【URP】Unity3D物体遮罩的多种方案实现

【从UnityURP开始探索游戏渲染】专栏-直达

基于Unity URP实现3D物体方向性动态遮罩

‌Shader核心功能‌：

• 通过_MaskDirection向量定义遮罩方向
• 使用_MaskProgress参数(0-1范围)控制显示比例
• 基于顶点世界坐标在遮罩方向上的投影值进行裁剪(clip)
• 兼容URP渲染管线标准结构

‌控制器特点‌：

• 支持运行时动态调整遮罩方向和进度

• 内置演示动画(旋转方向和进度波动)

• 提供外部调用接口用于程序控制

• 自动规范化方向向量确保计算准确

• DirectionalMask.shader

  Shader "Custom/DirectionalMask"
  {
      Properties
      {
          _MainTex("Texture", 2D) = "white" {}
          _MaskDirection("Mask Direction", Vector) = (1,0,0,0)
          _MaskProgress("Mask Progress", Range(0, 1)) = 0.5
      }
  
      SubShader
      {
          Tags { "RenderType"="Opaque" "RenderPipeline"="UniversalPipeline" }
  
          HLSLINCLUDE
          #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
  
          struct Attributes
          {
              float4 positionOS : POSITION;
              float2 uv : TEXCOORD0;
          };
  
          struct Varyings
          {
              float4 positionCS : SV_POSITION;
              float2 uv : TEXCOORD0;
              float3 positionWS : TEXCOORD1;
          };
  
          TEXTURE2D(_MainTex);
          SAMPLER(sampler_MainTex);
          float4 _MainTex_ST;
          float3 _MaskDirection;
          float _MaskProgress;
  
          Varyings Vert(Attributes input)
          {
              Varyings output;
              output.positionCS = TransformObjectToHClip(input.positionOS.xyz);
              output.uv = TRANSFORM_TEX(input.uv, _MainTex);
              output.positionWS = TransformObjectToWorld(input.positionOS.xyz);
              return output;
          }
  
          half4 Frag(Varyings input) : SV_Target
          {
              half4 col = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, input.uv);
              
              // 计算物体顶点在遮罩方向上的投影比例
              float dotProduct = dot(normalize(input.positionWS), normalize(_MaskDirection));
              float normalizedDot = (dotProduct + 1) * 0.5; // 映射到0-1范围
              
              // 根据进度参数裁剪
              clip(normalizedDot - _MaskProgress);
              
              return col;
          }
          ENDHLSL
  
          Pass
          {
              HLSLPROGRAM
              #pragma vertex Vert
              #pragma fragment Frag
              ENDHLSL
          }
      }
  }
  
  

• DirectionalMaskController.cs

  using UnityEngine;
  
  public class DirectionalMaskController : MonoBehaviour
  {
      [SerializeField] private Renderer _targetRenderer;
      [SerializeField] private Vector3 _maskDirection = Vector3.right;
      [Range(0, 1)] public float maskProgress = 0.5f;
      [SerializeField] private float _rotationSpeed = 30f;
      [SerializeField] private float _progressSpeed = 0.2f;
  
      private Material _material;
      private static readonly int MaskDirection = Shader.PropertyToID("_MaskDirection");
      private static readonly int MaskProgress = Shader.PropertyToID("_MaskProgress");
  
      void Start()
      {
          _material = _targetRenderer.material;
          UpdateShaderParams();
      }
  
      void Update()
      {
          // 动态旋转遮罩方向
          _maskDirection = Quaternion.Euler(0, _rotationSpeed * Time.deltaTime, 0) * _maskDirection;
          
          // 动态调整遮罩进度
          maskProgress = Mathf.PingPong(Time.time * _progressSpeed, 1f);
          
          UpdateShaderParams();
      }
  
      private void UpdateShaderParams()
      {
          _material.SetVector(MaskDirection, _maskDirection.normalized);
          _material.SetFloat(MaskProgress, maskProgress);
      }
  
