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前言

在之前的文章中，我们学习了 ShaderLab 中 BuildIn Render Pipeline 下的Shader书写。在这篇文章中，我们来了解一下 URP 下 的最简Shader怎么编写。

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一、 我们先了解一下 Shader Graph 怎么操作

1、了解一下 Shader Graph 的面板信息

2、修改Shader路径

3、鼠标中键 或 Alt + 鼠标左键 移动画布

4、鼠标右键 打开创建节点菜单

5、把ShaderGraph节点转化为 Shader 代码

• 可以直接 查看 或 复制 编译后的Shader
  

6、可以看出 URP 和 BuildIn RP 大体框架一致

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二、把ShaderGraph转化后的 Shader 只保留最基础的通用前向渲染Pass

因为是由ShaderGraph转化过来的。所以，这里虽然简化了。但是，还是过于臃肿，在之后的文章中，我们来优化一下

Shader "MyShader/P2_10"
{Properties {}SubShader{Tags{"RenderPipeline"="UniversalPipeline""RenderType"="Opaque""Queue"="Geometry"}Pass{Name "Universal Forward"Tags{// LightMode: <None>}// Render StateCull BackBlend One ZeroZTest LEqualZWrite On// Debug// <None>// --------------------------------------------------// PassHLSLPROGRAM// Pragmas#pragma target 2.0#pragma multi_compile_instancing#pragma multi_compile_fog#pragma instancing_options renderinglayer#pragma vertex vert#pragma fragment frag// Keywords#pragma multi_compile _ LIGHTMAP_ON#pragma multi_compile _ DIRLIGHTMAP_COMBINED#pragma shader_feature _ _SAMPLE_GI#pragma multi_compile_fragment _ _DBUFFER_MRT1 _DBUFFER_MRT2 _DBUFFER_MRT3#pragma multi_compile_fragment _ DEBUG_DISPLAY#pragma multi_compile_fragment _ _SCREEN_SPACE_OCCLUSION// GraphKeywords: <None>// Defines#define ATTRIBUTES_NEED_NORMAL#define ATTRIBUTES_NEED_TANGENT#define VARYINGS_NEED_POSITION_WS#define VARYINGS_NEED_NORMAL_WS#define FEATURES_GRAPH_VERTEX/* WARNING: $splice Could not find named fragment 'PassInstancing' */#define SHADERPASS SHADERPASS_UNLIT#define _FOG_FRAGMENT 1/* WARNING: $splice Could not find named fragment 'DotsInstancingVars' */// custom interpolator pre-include/* WARNING: $splice Could not find named fragment 'sgci_CustomInterpolatorPreInclude' */// Includes#include "Packages/com.unity.render-pipelines.core/ShaderLibrary/Color.hlsl"#include "Packages/com.unity.render-pipelines.core/ShaderLibrary/Texture.hlsl"#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl"#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Input.hlsl"#include "Packages/com.unity.render-pipelines.core/ShaderLibrary/TextureStack.hlsl"#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/ShaderGraphFunctions.hlsl"#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/DBuffer.hlsl"#include "Packages/com.unity.render-pipelines.universal/Editor/ShaderGraph/Includes/ShaderPass.hlsl"// --------------------------------------------------// Structs and Packing// custom interpolators pre packing/* WARNING: $splice Could not find named fragment 'CustomInterpolatorPrePacking' */struct Attributes{float3 positionOS : POSITION;float3 normalOS : NORMAL;float4 tangentOS : TANGENT;#if UNITY_ANY_INSTANCING_ENABLEDuint instanceID : INSTANCEID_SEMANTIC;#endif};struct Varyings{float4 positionCS : SV_POSITION;float3 positionWS;float3 normalWS;#if UNITY_ANY_INSTANCING_ENABLEDuint instanceID : CUSTOM_INSTANCE_ID;#endif#if (defined(UNITY_STEREO_MULTIVIEW_ENABLED)) || (defined(UNITY_STEREO_INSTANCING_ENABLED) && (defined(SHADER_API_GLES3) || defined(SHADER_API_GLCORE)))uint stereoTargetEyeIndexAsBlendIdx0 : BLENDINDICES0;#endif#if (defined(UNITY_STEREO_INSTANCING_ENABLED))uint stereoTargetEyeIndexAsRTArrayIdx : SV_RenderTargetArrayIndex;#endif#if defined(SHADER_STAGE_FRAGMENT) && defined(VARYINGS_NEED_CULLFACE)FRONT_FACE_TYPE cullFace : FRONT_FACE_SEMANTIC;#endif};struct SurfaceDescriptionInputs{};struct VertexDescriptionInputs{float3 ObjectSpaceNormal;float3 ObjectSpaceTangent;float3 ObjectSpacePosition;};struct PackedVaryings{float4 positionCS : SV_POSITION;float3 positionWS : INTERP0;float3 normalWS : INTERP1;#if UNITY_ANY_INSTANCING_ENABLEDuint instanceID : CUSTOM_INSTANCE_ID;#endif#if (defined(UNITY_STEREO_MULTIVIEW_ENABLED)) || (defined(UNITY_STEREO_INSTANCING_ENABLED) && (defined(SHADER_API_GLES3) || defined(SHADER_API_GLCORE)))uint stereoTargetEyeIndexAsBlendIdx0 : BLENDINDICES0;#endif#if (defined(UNITY_STEREO_INSTANCING_ENABLED))uint stereoTargetEyeIndexAsRTArrayIdx : SV_RenderTargetArrayIndex;#endif#if defined(SHADER_STAGE_FRAGMENT) && defined(VARYINGS_NEED_CULLFACE)FRONT_FACE_TYPE cullFace : FRONT_FACE_SEMANTIC;#endif};PackedVaryings PackVaryings(Varyings input){PackedVaryings output;ZERO_INITIALIZE(PackedVaryings, output);output.positionCS = input.positionCS;output.positionWS.xyz = input.positionWS;output.normalWS.xyz = input.normalWS;#if UNITY_ANY_INSTANCING_ENABLEDoutput.instanceID = input.instanceID;#endif#if (defined(UNITY_STEREO_MULTIVIEW_ENABLED)) || (defined(UNITY_STEREO_INSTANCING_ENABLED) && (defined(SHADER_API_GLES3) || defined(SHADER_API_GLCORE)))output.stereoTargetEyeIndexAsBlendIdx0 = input.stereoTargetEyeIndexAsBlendIdx0;#endif#if (defined(UNITY_STEREO_INSTANCING_ENABLED))output.stereoTargetEyeIndexAsRTArrayIdx = input.stereoTargetEyeIndexAsRTArrayIdx;#endif#if defined(SHADER_STAGE_FRAGMENT) && defined(VARYINGS_NEED_CULLFACE)output.cullFace = input.cullFace;#endifreturn output;}Varyings UnpackVaryings(PackedVaryings input){Varyings output;output.positionCS = input.positionCS;output.positionWS = input.positionWS.xyz;output.normalWS = input.normalWS.xyz;#if UNITY_ANY_INSTANCING_ENABLEDoutput.instanceID = input.instanceID;#endif#if (defined(UNITY_STEREO_MULTIVIEW_ENABLED)) || (defined(UNITY_STEREO_INSTANCING_ENABLED) && (defined(SHADER_API_GLES3) || defined(SHADER_API_GLCORE)))output.stereoTargetEyeIndexAsBlendIdx0 = input.stereoTargetEyeIndexAsBlendIdx0;#endif#if (defined(UNITY_STEREO_INSTANCING_ENABLED))output.stereoTargetEyeIndexAsRTArrayIdx = input.stereoTargetEyeIndexAsRTArrayIdx;#endif#if defined(SHADER_STAGE_FRAGMENT) && defined(VARYINGS_NEED_CULLFACE)output.cullFace = input.cullFace;#endifreturn output;}// --------------------------------------------------// Graph// Graph PropertiesCBUFFER_START(UnityPerMaterial)CBUFFER_END// Object and Global properties// Graph Includes// GraphIncludes: <None>// -- Property used by ScenePickingPass#ifdef SCENEPICKINGPASSfloat4 _SelectionID;#endif// -- Properties used by SceneSelectionPass#ifdef SCENESELECTIONPASSint _ObjectId;int _PassValue;#endif// Graph Functions// GraphFunctions: <None>// Custom interpolators pre vertex/* WARNING: $splice Could not find named fragment 'CustomInterpolatorPreVertex' */// Graph Vertexstruct VertexDescription{float3 Position;float3 Normal;float3 Tangent;};VertexDescription VertexDescriptionFunction(VertexDescriptionInputs IN){VertexDescription description = (VertexDescription)0;description.Position = IN.ObjectSpacePosition;description.Normal = IN.ObjectSpaceNormal;description.Tangent = IN.ObjectSpaceTangent;return description;}// Custom interpolators, pre surface#ifdef FEATURES_GRAPH_VERTEXVaryings CustomInterpolatorPassThroughFunc(inout Varyings output, VertexDescription input){return output;}#define CUSTOMINTERPOLATOR_VARYPASSTHROUGH_FUNC#endif// Graph Pixelstruct SurfaceDescription{float3 BaseColor;};SurfaceDescription SurfaceDescriptionFunction(SurfaceDescriptionInputs IN){SurfaceDescription surface = (SurfaceDescription)0;surface.BaseColor = IsGammaSpace() ? float3(0.5, 0.5, 0.5) : SRGBToLinear(float3(0.5, 0.5, 0.5));return surface;}// --------------------------------------------------// Build Graph Inputs#ifdef HAVE_VFX_MODIFICATION#define VFX_SRP_ATTRIBUTES Attributes#define VFX_SRP_VARYINGS Varyings#define VFX_SRP_SURFACE_INPUTS SurfaceDescriptionInputs#endifVertexDescriptionInputs BuildVertexDescriptionInputs(Attributes input){VertexDescriptionInputs output;ZERO_INITIALIZE(VertexDescriptionInputs, output);output.ObjectSpaceNormal = input.normalOS;output.ObjectSpaceTangent = input.tangentOS.xyz;output.ObjectSpacePosition = input.positionOS;return output;}SurfaceDescriptionInputs BuildSurfaceDescriptionInputs(Varyings input){SurfaceDescriptionInputs output;ZERO_INITIALIZE(SurfaceDescriptionInputs, output);#ifdef HAVE_VFX_MODIFICATION#if VFX_USE_GRAPH_VALUESuint instanceActiveIndex = asuint(UNITY_ACCESS_INSTANCED_PROP(PerInstance, _InstanceActiveIndex));/* WARNING: $splice Could not find named fragment 'VFXLoadGraphValues' */#endif/* WARNING: $splice Could not find named fragment 'VFXSetFragInputs' */#endif#if UNITY_UV_STARTS_AT_TOP#else#endif#if defined(SHADER_STAGE_FRAGMENT) && defined(VARYINGS_NEED_CULLFACE)#define BUILD_SURFACE_DESCRIPTION_INPUTS_OUTPUT_FACESIGN output.FaceSign =                    IS_FRONT_VFACE(input.cullFace, true, false);#else#define BUILD_SURFACE_DESCRIPTION_INPUTS_OUTPUT_FACESIGN#endif#undef BUILD_SURFACE_DESCRIPTION_INPUTS_OUTPUT_FACESIGNreturn output;}// --------------------------------------------------// Main#include "Packages/com.unity.render-pipelines.universal/Editor/ShaderGraph/Includes/Varyings.hlsl"#include "Packages/com.unity.render-pipelines.universal/Editor/ShaderGraph/Includes/UnlitPass.hlsl"// --------------------------------------------------// Visual Effect Vertex Invocations#ifdef HAVE_VFX_MODIFICATION#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/VisualEffectVertex.hlsl"#endifENDHLSL}}FallBack "Hidden/Shader Graph/FallbackError"
}

