Flow Map Shader for Unity3D. Used with Sprites.

Shader "Custom/Flow Map" { Properties { [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {} _Color ("Tint", Color) = (1,1,1,1) // Flow _FlowMap ("Flow Map", 2D) = "white" {} _FlowSpeed ("Flow Speed", float) = 0.05

    [MaterialToggle] PixelSnap ("Pixel snap", Float) = 0
}

SubShader
{
    Tags
    { 
        "Queue"="Transparent" 
        "IgnoreProjector"="True" 
        "RenderType"="Transparent" 
        "PreviewType"="Plane"
        "CanUseSpriteAtlas"="True"
    }

    Cull Off
    Lighting Off
    ZWrite Off
    Blend One OneMinusSrcAlpha

    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;
        };
        
        fixed4 _Color;

        v2f vert(appdata_t IN)
        {
            v2f OUT;

            OUT.vertex = mul(UNITY_MATRIX_MVP, IN.vertex);
            OUT.texcoord = IN.texcoord;
            OUT.color = IN.color * _Color;
            #ifdef PIXELSNAP_ON
            OUT.vertex = UnityPixelSnap (OUT.vertex);
            #endif

            return OUT;
        }

        sampler2D _MainTex;
        sampler2D _FlowMap;
        float _FlowSpeed;

        fixed4 frag(v2f IN) : SV_Target
        {
            float3 flowDir = tex2D(_FlowMap, IN.texcoord) * 2.0f - 1.0f;
            flowDir *= _FlowSpeed;

            float phase0 = frac(_Time[1] * 0.5f + 0.5f);
            float phase1 = frac(_Time[1] * 0.5f + 1.0f);

            half3 tex0 = tex2D(_MainTex, IN.texcoord + flowDir.xy * phase0);
            half3 tex1 = tex2D(_MainTex, IN.texcoord + flowDir.xy * phase1);

            float flowLerp = abs((0.5f - phase0) / 0.5f);
            half3 finalColor = lerp(tex0, tex1, flowLerp);

            fixed4 c = float4(finalColor, 1.0f) * IN.color;
            c.rgb *= c.a;
            return c;
        }
        ENDCG
    }
}

}