      // 外部调用接口
      public void SetMaskDirection(Vector3 newDirection)
      {
          _maskDirection = newDirection.normalized;
          UpdateShaderParams();
      }
  
      public void SetMaskProgress(float progress)
      {
          maskProgress = Mathf.Clamp01(progress);
          UpdateShaderParams();
      }
  }
  

‌扩展：

• 可添加_MaskSharpness参数控制边缘过渡柔和度
• 结合Stencil Buffer实现多物体遮罩叠加
• 通过AnimationCurve控制进度变化曲线

该方案相比基础遮罩实现增加了方向向量参数和动态进度控制，通过顶点投影计算实现方向性裁剪效果。控制器脚本支持运行时动态调整所有参数，并保持与Shader的高效数据交互。

‌HLSL Shader实现‌（基于透明度遮罩）：

• unity_urp遮罩shader

  Shader "Custom/TransparentColorURP" {
      Properties {
          _Color("Color Tint", Color) = (1,1,1,1)
          _MainTex("Main Tex", 2D) = "white" {}
          _AlphaScale("Alpha Scale", Range(0, 1)) = 0.5
      }
      SubShader {
          Pass {
              ZWrite On
              ColorMask 0
          }
          Pass {
              ZWrite Off
              Blend SrcAlpha OneMinusSrcAlpha
              // HLSL代码...
          }
      }
  }
  

‌控制脚本‌：

• unity_遮罩控制脚本

  public class MaskController : MonoBehaviour {
      public Renderer targetRenderer;
      public float maskProgress = 0.5f;
  
      void Update() {
          targetRenderer.material.SetFloat("_AlphaScale", 
              Mathf.PingPong(Time.time, 1f));
      }
  }
  

‌模板Shader核心代码‌：

• 创建一个四边形，将StencilMask做成材质赋给它。通过调整四边形的大小，来调整遮罩区域。

• 当然也可在c#端动态调整mesh的点来做动态异形遮罩。

• 将需要被遮罩的URP中Lit的物体，换成StencilLit的shader。这样原来的Lit的物体就支持StencilMask的遮罩了。

• StencilMask.shader

  Shader "Custom/StencilMask"
  {
      SubShader
      {
          Tags { "RenderType"="Opaque" "Queue"="Geometry-100" }
          
          Pass
          {
              ColorMask 0
              ZWrite Off
              
              Stencil {
                  Ref 1
                  Comp Always
                  Pass Replace
              }
          }
      }
  }
  

• StencilLit.shader

  Shader "Universal Render Pipeline/StencilLit"
  {
      Properties
      {
          // Specular vs Metallic workflow
          _WorkflowMode("WorkflowMode", Float) = 1.0
  
          [MainTexture] _BaseMap("Albedo", 2D) = "white" {}
          [MainColor] _BaseColor("Color", Color) = (1,1,1,1)
  
          _Cutoff("Alpha Cutoff", Range(0.0, 1.0)) = 0.5
  
          _Smoothness("Smoothness", Range(0.0, 1.0)) = 0.5
          _SmoothnessTextureChannel("Smoothness texture channel", Float) = 0
  
          _Metallic("Metallic", Range(0.0, 1.0)) = 0.0
          _MetallicGlossMap("Metallic", 2D) = "white" {}
  
          _SpecColor("Specular", Color) = (0.2, 0.2, 0.2)
          _SpecGlossMap("Specular", 2D) = "white" {}
  
          [ToggleOff] _SpecularHighlights("Specular Highlights", Float) = 1.0
          [ToggleOff] _EnvironmentReflections("Environment Reflections", Float) = 1.0
  
          _BumpScale("Scale", Float) = 1.0
          _BumpMap("Normal Map", 2D) = "bump" {}
  
          _Parallax("Scale", Range(0.005, 0.08)) = 0.005
          _ParallaxMap("Height Map", 2D) = "black" {}
  
          _OcclusionStrength("Strength", Range(0.0, 1.0)) = 1.0
          _OcclusionMap("Occlusion", 2D) = "white" {}
  
          [HDR] _EmissionColor("Color", Color) = (0,0,0)
          _EmissionMap("Emission", 2D) = "white" {}
  
