Unity 水纹/溶解 Shader

如下：

Shader "A/WaveShader"
{
    Properties
    {
        _MainTex("MainTex", 2D) = "white"{}
        _NoiseTex("NoiseTex", 2D) = "white"{}
        _Cutout("Cutout", Range(-0.1, 1.1)) = 0.0
        _Speed("Speed", Vector) = (1, 1, 0, 0)
    }
    SubShader
    {
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

            struct appdata
            {
                float4 vertex: POSITION;
                float2 uv: TEXCOORD0;
            };

            struct v2f
            {
                float4 pos: SV_POSITION;
                float2 uv: TEXCOORD0;
            };

            sampler2D _MainTex;
            sampler2D _NoiseTex;
            float _Cutout;
            float4 _Speed;

            v2f vert(appdata v)
            {
                v2f o;
                float4 pos_clip = UnityObjectToClipPos(v.vertex);
                o.pos = pos_clip;
                o.uv = v.uv;
                return o;
            }

            half4 frag(v2f i) : SV_Target
            {
                half gradient = tex2D(_MainTex, i.uv + _Time.y * _Speed.xy).r;
                half noise = tex2D(_NoiseTex, i.uv + _Time.y * _Speed.zw).r;
                clip(gradient - noise - _Cutout);
                return noise.xxxx;
            }

            ENDCG
        }
    }
}