Unity水面Shader实现详解

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Unity水面Shader实现详解

引用

来源

https://bbs.huaweicloud.com/blogs/442614

在Unity中实现逼真的水面效果是许多游戏开发者追求的目标。本文将详细介绍如何通过编写自定义Shader来实现这一效果，包括具体的代码实现和材质设置步骤。

效果预览

Shader代码实现

首先，创建一个新的Shader文件，并命名为"Custom/WaterShader"。以下是完整的Shader代码：

Shader "Custom/WaterShader"
{
    Properties {
        _WaterTex ("Normal Map (RGB), Foam (A)", 2D) = "white" {}
        _WaterTex2 ("Normal Map (RGB), Foam (B)", 2D) = "white" {}
 
        _Tiling ("Wave Scale", Range(0.00025, 0.1)) = 0.25
        _WaveSpeed("Wave Speed", Float) = 0.4
        _SpecularRatio ("Specular Ratio", Range(10,500)) = 200
 
        _BottomColor("Bottom Color",Color) = (0,0,0,0)
        _TopColor("Top Color",Color) = (0,0,0,0)
        _Alpha("Alpha",Range(0,1)) = 1
 
        _ReflectionTex("_ReflectionTex", 2D) = "black" {}
        _ReflectionLight("ReflectionLight",Range(0,1)) = 0.3
 
        _LightColorSelf ("LightColorSelf",Color) = (1,1,1,1)
        _LightDir ("LightDir",vector) = (0,1,0,0)
    }
    
    SubShader {  
        Tags {
            "Queue"="Transparent-200"
            "RenderType"="Transparent" 
            "IgnoreProjector" = "True"
            "LightMode" = "ForwardBase"
        }
        LOD 250
        Pass{
            Lighting On
            ZWrite On
            Blend SrcAlpha OneMinusSrcAlpha
            CGPROGRAM
 
            #pragma vertex Vert
            #pragma fragment Frag
            #include "UnityCG.cginc"
            
             float _Tiling;
             float _WaveSpeed;
             float _SpecularRatio;
             sampler2D _WaterTex;
             sampler2D _WaterTex2;
             sampler2D _ReflectionTex;
             float4 _LightColorSelf;
             float4 _LightDir;
             float4 _BottomColor;
             float4 _TopColor;
             float _Alpha;
             float _ReflectionLight;
            struct v2f
            {
             float4 position  : POSITION;
             float3 worldPos  : TEXCOORD0;
             float3 tilingAndOffset:TEXCOORD2;
             float4 screen:TEXCOORD3;
             float4 VertColor :TEXCOORD4;
 
            };
            v2f Vert(appdata_full v)
            {
             v2f o;
             o.worldPos = mul(unity_ObjectToWorld, v.vertex);
             o.position = UnityObjectToClipPos(v.vertex);
             //uv动画
             o.tilingAndOffset.z =frac( _Time.x * _WaveSpeed);
             o.tilingAndOffset.xy = o.worldPos.xz*_Tiling;
             o.screen = ComputeScreenPos(o.position);
             o.VertColor = v.color;
             return o;
            }
            float4 Frag(v2f i):COLOR
            {
              float3 lightColor=_LightColorSelf.rgb*2;
              //世界视向量
              float3 worldView = -normalize(i.worldPos - _WorldSpaceCameraPos);
              float2 tiling = i.tilingAndOffset.xy;
              //法线采样
              float4 N1 = tex2D(_WaterTex, tiling.yx +float2(i.tilingAndOffset.z,0));
              float4 N2 = tex2D(_WaterTex2, tiling.yx -float2(i.tilingAndOffset.z,0));
              //两个法线相加，转世界空间，这里没有unpack,所以法线贴图不需要转normal  法线贴图为0-1 两张加起来为0-2 将其x2-2，转换为-2 --2然后将其normalize，变成-1到1
              //在遇到两张法线的情况下 ，一般将法线相加 再normalize
              float3 worldNormal  = normalize((N1.xyz+N2.xyz)*2-2);
              //以垂直的方向代替灯光 跟法线做点积 得到漫反射强度
              float LdotN = dot(worldNormal, float3(0,1,0));
              fixed2 uv = i.screen.xy/(i.screen.w+0.0001);
              uv.y = 1-uv.y;
              fixed4 refTex = tex2D (_ReflectionTex,uv + worldNormal.xy*0.02 );
              //这个变量一般在Forward渲染路径下使用，存储的是重要的pixel光源方向，没错，的确是使用w来判断这个光源的类型的，一般和_LightColor0配合使用
              //float3 LView=_WorldSpaceLightPos0.xyz;
              float3 LView = _LightDir.xyz;
 
                 //if(_WorldSpaceLightPos0.w == 0.0){ 
                    // L = normalize(_WorldSpaceLightPos0.xyz); 
                    // } 
                    // else{ 
                    // L = normalize(_WorldSpaceLightPos0.xyz - i.worldPos); 
                    // } 
                //根据世界法线 ，世界视向量+光向量  得出高光 系数
                float dotSpecular = dot(worldNormal,  normalize( worldView+LView));
                //控制高光的范围
                float3 specularReflection = pow(saturate(dotSpecular), _SpecularRatio);
              float4 col;
              float fresnel = 0.5*LdotN+0.5;
              //根据法线的强度 来确定两种颜色之间的混合 ？？？？
              col.rgb  = lerp(_BottomColor.xyz, _TopColor.xyz, fresnel);
             
              col.rgb = saturate (LdotN) *col.rgb;
              //加上高光
              col.rgb += specularReflection;
              col.rgb = lerp (col.rgb,refTex.rgb*_ReflectionLight,0.7);
              //col.rgb +=refTex.rgb*_ReflectionLight;
              //加上灯光颜色
              col.rgb*=lightColor;
              col.rgb *= i.VertColor.rgb;
              //控制透明度
              
              col.a =i.VertColor.a * _Alpha;
              return col;
            }
 
        ENDCG    
        }  
 
    }
 
    FallBack "Diffuse"
}