          _DetailMask("Detail Mask", 2D) = "white" {}
          _DetailAlbedoMapScale("Scale", Range(0.0, 2.0)) = 1.0
          _DetailAlbedoMap("Detail Albedo x2", 2D) = "linearGrey" {}
          _DetailNormalMapScale("Scale", Range(0.0, 2.0)) = 1.0
          [Normal] _DetailNormalMap("Normal Map", 2D) = "bump" {}
  
          // SRP batching compatibility for Clear Coat (Not used in Lit)
          [HideInInspector] _ClearCoatMask("_ClearCoatMask", Float) = 0.0
          [HideInInspector] _ClearCoatSmoothness("_ClearCoatSmoothness", Float) = 0.0
  
          // Blending state
          _Surface("__surface", Float) = 0.0
          _Blend("__blend", Float) = 0.0
          _Cull("__cull", Float) = 2.0
          [ToggleUI] _AlphaClip("__clip", Float) = 0.0
          [HideInInspector] _SrcBlend("__src", Float) = 1.0
          [HideInInspector] _DstBlend("__dst", Float) = 0.0
          [HideInInspector] _SrcBlendAlpha("__srcA", Float) = 1.0
          [HideInInspector] _DstBlendAlpha("__dstA", Float) = 0.0
          [HideInInspector] _ZWrite("__zw", Float) = 1.0
          [HideInInspector] _BlendModePreserveSpecular("_BlendModePreserveSpecular", Float) = 1.0
          [HideInInspector] _AlphaToMask("__alphaToMask", Float) = 0.0
  
          [ToggleUI] _ReceiveShadows("Receive Shadows", Float) = 1.0
          // Editmode props
          _QueueOffset("Queue offset", Float) = 0.0
  
          // ObsoleteProperties
          [HideInInspector] _MainTex("BaseMap", 2D) = "white" {}
          [HideInInspector] _Color("Base Color", Color) = (1, 1, 1, 1)
          [HideInInspector] _GlossMapScale("Smoothness", Float) = 0.0
          [HideInInspector] _Glossiness("Smoothness", Float) = 0.0
          [HideInInspector] _GlossyReflections("EnvironmentReflections", Float) = 0.0
  
          [HideInInspector][NoScaleOffset]unity_Lightmaps("unity_Lightmaps", 2DArray) = "" {}
          [HideInInspector][NoScaleOffset]unity_LightmapsInd("unity_LightmapsInd", 2DArray) = "" {}
          [HideInInspector][NoScaleOffset]unity_ShadowMasks("unity_ShadowMasks", 2DArray) = "" {}
      }
  
      SubShader
      {
          // Universal Pipeline tag is required. If Universal render pipeline is not set in the graphics settings
          // this Subshader will fail. One can add a subshader below or fallback to Standard built-in to make this
          // material work with both Universal Render Pipeline and Builtin Unity Pipeline
          Tags
          {
              "RenderType" = "Opaque"
              "RenderPipeline" = "UniversalPipeline"
              "UniversalMaterialType" = "Lit"
              "IgnoreProjector" = "True"
          }
          LOD 300
  
          // ------------------------------------------------------------------
          //  Forward pass. Shades all light in a single pass. GI + emission + Fog
          Pass
          {
              // Lightmode matches the ShaderPassName set in UniversalRenderPipeline.cs. SRPDefaultUnlit and passes with
              // no LightMode tag are also rendered by Universal Render Pipeline
              Name "ForwardLit"
              Tags
              {
                  "LightMode" = "UniversalForward"
              }
  
              // -------------------------------------
              // Render State Commands
              Blend[_SrcBlend][_DstBlend], [_SrcBlendAlpha][_DstBlendAlpha]
              ZWrite[_ZWrite]
              Cull[_Cull]
              AlphaToMask[_AlphaToMask]
              Stencil {
                  Ref 1
                  Comp Equal
                  Pass Keep
              }
  
              HLSLPROGRAM
              #pragma target 2.0
  
              // -------------------------------------
              // Shader Stages
              #pragma vertex LitPassVertex
              #pragma fragment LitPassFragment
  
