Unity Shader 实现雨天的水面涟漪效果

Shader 
"Custom/Ripple" {

  Properties {

    _Color (
"Color", Color) = (
1,
1,
1,
1)

    _MainTex (
"Albedo (RGB)", 
2D) = 
"white" {}

    _Glossiness (
"Smoothness", Range(
0,
1)) = 
0.5

    _Metallic (
"Metallic", Range(
0,
1)) = 
0.0

    _RippleTex(
"RippleTex", 
2D) = 
"white" {}

    _RippleScale(
"RippleScale",Range(
1,
10)) =
1





  }

  SubShader {

    Tags { 
"RenderType"=
"Opaque" }

    LOD 
200





    CGPROGRAM

    
// Physically based Standard lighting model, and enable shadows on all light types

    
#
pragma surface surf Standard fullforwardshadows

    
#
pragma target 3.0

    
#
define PI 3.141592653

    sampler2D _MainTex;





    
struct Input {

      float2 uv_MainTex;

      half2 texcoord;

    };





    half _Glossiness;

    half _Metallic;

    fixed4 _Color;

    sampler2D _RippleTex;

    
float _RippleScale;

    UNITY_INSTANCING_BUFFER_START(Props)

    UNITY_INSTANCING_BUFFER_END(Props)





    
//计算波纹的主函数

    
float3 
ComputeRipple(
float2 uv, 
float t)

    {

      
//波纹贴图采样，并把采样的高度值扩展到-1到1。

      float4 ripple = tex2D(_RippleTex, uv);

      ripple.yz = ripple.yz * 
2.0 - 
1.0;

      
//获取波纹的时间,从A通道获取不同的波纹时间,

      
float dropFrac = frac(ripple.a + t);

      
//把时间限制在R通道内

      
float timeFrac = dropFrac - 
1.0 + ripple.x;

      
//做淡出处理

      
float dropFactor = 
1-saturate( dropFrac);

      
//计算最终的高度，用一个sin计算出随时间的振幅，修改一下值就知道什么效果了

      
float final = dropFactor* sin(clamp(timeFrac * 
9.0, 
0.0, 
4.0) * PI);

      
return float3(ripple.yz * final, 
1.0);

    }





    

void 
surf (
Input IN, inout SurfaceOutputStandard o) {

      fixed4 c = tex2D (_MainTex, IN.uv_MainTex) * _Color;

      o.Albedo = c.rgb;





      
//调用方法，获取高度。这里我懒得用一个新uv，索性直接用的主贴图UV

      float3 ripple = ComputeRipple(IN.uv_MainTex / _RippleScale, _Time.y);

      
// Metallic and smoothness come from slider variables

      o.Metallic = _Metallic;

      o.Smoothness = _Glossiness;

      
//赋值到法线上

      o.Normal = ripple;

      o.Alpha = c.a;

    }

    ENDCG

  }

  FallBack 
"Diffuse"

}