render-pipelines.core/ShaderLibrary/Common.hlsl”
Linear01Depth(sceneZ)	Linear01Depth(sceneZ, _ZBufferParams)	Include “Packages/com.unity.render-pipelines.core/ShaderLibrary/Common.hlsl”

其他

Built-in	URP	Include
ShadeSH9(normal)	SampleSH(normal)	Include “Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl”
unity_ColorSpaceLuminance	无，使用Luminance()	Include “Packages/com.unity.render-pipelines.core/ShaderLibrary/Color.hlsl”

后期/特效

URP不支持OnPreCull, OnPreRender, OnPostRender 和 OnRenderImage. 支持 OnRenderObject 和 OnWillRenderObject。RenderPipelineManager提供了渲染管线中注入的位置：

beginCameraRendering(ScriptableRenderContext context, Camera camera)
endCameraRendering(ScriptableRenderContext context, Camera camera)
beginFrameRendering(ScriptableRenderContext context,Camera[] cameras)
endFrameRendering(ScriptableRenderContext context,Camera[] cameras)

例如：

void OnEnable()
{RenderPipelineManager.beginCameraRendering += MyCameraRendering;
}void OnDisable()
{RenderPipelineManager.beginCameraRendering -= MyCameraRendering;
}void MyCameraRendering(ScriptableRenderContext context, Camera camera)
{...if(camera == myEffectCamera){...UniversalRenderPipeline.RenderSingleCamera(context, camera);}...
}

另外，可以创建ScriptableRendererFeature来实现后期处理效果。可以在管线的不同阶段注入ScriptableRenderPasses：

BeforeRendering
BeforeRenderingShadows
AfterRenderingShadows
BeforeRenderingPrepasses
AfterRenderingPrePasses
BeforeRenderingOpaques
AfterRenderingOpaques
BeforeRenderingSkybox
AfterRenderingSkybox
BeforeRenderingTransparents
AfterRenderingTransparents
BeforeRenderingPostProcessing
AfterRenderingPostProcessing
AfterRendering

下面是一个示例：

public class CustomRenderPassFeature : ScriptableRendererFeature
{class CustomRenderPass : ScriptableRenderPass{CustomRPSettings _CustomRPSettings;RenderTargetHandle _TemporaryColorTexture;private RenderTargetIdentifier _Source;private RenderTargetHandle _Destination;public CustomRenderPass(CustomRPSettings settings){_CustomRPSettings = settings;}public void Setup(RenderTargetIdentifier source, RenderTargetHandle destination){_Source = source;_Destination = destination;}public override void Configure(CommandBuffer cmd, RenderTextureDescriptor cameraTextureDescriptor){_TemporaryColorTexture.Init("_TemporaryColorTexture");}public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData){CommandBuffer cmd = CommandBufferPool.Get("My Pass");if (_Destination == RenderTargetHandle.CameraTarget){cmd.GetTemporaryRT(_TemporaryColorTexture.id, renderingData.cameraData.cameraTargetDescriptor, FilterMode.Point);cmd.Blit(_Source, _TemporaryColorTexture.Identifier());cmd.Blit(_TemporaryColorTexture.Identifier(), _Source, _CustomRPSettings.m_Material);}else{cmd.Blit(_Source, _Destination.Identifier(), _CustomRPSettings.m_Material, 0);}context.ExecuteCommandBuffer(cmd);CommandBufferPool.Release(cmd);}public override void FrameCleanup(CommandBuffer cmd){if (_Destination == RenderTargetHandle.CameraTarget){cmd.ReleaseTemporaryRT(_TemporaryColorTexture.id);}}}[System.Serializable]public class CustomRPSettings{public Material m_Material;}public CustomRPSettings m_CustomRPSettings = new CustomRPSettings();CustomRenderPass _ScriptablePass;public override void Create(){_ScriptablePass = new CustomRenderPass(m_CustomRPSettings);_ScriptablePass.renderPassEvent = RenderPassEvent.AfterRenderingOpaques;}public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData){_ScriptablePass.Setup(renderer.cameraColorTarget, RenderTargetHandle.CameraTarget);renderer.EnqueuePass(_ScriptablePass);}
}