              // -------------------------------------
              // Material Keywords
              #pragma shader_feature_local _NORMALMAP
              #pragma shader_feature_local _PARALLAXMAP
              #pragma shader_feature_local _RECEIVE_SHADOWS_OFF
              #pragma shader_feature_local _ _DETAIL_MULX2 _DETAIL_SCALED
              #pragma shader_feature_local_fragment _SURFACE_TYPE_TRANSPARENT
              #pragma shader_feature_local_fragment _ALPHATEST_ON
              #pragma shader_feature_local_fragment _ _ALPHAPREMULTIPLY_ON _ALPHAMODULATE_ON
              #pragma shader_feature_local_fragment _EMISSION
              #pragma shader_feature_local_fragment _METALLICSPECGLOSSMAP
              #pragma shader_feature_local_fragment _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
              #pragma shader_feature_local_fragment _OCCLUSIONMAP
              #pragma shader_feature_local_fragment _SPECULARHIGHLIGHTS_OFF
              #pragma shader_feature_local_fragment _ENVIRONMENTREFLECTIONS_OFF
              #pragma shader_feature_local_fragment _SPECULAR_SETUP
  
              // -------------------------------------
              // Universal Pipeline keywords
              #pragma multi_compile _ _MAIN_LIGHT_SHADOWS _MAIN_LIGHT_SHADOWS_CASCADE _MAIN_LIGHT_SHADOWS_SCREEN
              #pragma multi_compile _ _ADDITIONAL_LIGHTS_VERTEX _ADDITIONAL_LIGHTS
              #pragma multi_compile _ EVALUATE_SH_MIXED EVALUATE_SH_VERTEX
              #pragma multi_compile_fragment _ _ADDITIONAL_LIGHT_SHADOWS
              #pragma multi_compile_fragment _ _REFLECTION_PROBE_BLENDING
              #pragma multi_compile_fragment _ _REFLECTION_PROBE_BOX_PROJECTION
              #pragma multi_compile_fragment _ _SHADOWS_SOFT _SHADOWS_SOFT_LOW _SHADOWS_SOFT_MEDIUM _SHADOWS_SOFT_HIGH
              #pragma multi_compile_fragment _ _SCREEN_SPACE_OCCLUSION
              #pragma multi_compile_fragment _ _DBUFFER_MRT1 _DBUFFER_MRT2 _DBUFFER_MRT3
              #pragma multi_compile_fragment _ _LIGHT_COOKIES
              #pragma multi_compile _ _LIGHT_LAYERS
              #pragma multi_compile _ _FORWARD_PLUS
              #include_with_pragmas "Packages/com.unity.render-pipelines.universal/ShaderLibrary/RenderingLayers.hlsl"
  
              // -------------------------------------
              // Unity defined keywords
              #pragma multi_compile _ LIGHTMAP_SHADOW_MIXING
              #pragma multi_compile _ SHADOWS_SHADOWMASK
              #pragma multi_compile _ DIRLIGHTMAP_COMBINED
              #pragma multi_compile _ LIGHTMAP_ON
              #pragma multi_compile _ DYNAMICLIGHTMAP_ON
              #pragma multi_compile_fragment _ LOD_FADE_CROSSFADE
              #pragma multi_compile_fog
              #pragma multi_compile_fragment _ DEBUG_DISPLAY
  
              //--------------------------------------
              // GPU Instancing
              #pragma multi_compile_instancing
              #pragma instancing_options renderinglayer
              #include_with_pragmas "Packages/com.unity.render-pipelines.universal/ShaderLibrary/DOTS.hlsl"
  
              #include "Packages/com.unity.render-pipelines.universal/Shaders/LitInput.hlsl"
              #include "Packages/com.unity.render-pipelines.universal/Shaders/LitForwardPass.hlsl"
              ENDHLSL
          }
  
          Pass
          {
              Name "ShadowCaster"
              Tags
              {
                  "LightMode" = "ShadowCaster"
              }
  
              // -------------------------------------
              // Render State Commands
              ZWrite On
              ZTest LEqual
              ColorMask 0
              Cull[_Cull]
  
