本篇文章轉(zhuǎn)自Teofilo Dutra編寫的《From Built-in to URP》，其中有很多在寫URP管線Shader時(shí)需要用到的函數(shù)，作為備忘速查表非常實(shí)用，所以記錄于此。本文經(jīng)過(guò)精簡(jiǎn)和翻譯，不一定適用于大家，可以點(diǎn)擊上方鏈接跳轉(zhuǎn)至作者原文。本文是基于7.3版本的URP編寫的，有些暫時(shí)還不支持的內(nèi)容可能在后續(xù)版本更新迭代。

結(jié)構(gòu)

首先要在SubShader的Tags中添加”RenderPipeline” = “UniversalPipeline”，并且使用HLSL的宏代替舊版的CG語(yǔ)言宏。

Built-inURP

CGPROGRAM / HLSLPROGRAM	HLSLPROGRAM
ENDCG / ENDHLSL	ENDHLSL
CGINCLUDE / HLSLINCLUDE	HLSLINCLUDE

Include文件的改動(dòng)

ContentBuilt-inURP

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	無(wú)

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-inURP

ForwardBase	UniversalForward
ForwardAdd	無(wú)
Deferred and related	UniversalGBuffer seems to have just been added to URP
Vertex and related	無(wú)
ShadowCaster	ShadowCaster
MotionVectors	暫不支持

URP其他支持的光照模式：

• DepthOnly
• Meta (用于烘焙光照貼圖)
• Universal2D

變體(Variants)

URP支持著色器的變體，可以使用#pragma multi_compile宏實(shí)現(xiàn)編譯不同需求下的著色器，常見的內(nèi)置關(guān)鍵字有：

• _MAIN_LIGHT_SHADOWS
• _MAIN_LIGHT_SHADOWS_CASCADE
• _ADDITIONAL_LIGHTS_VERTEX
• _ADDITIONAL_LIGHTS
• _ADDITIONAL_LIGHT_SHADOWS
• _SHADOWS_SOFT
• _MIXED_LIGHTING_SUBTRACTIVE

預(yù)定義的著色器預(yù)處理宏

輔助宏(Helpers)

Built-inURP

UNITY_PROJ_COORD(a)	無(wú)，使用 a.xy/a.w 來(lái)代替
UNITY_INITIALIZE_OUTPUT(type, name)	ZERO_INITIALIZE(type, name)

陰影貼圖

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

Built-inURP

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)

紋理/采樣器的聲明宏

Built-inURP

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)

內(nèi)置的著色器輔助函數(shù)

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

頂點(diǎn)變換函數(shù)

Built-inURP

float4 UnityObjectToClipPos(float3 pos)	float4 TransformObjectToHClip(float3 positionOS)
float3 UnityObjectToViewPos(float3 pos)	TransformWorldToView(TransformObjectToWorld(positionOS))

泛用的輔助函數(shù)

Built-inURPInclude

float3 WorldSpaceViewDir (float4 v)	float3 GetWorldSpaceViewDir(float3 positionWS)	Include “Packages/com.unity.render-pipelines.universal/ShaderLibrary/ShaderVariablesFunctions.hlsl”
float3 ObjSpaceViewDir (float4 v)	無(wú)，使用 TransformWorldToObject(GetCameraPositionWS()) - objectSpacePosition;
float2 ParallaxOffset (half h, half height, half3 viewDir)	可能沒有，從 UnityCG.cginc 復(fù)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 為 half4(LIGHTMAP_HDR_MULTIPLIER, LIGHTMAP_HDR_EXPONENT, 0.0h, 0.0h)
float4 EncodeFloatRGBA (float v)	可能沒有， 從 UnityCG.cginc 復(fù)制
float DecodeFloatRGBA (float4 enc)	可能沒有， 從 UnityCG.cginc 復(fù)制
float2 EncodeFloatRG (float v)	可能沒有， 從 UnityCG.cginc 復(fù)制
float DecodeFloatRG (float2 enc)	可能沒有， 從 UnityCG.cginc 復(fù)制
float2 EncodeViewNormalStereo (float3 n)	可能沒有， 從 UnityCG.cginc 復(fù)制
float3 DecodeViewNormalStereo (float4 enc4)	可能沒有， 從 UnityCG.cginc 復(fù)制

前向渲染輔助函數(shù)

Built-inURPInclude

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 (…)	無(wú)，可嘗試用half3 VertexLighting(float3 positionWS, half3 normalWS)	include “Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl”

屏幕空間輔助函數(shù)

Built-inURPInclude

float4 ComputeScreenPos (float4 clipPos)	float4 ComputeScreenPos(float4 positionCS)	Include “Packages/com.unity.render-pipelines.universal/ShaderLibrary/ShaderVariablesFunctions.hlsl”
float4 ComputeGrabScreenPos (float4 clipPos)	無(wú)

頂點(diǎn)光照的輔助函數(shù)

Built-inURPInclude

float3 ShadeVertexLights (float4 vertex, float3 normal)	無(wú)，可嘗試用 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 中找到一些通用函數(shù)

內(nèi)置的著色器變量

Built-inURPInclude

_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	可能還不支持
unity_4LightPosX0, unity_4LightPosY0, unity_4LightPosZ0	URP中，額外的燈光存儲(chǔ)在一個(gè)數(shù)組或緩沖中(取決于平臺(tái)),使用Light GetAdditionalLight(uint i, float3 positionWS)獲取光照信息	Include “Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl”
unity_4LightAtten0	URP中，額外的燈光存儲(chǔ)在一個(gè)數(shù)組或緩沖中(取決于平臺(tái)),使用Light GetAdditionalLight(uint i, float3 positionWS)獲取光照信息	Include “Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl”
unity_LightColor	URP中，額外的燈光存儲(chǔ)在一個(gè)數(shù)組或緩沖中(取決于平臺(tái)),使用Light GetAdditionalLight(uint i, float3 positionWS)獲取光照信息	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(…)獲取額外的光源，也可以使用GetAdditionalLightsCount()查詢額外的光源數(shù)量。

其他方法

陰影

更多陰影相關(guān)函數(shù)可以查看 Packages/com.unity.render-pipelines.universal/ShaderLibrary/Shadows.hlsl

Built-inURP

UNITY_SHADOW_COORDS(x)	可能沒有，可以寫作float4 shadowCoord : TEXCOORD0;
TRANSFER_SHADOW(a)	a.shadowCoord = TransformWorldToShadowCoord(worldSpacePosition)
SHADOWS_SCREEN	暫不支持

霧

更多霧相關(guān)的函數(shù)可以查看 Packages/com.unity.render-pipelines.universal/ShaderLibrary/ShaderVariablesFunctions.hlsl

Built-inURP

UNITY_FOG_COORDS(x)	可能沒有，可以寫作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來(lái)調(diào)用深度紋理。也可以使用SampleSceneDepth(…) 和 LoadSceneDepth(…)。

Built-inURPInclude

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-inURPInclude

ShadeSH9(normal)	SampleSH(normal)	Include “Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl”
unity_ColorSpaceLuminance	無(wú)，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提供了渲染管線中注入的位置：

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

例如：

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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，可以創(chuàng)建ScriptableRendererFeature來(lái)實(shí)現(xiàn)后期處理效果。可以在管線的不同階段注入ScriptableRenderPasses：

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

下面是一個(gè)示例：

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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);} }

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