UI-AdditiveFlow

Shader "Custom/UI/AdditiveFlow"
{
    Properties
    {
        _MainTex ("Sprite Texture", 2D) = "white" {}
        _Color ("Tint", Color) = (1,1,1,1)

        _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

        [Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip ("Use Alpha Clip", Float) = 0

        _FlowTex("Flow Texture", 2D) = "grey" {}
        _XMul ("UV.x mul", float) = 0.25
        _YMul ("UV.y mul", float) = 0.25
        _Speed ("Speed", float) = 0.05
    }

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

        Stencil
        {
            Ref [_Stencil]
            Comp [_StencilComp]
            Pass [_StencilOp]
            ReadMask [_StencilReadMask]
            WriteMask [_StencilWriteMask]
        }

        Cull Off
        Lighting Off
        ZWrite Off
        ZTest [unity_GUIZTestMode]
        Blend SrcAlpha OneMinusSrcAlpha
        ColorMask [_ColorMask]

        Pass
        {
        CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"
            #include "UnityUI.cginc"

            #pragma multi_compile __ UNITY_UI_ALPHACLIP

            struct appdata_t
            {
                float4 vertex   : POSITION;
                float4 color    : COLOR;
                float2 texcoord : TEXCOORD0;
                float2 flowcoord : TEXCOORD1;
            };

            struct v2f
            {
                float4 vertex   : SV_POSITION;
                fixed4 color    : COLOR;
                half2 texcoord  : TEXCOORD0;
                float2 flowcoord : TEXCOORD1;
                float4 worldPosition : TEXCOORD2;
            };

            fixed4 _Color;
            fixed4 _TextureSampleAdd;
            float4 _ClipRect;

            v2f vert(appdata_t IN)
            {
                v2f OUT;
                OUT.worldPosition = IN.vertex;
                OUT.vertex = mul(UNITY_MATRIX_MVP, OUT.worldPosition);

                //OUT.texcoord = TRANSFORM_TEX(IN.texcoord, _MainTex);
                OUT.texcoord = IN.texcoord;

                #ifdef UNITY_HALF_TEXEL_OFFSET
                OUT.vertex.xy += (_ScreenParams.zw-1.0)*float2(-1,1);
                #endif

                //OUT.flowcoord = TRANSFORM_TEX(IN.flowcoord, _FlowTex);
                OUT.flowcoord = IN.flowcoord;

                OUT.color = IN.color * _Color;
                return OUT;
            }

            uniform sampler2D _MainTex;
            uniform float4 _MainTex_ST;
            uniform sampler2D _FlowTex;
            uniform float4 _FlowTex_ST;
            uniform fixed _XMul;
            uniform fixed _YMul;
            uniform fixed _Speed;

            fixed4 frag(v2f IN) : SV_Target
            {
                fixed phase = _Time[1];
                fixed2 flowDir = fixed2(_XMul, _YMul) * _Speed;
                fixed2 flowUV = IN.flowcoord + flowDir * phase;
                fixed4 tex1 = tex2D(_FlowTex, flowUV);
                fixed4 tex0 = tex2D(_MainTex, IN.texcoord);

                fixed4 add = tex1 < .5 ? 2.0 * tex1 * tex0 : 1.0 - 2.0 * (1.0 - tex1) * (1.0 - tex0); //additive calc

                fixed4 c = (add + _TextureSampleAdd) * IN.color;

                c.a *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);

                #ifdef UNITY_UI_ALPHACLIP
                clip (c.a - 0.001);
                #endif

                return c;
            }
        ENDCG
        }
    }
}