              HLSLPROGRAM
              #pragma target 2.0
  
              // -------------------------------------
              // Shader Stages
              #pragma vertex ShadowPassVertex
              #pragma fragment ShadowPassFragment
  
              // -------------------------------------
              // Material Keywords
              #pragma shader_feature_local_fragment _ALPHATEST_ON
              #pragma shader_feature_local_fragment _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
  
              //--------------------------------------
              // GPU Instancing
              #pragma multi_compile_instancing
              #include_with_pragmas "Packages/com.unity.render-pipelines.universal/ShaderLibrary/DOTS.hlsl"
  
              // -------------------------------------
              // Universal Pipeline keywords
  
              // -------------------------------------
              // Unity defined keywords
              #pragma multi_compile_fragment _ LOD_FADE_CROSSFADE
  
              // This is used during shadow map generation to differentiate between directional and punctual light shadows, as they use different formulas to apply Normal Bias
              #pragma multi_compile_vertex _ _CASTING_PUNCTUAL_LIGHT_SHADOW
  
              // -------------------------------------
              // Includes
              #include "Packages/com.unity.render-pipelines.universal/Shaders/LitInput.hlsl"
              #include "Packages/com.unity.render-pipelines.universal/Shaders/ShadowCasterPass.hlsl"
              ENDHLSL
          }
  
          Pass
          {
              // Lightmode matches the ShaderPassName set in UniversalRenderPipeline.cs. SRPDefaultUnlit and passes with
              // no LightMode tag are also rendered by Universal Render Pipeline
              Name "GBuffer"
              Tags
              {
                  "LightMode" = "UniversalGBuffer"
              }
  
              // -------------------------------------
              // Render State Commands
              ZWrite[_ZWrite]
              ZTest LEqual
              Cull[_Cull]
  
              HLSLPROGRAM
              #pragma target 4.5
  
              // Deferred Rendering Path does not support the OpenGL-based graphics API:
              // Desktop OpenGL, OpenGL ES 3.0, WebGL 2.0.
              #pragma exclude_renderers gles3 glcore
  
              // -------------------------------------
              // Shader Stages
              #pragma vertex LitGBufferPassVertex
              #pragma fragment LitGBufferPassFragment
  
              // -------------------------------------
              // Material Keywords
              #pragma shader_feature_local _NORMALMAP
              #pragma shader_feature_local_fragment _ALPHATEST_ON
              //#pragma shader_feature_local_fragment _ALPHAPREMULTIPLY_ON
              #pragma shader_feature_local_fragment _EMISSION
              #pragma shader_feature_local_fragment _METALLICSPECGLOSSMAP
              #pragma shader_feature_local_fragment _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
              #pragma shader_feature_local_fragment _OCCLUSIONMAP
              #pragma shader_feature_local _PARALLAXMAP
              #pragma shader_feature_local _ _DETAIL_MULX2 _DETAIL_SCALED
  
              #pragma shader_feature_local_fragment _SPECULARHIGHLIGHTS_OFF
              #pragma shader_feature_local_fragment _ENVIRONMENTREFLECTIONS_OFF
              #pragma shader_feature_local_fragment _SPECULAR_SETUP
              #pragma shader_feature_local _RECEIVE_SHADOWS_OFF
  
              // -------------------------------------
              // Universal Pipeline keywords
              #pragma multi_compile _ _MAIN_LIGHT_SHADOWS _MAIN_LIGHT_SHADOWS_CASCADE _MAIN_LIGHT_SHADOWS_SCREEN
              //#pragma multi_compile _ _ADDITIONAL_LIGHTS_VERTEX _ADDITIONAL_LIGHTS
              //#pragma multi_compile _ _ADDITIONAL_LIGHT_SHADOWS
              #pragma multi_compile_fragment _ _REFLECTION_PROBE_BLENDING
              #pragma multi_compile_fragment _ _REFLECTION_PROBE_BOX_PROJECTION
              #pragma multi_compile_fragment _ _SHADOWS_SOFT _SHADOWS_SOFT_LOW _SHADOWS_SOFT_MEDIUM _SHADOWS_SOFT_HIGH
              #pragma multi_compile_fragment _ _DBUFFER_MRT1 _DBUFFER_MRT2 _DBUFFER_MRT3
              #pragma multi_compile_fragment _ _RENDER_PASS_ENABLED
              #include_with_pragmas "Packages/com.unity.render-pipelines.universal/ShaderLibrary/RenderingLayers.hlsl"
  