1、我们看一下 URP Pass不可用后使用的默认Shader

使用的是内置渲染管线，返回颜色为洋葱紫

Shader "Hidden/Universal Render Pipeline/FallbackError"
{SubShader{Tags{"RenderType" = "Opaque""RenderPipeline" = "UniversalPipeline""IgnoreProjector" = "True"}Pass{HLSLPROGRAM#pragma target 2.0#pragma editor_sync_compilation// -------------------------------------// Shader Stages#pragma vertex vert#pragma fragment frag// -------------------------------------// Unity defined keywords#pragma multi_compile _ STEREO_INSTANCING_ON STEREO_MULTIVIEW_ON//--------------------------------------// GPU Instancing#include_with_pragmas "Packages/com.unity.render-pipelines.universal/ShaderLibrary/DOTS.hlsl"// -------------------------------------// Includes#include "Packages/com.unity.render-pipelines.core/ShaderLibrary/Common.hlsl"#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Input.hlsl"struct appdata_t{float4 vertex : POSITION;UNITY_VERTEX_INPUT_INSTANCE_ID};struct v2f{float4 vertex : SV_POSITION;UNITY_VERTEX_OUTPUT_STEREO};v2f vert (appdata_t v){v2f o;UNITY_SETUP_INSTANCE_ID(v);UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);o.vertex = TransformObjectToHClip(v.vertex.xyz);return o;}float4 frag (v2f i) : SV_Target{return float4(1,0,1,1);}ENDHLSL}}Fallback "Hidden/Core/FallbackError"
}