Unity shader实现移动端模拟深度水效果

本文实例为大家分享了Unity shader实现移动端模拟深度水的具体代码，供大家参考，具体内容如下

描述：

在网上看到很多效果很好的水，比如根据水的深度，颜色有深浅变化，能让水变得更真实，但是又会涉及到比较复杂的计算，在移动端上面还是有些吃力的。

最近研究了一下，想在移动端上面模拟这样的效果 ：

1 水的深浅透明度变化

2 水的深浅颜色变化

3 水上的阴影模拟（大面积的水通过烘焙比较浪费烘焙图）

根据上面的3点，可以通过一张黑白图的rg通道来实现深浅以及阴影的模拟 效果如下

如图，浅色的偏绿，深色的偏蓝 ，颜色可以手动调节，左边为阴影位置

代码如下：

Shader "Game_XXX/whater"
{
 Properties
 {
 _WaterTex ("Normal Map (RGB), Foam (A)", 2D) = "white" {}
 _AlphaTex("AlphaTex", 2D) = "black" {}
 _shadowLight ("shadowLight",range(0,1)) = 0
 _Tiling ("Wave Scale", Range(0.00025, 0.007)) = 0.25
 _WaveSpeed("Wave Speed", Float) = 0.4
 _SpecularRatio ("Specular Ratio", Range(10,500)) = 200
 _outSideColor("outSideColor",Color) = (0,0,0,0)
 _outSideLight("outSideLight",Range(0,10))=1
 _inSideColor("inSideColor",Color) = (0,0,0,0)
 _inSideLight("intSideLight",Range(0,10))=1
 _Alpha("Alpha",Range(0,1)) = 1
 //模拟灯光颜色
 _LightColorSelf ("LightColorSelf",Color) = (1,1,1,1)
 //模拟灯光方向
 _LightDir ("LightDir",vector) = (0,1,0,0)
 //高光强度
 _specularLight("specularLight",range(0.1,2)) =1
 }

 SubShader {
 Tags {
  "Queue"="Transparent-200"
  "RenderType"="Transparent"
  "IgnoreProjector" = "True"
  "LightMode" = "ForwardBase"
 }
 LOD 250
 Pass
 {

  ZWrite Off
  Blend SrcAlpha OneMinusSrcAlpha
  CGPROGRAM

  #pragma vertex Vert
  #pragma fragment Frag
  #include "UnityCG.cginc"

  float _Tiling;
  float _WaveSpeed;
  float _SpecularRatio;
  sampler2D _WaterTex;
  sampler2D _AlphaTex;
  float4 _LightColorSelf;
  float4 _LightDir;
  float4 _outSideColor;
  float _outSideLight;
  float4 _inSideColor;
  float _inSideLight;
  float _shadowLight;
  float _specularLight;
  float _Alpha;

  struct v2f
  {
  float4 position : POSITION;
  float3 worldView : TEXCOORD0;
  float3 tilingAndOffset:TEXCOORD2;
  float3x3 tangentTransform:TEXCOORD4;
  float2 alphaUV :TEXCOORD7;

  };

  v2f Vert(appdata_full v)
  {
  v2f o;
  float4 worldPos = mul(unity_ObjectToWorld, v.vertex);
  //视向量（世界空间）
  o.worldView = -normalize(worldPos - _WorldSpaceCameraPos);
  o.position = UnityObjectToClipPos(v.vertex);
  //uv动画
  o.tilingAndOffset.z =frac( _Time.x * _WaveSpeed);//frac :返回标量或矢量的小数
  o.tilingAndOffset.xy = worldPos.xz*_Tiling;
  o.alphaUV = v.texcoord;
  //求世界法线三件套
  float3 normal =normalize( UnityObjectToWorldNormal(v.normal));
       float3 tangentDir = normalize( mul( unity_ObjectToWorld, float4( v.tangent.xyz, 0.0 ) ).xyz );//切线空间转化为世界空间
       float3 bitangentDir = normalize(cross(normal, tangentDir) * v.tangent.w);//切线 法线 计算副切线 

  o.tangentTransform = float3x3( tangentDir, bitangentDir, normal);
  return o;
  }

  float4 Frag(v2f i):COLOR
  {

   //法线采样
   fixed3 BumpMap01 = UnpackNormal(tex2D(_WaterTex,i.tilingAndOffset.xy + i.tilingAndOffset.z ));
   fixed3 BumpMap02 = UnpackNormal(tex2D(_WaterTex,i.tilingAndOffset.xy*1.1 - i.tilingAndOffset.z));
   //两张法线相混合
   //fixed3 N1 =saturate( normalize(mul( BumpMap01.rgb, i.tangentTransform )));
   //fixed3 N2 =saturate( normalize(mul( BumpMap02.rgb, i.tangentTransform )));
   //fixed3 worldNormal = N1 - float3(N2.x,0,N2.z);

   fixed3 N1 = normalize(mul( BumpMap01.rgb, i.tangentTransform ));
   fixed3 N2 = normalize(mul( BumpMap02.rgb, i.tangentTransform ));
   fixed3 worldNormal = N1*0.5 +N2*0.5;

   float LdotN = dot(worldNormal, _LightDir.xyz); //_LightDir为模拟灯光

   //高光
   float dotSpecular = dot(worldNormal, normalize( i.worldView+_LightDir.xyz));
   fixed3 specularReflection = pow(saturate(dotSpecular), _SpecularRatio)*_specularLight;

   //通道贴图采样
   fixed4 alphaTex = tex2D (_AlphaTex,i.alphaUV);
   //模拟灯光的颜色 * 漫反射系数= 基础水的颜色
   fixed4 col =_LightColorSelf*2 * saturate (LdotN) ;
   //用alpha贴图的r通道来模拟水的深浅的颜色，白色为深色，黑色为浅色 ，同时乘以想要的颜色
   col.rgb = col.rgb * alphaTex.r *_inSideColor * _inSideLight + col.rgb * (1-alphaTex.r) * _outSideColor *_outSideLight + specularReflection;

   //控制透明度，根据alpha的r通道 来控制深浅的透明度，深色的透明度小 浅色的透明度大
   col.a = _Alpha * alphaTex.r;

   //手动绘制阴影 用alpha贴图的g通道 跟col相乘 来模拟阴影
   alphaTex.g = saturate(alphaTex.g + _shadowLight);
   col.rgb *= alphaTex.g;
   return col;
  }
    ENDCG
   }
 }

 FallBack "Diffuse"
}

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