Unity Shader之流光效果

流光效果，支持控制流光宽度，颜色，角度

• URP版本

  Shader "Unlit/LightFlow"
  {
      Properties
      {
          _MainTex ("Texture", 2D) = "white" {}
          _LightColor ("Light", Color) = (1,1,1,1)
          _LightWidth ("Light width", float) = 0.2
          _LightAngle ("Light angle", float) = 45
          _LightRange("Light range", float) = 0
  
          _StencilComp ("Stencil Comparison", Float) = 8
          _Stencil ("Stencil ID", Float) = 0
          _StencilOp ("Stencil Operation", Float) = 0
          _StencilWriteMask ("Stencil Write Mask", Float) = 255
          _StencilReadMask ("Stencil Read Mask", Float) = 255
  
      }
      SubShader
      {
          Tags { "RenderType"="Transparent" "Queue"="Transparent" }
          Stencil
          {
              Ref [_Stencil]
              Comp [_StencilComp]
              Pass [_StencilOp] 
              ReadMask [_StencilReadMask]
              WriteMask [_StencilWriteMask]
          }
  
          Cull Off
          Lighting Off
          ZWrite Off
          ZTest [unity_GUIZTestMode]
          Blend SrcAlpha OneMinusSrcAlpha
  
          Pass
          {
              HLSLINCLUDE
              #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/core.hlsl"
              ENDHLSL
  
              HLSLPROGRAM
              #pragma vertex vert
              #pragma fragment frag
  
  
              struct appdata
              {
                  float4 vertex : POSITION;
                  float2 uv : TEXCOORD0;
              };
  
              struct v2f
              {
                  float2 uv : TEXCOORD0;
                  float4 vertex : SV_POSITION;
              };
  
              sampler2D _MainTex;
              float4 _MainTex_ST;
              uniform float4 _LightColor;
              float _LightWidth;
              float _LightAngle;
              float _LightRange;
  
              v2f vert (appdata v)
              {
                  v2f o;
                  o.vertex = TransformObjectToHClip(v.vertex);
                  o.uv = TRANSFORM_TEX(v.uv, _MainTex);
                  return o;
              }
  
  
              real4 frag (v2f i) : SV_Target
              {
                  real4 col = tex2D(_MainTex, i.uv);
  
                  float angle = radians(_LightAngle);
                  float halfWidth = _LightWidth / 2 / cos(angle);
  
                  float base = tan(angle) * i.uv.x + _LightRange;
                  float up = base + halfWidth;
                  float down = base - halfWidth ;
                  float pwidth = length(float2(ddx(i.uv.x), ddy(i.uv.y))) * 30;
  
                  float4 light = (smoothstep(up, up + pwidth, i.uv.y) - smoothstep(down - pwidth, down , i.uv.y)) *  _LightColor;
                  col.rgb = col.rgb + light.rgb * light.a;
  
  
                  return col;
              }
              ENDHLSL
          }
      }
  }
  

• 内置管线版本

  Shader "Unlit/FlowLight"
  {
      Properties
      {
          _MainTex ("Texture", 2D) = "white" {}
          _LightColor ("Light", Color) = (1,1,1,1)
  
          _StencilComp ("Stencil Comparison", Float) = 8
          _Stencil ("Stencil ID", Float) = 0
          _StencilOp ("Stencil Operation", Float) = 0
          _StencilWriteMask ("Stencil Write Mask", Float) = 255
          _StencilReadMask ("Stencil Read Mask", Float) = 255
  
      }
      SubShader
      {
          Tags { "RenderType"="Transparent" "Queue"="Transparent" }
          Stencil
          {
              Ref [_Stencil]
              Comp [_StencilComp]
              Pass [_StencilOp] 
              ReadMask [_StencilReadMask]
              WriteMask [_StencilWriteMask]
          }
  
          Cull Off
          Lighting Off
          ZWrite Off
          ZTest [unity_GUIZTestMode]
          Blend SrcAlpha OneMinusSrcAlpha
  
          Pass
          {
              CGPROGRAM
              #pragma vertex vert
              #pragma fragment frag
              // make fog work
              #pragma multi_compile_fog
  
              #include "UnityCG.cginc"
  
              struct appdata
              {
                  float4 vertex : POSITION;
                  float2 uv : TEXCOORD0;
              };
  
              struct v2f
              {
                  float2 uv : TEXCOORD0;
                  UNITY_FOG_COORDS(1)
                  float4 vertex : SV_POSITION;
              };
  
              sampler2D _MainTex;
              float4 _MainTex_ST;
              uniform float4 _LightColor;
  
              v2f vert (appdata v)
              {
                  v2f o;
                  o.vertex = UnityObjectToClipPos(v.vertex);
                  o.uv = TRANSFORM_TEX(v.uv, _MainTex);
                  return o;
              }
  
  
              fixed4 frag (v2f i) : SV_Target
              {
                  fixed4 col = tex2D(_MainTex, i.uv);
                  float base =((_Time.z)%4/4 - 0.1)*1.2;
                  float up = base + sin(i.uv.x * 0.2) * 0.01;
                  float down =base - 0.08+ sin(i.uv.x * 0.66)* 0.01;
                  float pwidth = length(float2(ddx(i.uv.x), ddy(i.uv.y))) * 30;
                  float4 wave = (smoothstep(up, up - pwidth, i.uv.y)-smoothstep(down, down - pwidth, i.uv.y))* _LightColor;
                  col.rgb = col.rgb +  wave/3 ;
                  return col;
              }
              ENDCG
          }
      }
  }