在UV流动的同时，加入正弦函数扰动，由于美术要求图片重用，所以添加轮廓剪切，支持UI裁剪，叠加区域编辑。

效果：

代码如下：

Shader "UI/Unlit/AddFlowTex"{    Properties    {        [PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}        _Color("Tint", Color) = (1, 1, 1, 1)        [MaterialToggle] PixelSnap("Pixel snap", float) = 0        /* UI */        _StencilComp("Stencil Comparison", Float) = 8        _Stencil("Stencil ID", Float) = 0        _StencilOp("Stencil Operation", Float) = 0        _StencilWriteMask("Stencil Write Mask", Float) = 255        _StencilReadMask("Stencil Read Mask", Float) = 255        _ColorMask("Color Mask", Float) = 15        /* -- */    }        SubShader    {        Tags    {        "Queue" = "Transparent"        "IgnoreProjector" = "True"        "RenderType" = "Transparent"        "PreviewType" = "Plane"        "CanUseSpriteAtlas" = "True"    }        Cull Off        Lighting Off        ZWrite Off        Blend One OneMinusSrcAlpha        ColorMask[_ColorMask]        /* UI */        Stencil    {        Ref[_Stencil]        Comp[_StencilComp]        Pass[_StencilOp]        ReadMask[_StencilReadMask]        WriteMask[_StencilWriteMask]    }        /* -- */        Pass    {        CGPROGRAM#pragma vertex vert#pragma fragment frag#pragma multi_compile _ PIXELSNAP_ON#include "UnityCG.cginc"        struct appdata_t    {        float4 vertex : POSITION;        float4 color : COLOR;        float2 texcoord : TEXCOORD0;    };    struct v2f    {        float4 vertex : SV_POSITION;        fixed4 color : COLOR;        half2 texcoord : TEXCOORD0;        float4 worldPosition: TEXCOORD1;    };    fixed4 _Color;    v2f vert(appdata_t IN)    {        v2f OUT;        OUT.worldPosition = IN.vertex;        OUT.vertex = UnityObjectToClipPos(IN.vertex);        OUT.texcoord = IN.texcoord;        OUT.color = IN.color * _Color;#ifdef PIXELSNAP_ON        OUT.vertex = UnityPixelSnap(OUT.vertex);#endif        return OUT;    }    sampler2D _MainTex;    float4 _MainTex_ST;    /* FlowTex */    sampler2D _FlowTex;    float _MoveSpeed;    float _AmScale;    fixed4 _FlowlightColor;    float _Width;    /* --------- */    //如果使用图集中的图片，需要设置一下参数    float _WidthRate;    float _XOffset;    float _HeightRate;    float _YOffset;    float2 _Tiling;    bool _UseClipRect;    float4 _ClipRect;    float _ClipSoftX;    float _ClipSoftY;    fixed4 frag(v2f IN) : SV_Target    {        fixed4 c = tex2D(_MainTex, IN.texcoord);        /*使用裁剪*/        if (_UseClipRect)        {            float2 factor = float2(0.0, 0.0);            float2 tempXY = (IN.worldPosition.xy - _ClipRect.xy) / float2(_ClipSoftX, _ClipSoftY)*step(_ClipRect.xy, IN.worldPosition.xy);            factor = max(factor, tempXY);            float2 tempZW = (_ClipRect.zw - IN.worldPosition.xy) / float2(_ClipSoftX, _ClipSoftY)*step(IN.worldPosition.xy, _ClipRect.zw);            factor = min(factor, tempZW);            c.a *= clamp(min(factor.x, factor.y), 0.0, 1.0);        }        /* --------- */        /* FlowTex*/        //将UV由图集中的变换到0-1        float2 uv = (IN.texcoord - float2(_XOffset, _YOffset)) / float2(_WidthRate, _HeightRate);        //添加正弦扰动        float offsetY = sin(uv.x * 6.28)*_AmScale;        uv = (uv + float2(_Time.x*_MoveSpeed, offsetY))*_Tiling;        //轮廓的限制，以0.5为中心，上下扩展        fixed temp = step(abs(uv.y - 0.5*_Tiling.y), _Width*0.5*_Tiling.y);        //对烟雾图进行采样        fixed4 cadd = tex2D(_FlowTex,uv)*temp;        /*        //使用blend src，1-src        c.rgb = cadd.rgb*cadd.a* _FlowlightColor +c.rgb*(1-cadd.a);        */        //使用blend add        c.rgb = cadd.rgb*cadd.a* _FlowlightColor + c.rgb;        /* --------- */        c.rgb *= c.a;        return c;    }        ENDCG    }    }}

代码中有注释，就不多做解释了。这个shader有几个特点：

1、支持UGUI裁剪，在ScrollView中可用。

2、支持叠加图片的编辑，可以重用游戏中的资源，可填充颜色和Tiling限制采样区域。

3、支持叠加区域的编辑，由于只写了横向移动，所以只能编辑纵向的区域。

4、UV流动的同时，纵向UV扰动，让效果更自然，并且按照扰动编辑叠加区域。