              // -------------------------------------
              // Unity defined keywords
              #pragma multi_compile _ LIGHTMAP_SHADOW_MIXING
              #pragma multi_compile _ SHADOWS_SHADOWMASK
              #pragma multi_compile _ DIRLIGHTMAP_COMBINED
              #pragma multi_compile _ LIGHTMAP_ON
              #pragma multi_compile _ DYNAMICLIGHTMAP_ON
              #pragma multi_compile_fragment _ LOD_FADE_CROSSFADE
              #pragma multi_compile_fragment _ _GBUFFER_NORMALS_OCT
  
              //--------------------------------------
              // GPU Instancing
              #pragma multi_compile_instancing
              #pragma instancing_options renderinglayer
              #include_with_pragmas "Packages/com.unity.render-pipelines.universal/ShaderLibrary/DOTS.hlsl"
  
              // -------------------------------------
              // Includes
              #include "Packages/com.unity.render-pipelines.universal/Shaders/LitInput.hlsl"
              #include "Packages/com.unity.render-pipelines.universal/Shaders/LitGBufferPass.hlsl"
              ENDHLSL
          }
  
          Pass
          {
              Name "DepthOnly"
              Tags
              {
                  "LightMode" = "DepthOnly"
              }
  
              // -------------------------------------
              // Render State Commands
              ZWrite On
              ColorMask R
              Cull[_Cull]
  
              HLSLPROGRAM
              #pragma target 2.0
  
              // -------------------------------------
              // Shader Stages
              #pragma vertex DepthOnlyVertex
              #pragma fragment DepthOnlyFragment
  
              // -------------------------------------
              // Material Keywords
              #pragma shader_feature_local_fragment _ALPHATEST_ON
              #pragma shader_feature_local_fragment _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
  
              // -------------------------------------
              // Unity defined keywords
              #pragma multi_compile_fragment _ LOD_FADE_CROSSFADE
  
              //--------------------------------------
              // GPU Instancing
              #pragma multi_compile_instancing
              #include_with_pragmas "Packages/com.unity.render-pipelines.universal/ShaderLibrary/DOTS.hlsl"
  
              // -------------------------------------
              // Includes
              #include "Packages/com.unity.render-pipelines.universal/Shaders/LitInput.hlsl"
              #include "Packages/com.unity.render-pipelines.universal/Shaders/DepthOnlyPass.hlsl"
              ENDHLSL
          }
  
          // This pass is used when drawing to a _CameraNormalsTexture texture
          Pass
          {
              Name "DepthNormals"
              Tags
              {
                  "LightMode" = "DepthNormals"
              }
  
              // -------------------------------------
              // Render State Commands
              ZWrite On
              Cull[_Cull]
  
              HLSLPROGRAM
              #pragma target 2.0
  
              // -------------------------------------
              // Shader Stages
              #pragma vertex DepthNormalsVertex
              #pragma fragment DepthNormalsFragment
  
              // -------------------------------------
              // Material Keywords
              #pragma shader_feature_local _NORMALMAP
              #pragma shader_feature_local _PARALLAXMAP
              #pragma shader_feature_local _ _DETAIL_MULX2 _DETAIL_SCALED
              #pragma shader_feature_local_fragment _ALPHATEST_ON
              #pragma shader_feature_local_fragment _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
  
              // -------------------------------------
              // Unity defined keywords
              #pragma multi_compile_fragment _ LOD_FADE_CROSSFADE
  
              // -------------------------------------
              // Universal Pipeline keywords
              #include_with_pragmas "Packages/com.unity.render-pipelines.universal/ShaderLibrary/RenderingLayers.hlsl"
  
