一、工程截图

二、控制水底波的Shader

//水底光影效果
Shader "Custom/UnderwaterLightShadow"
{
    Properties
    {
        //水底纹理
        _MainTex ("Texture", 2D) = "white" {}
        //光影灰度图
        _LightTex("Light Shadow", 2D) = "white" {}
        //光影颜色
        _LightColor("Light Color", Color) = (1,1,1,1)
        //频率(X轴方向)
        _FrequencyX("FrequencyX", float) = 2
        //频率(Y轴方向)
        _FrequencyY("FrequencyY", float) = 2
        //波动周期(X轴方向)
        _CycleX("CycleX", float) = 10
        //波动周期(Y轴方向)
        _CycleY("CycleY", float) = 10
        //波动幅度(X轴方向)
        _AmplitudeX("AmplitudeX", float) = 0.003
        //波动幅度(Y轴方向)
        _AmplitudeY("AmplitudeY", float) = 0.003
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 100

        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;

            sampler2D _LightTex;
            float4 _LightTex_ST;

            float4 _LightColor;
            float _FrequencyX;
            float _FrequencyY;
            float _CycleX;
            float _CycleY;
            float _AmplitudeX;
            float _AmplitudeY;

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv, _MainTex);
                UNITY_TRANSFER_FOG(o,o.vertex);
                return o;
            }

            fixed4 frag(v2f i) : SV_Target
            {
                //控制光影图像素偏移
                float2 uv_offset = float2(0,0);
                //水平震动
                uv_offset.x = sin(_FrequencyX * _Time.y + _CycleY * i.uv.y * UNITY_TWO_PI) * _AmplitudeX;
                //垂直震动
                uv_offset.y = sin(_FrequencyY * _Time.y + _CycleX * i.uv.x * UNITY_TWO_PI) * _AmplitudeY;
                //处理Tiling和Offset
                float2 uv = i.uv * _LightTex_ST.xy + _LightTex_ST.zw;
                //纹理采样
                fixed4 light_color = tex2D(_LightTex, uv + uv_offset) * _LightColor;

                // sample the texture
                fixed4 col = tex2D(_MainTex, i.uv) + light_color;
                // apply fog
                UNITY_APPLY_FOG(i.fogCoord, col);
                return col;
            }
            ENDCG
        }
    }
}

运行效果