              //--------------------------------------
              // GPU Instancing
              #pragma multi_compile_instancing
              #include_with_pragmas "Packages/com.unity.render-pipelines.universal/ShaderLibrary/DOTS.hlsl"
  
              // -------------------------------------
              // Includes
              #include "Packages/com.unity.render-pipelines.universal/Shaders/LitInput.hlsl"
              #include "Packages/com.unity.render-pipelines.universal/Shaders/LitDepthNormalsPass.hlsl"
              ENDHLSL
          }
  
          // This pass it not used during regular rendering, only for lightmap baking.
          Pass
          {
              Name "Meta"
              Tags
              {
                  "LightMode" = "Meta"
              }
  
              // -------------------------------------
              // Render State Commands
              Cull Off
  
              HLSLPROGRAM
              #pragma target 2.0
  
              // -------------------------------------
              // Shader Stages
              #pragma vertex UniversalVertexMeta
              #pragma fragment UniversalFragmentMetaLit
  
              // -------------------------------------
              // Material Keywords
              #pragma shader_feature_local_fragment _SPECULAR_SETUP
              #pragma shader_feature_local_fragment _EMISSION
              #pragma shader_feature_local_fragment _METALLICSPECGLOSSMAP
              #pragma shader_feature_local_fragment _ALPHATEST_ON
              #pragma shader_feature_local_fragment _ _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
              #pragma shader_feature_local _ _DETAIL_MULX2 _DETAIL_SCALED
              #pragma shader_feature_local_fragment _SPECGLOSSMAP
              #pragma shader_feature EDITOR_VISUALIZATION
  
              // -------------------------------------
              // Includes
              #include "Packages/com.unity.render-pipelines.universal/Shaders/LitInput.hlsl"
              #include "Packages/com.unity.render-pipelines.universal/Shaders/LitMetaPass.hlsl"
  
              ENDHLSL
          }
  
          Pass
          {
              Name "Universal2D"
              Tags
              {
                  "LightMode" = "Universal2D"
              }
  
              // -------------------------------------
              // Render State Commands
              Blend[_SrcBlend][_DstBlend]
              ZWrite[_ZWrite]
              Cull[_Cull]
  
              HLSLPROGRAM
              #pragma target 2.0
  
              // -------------------------------------
              // Shader Stages
              #pragma vertex vert
              #pragma fragment frag
  
              // -------------------------------------
              // Material Keywords
              #pragma shader_feature_local_fragment _ALPHATEST_ON
              #pragma shader_feature_local_fragment _ALPHAPREMULTIPLY_ON
  
              #include_with_pragmas "Packages/com.unity.render-pipelines.universal/ShaderLibrary/DOTS.hlsl"
  
              // -------------------------------------
              // Includes
              #include "Packages/com.unity.render-pipelines.universal/Shaders/LitInput.hlsl"
              #include "Packages/com.unity.render-pipelines.universal/Shaders/Utils/Universal2D.hlsl"
              ENDHLSL
          }
      }
  
      FallBack "Hidden/Universal Render Pipeline/FallbackError"
      CustomEditor "UnityEditor.Rendering.Universal.ShaderGUI.LitShader"
  }
  

‌RenderFeature配置要点‌：

• 需创建URP Renderer Feature
• 设置Layer Mask匹配目标层级
• 在后处理前添加Pass

‌多Pass深度测试法‌：

Pass {
    ZTest Greater
    ZWrite On
    ColorMask 0
}
Pass {
    ZTest LEqual
    // 正常渲染...
}

‌UGUI Mask混合方案‌：

• 使用RectTransform确定遮罩区域
• 通过第二摄像机渲染3D物体
• 结合UI Mask组件控制显示范围

‌RenderTexture遮罩‌：

• 创建临时RenderTexture
• 使用特定Shader渲染遮罩通道
• 通过后期处理合成最终效果

模板测试适合需要精确控制像素级显示的场景，而多Pass方案更适合简单的遮挡提示效果

【从UnityURP开始探索游戏渲染】专栏-直达

（欢迎点赞留言探讨，更多人加入进来能更加完善这个探索的过程，????）