Unity Marching Ants Sprite Outline Shader

// original source: https://github.com/wlgys8/Sprites-Outline

Shader "Sprites/Outline (Marching Ants)" { Properties { [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {} _Color ("Tint", Color) = (1,1,1,1) [MaterialToggle] PixelSnap ("Pixel snap", Float) = 0

    // Add values to determine if outlining is enabled and outline color.
    [PerRendererData] _OutlineSize ("Outline", Float) = 0
    [PerRendererData] _OutlineColor("Outline Color", Color) = (1,1,1,1)
}

CGINCLUDE
#include "UnityCG.cginc"

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

struct v2f
{
    float4 vertex   : SV_POSITION;
    fixed4 color    : COLOR;
    float2 texcoord  : TEXCOORD0;
};
fixed4 _Color;

v2f vert_outline(appdata_t IN)
{
    v2f OUT;
    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;
sampler2D _AlphaTex;

float4 _MainTex_TexelSize; //magic var
float _OutlineSize; //outline size
fixed4 _OutlineColor; // outlie color

fixed4 SampleSpriteTexture (float2 uv)
{
    fixed4 color = tex2D (_MainTex, uv);
    return color;
}

ENDCG

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

    Cull Off
    Lighting Off
    ZWrite Off
    Blend One OneMinusSrcAlpha

    //outline down
    Pass
    {
   		Offset 1, 1

        CGPROGRAM
        #pragma vertex vert
        #pragma fragment frag
        #pragma multi_compile _ PIXELSNAP_ON
        #pragma shader_feature ETC1_EXTERNAL_ALPHA

        v2f vert(appdata_t IN)
        {
        	return vert_outline(IN);
        }

        fixed4 frag(v2f IN) : SV_Target
        {
           	fixed4 texColor = SampleSpriteTexture (IN.texcoord + fixed2(0,_MainTex_TexelSize.y*_OutlineSize)) * IN.color;
           	fixed4 c = _OutlineColor * texColor.a;
    				int w = ((int)(IN.texcoord.x * 100 + IN.texcoord.y * 100 + _Time.y * 5) & 1);
            return c*w;
        }
        ENDCG
    }

    //outline up
    Pass
    {
   		Offset 1, 1

        CGPROGRAM
        #pragma vertex vert
        #pragma fragment frag
        #pragma multi_compile _ PIXELSNAP_ON
        #pragma shader_feature ETC1_EXTERNAL_ALPHA

        v2f vert(appdata_t IN)
        {
        	return vert_outline(IN);
        }

        fixed4 frag(v2f IN) : SV_Target
        {

           	fixed4 texColor = SampleSpriteTexture (IN.texcoord + fixed2(0,- _MainTex_TexelSize.y* _OutlineSize)) * IN.color;
           	fixed4 c = _OutlineColor * texColor.a;
            int w = ((int)(IN.texcoord.x * 100 + IN.texcoord.y * 100 + _Time.y * 5) & 1);
            return c*w;
        }
        ENDCG
    }

    //outline left
    Pass
    {
   		Offset 1, 1

        CGPROGRAM
        #pragma vertex vert
        #pragma fragment frag
        #pragma multi_compile _ PIXELSNAP_ON
        #pragma shader_feature ETC1_EXTERNAL_ALPHA

        v2f vert(appdata_t IN)
        {
        	return vert_outline(IN);
        }

        fixed4 frag(v2f IN) : SV_Target
        {

           	fixed4 texColor = SampleSpriteTexture (IN.texcoord + fixed2(_MainTex_TexelSize.x* _OutlineSize,0)) * IN.color;
           	fixed4 c = _OutlineColor * texColor.a;
			        int w = ((int)(IN.texcoord.x * 100 + IN.texcoord.y * 100 + _Time.y * 5) & 1);
			        return c * w;
        }
        ENDCG
    }

    //outline right
    Pass
    {
   		Offset 1, 1

        CGPROGRAM
        #pragma vertex vert
        #pragma fragment frag
        #pragma multi_compile _ PIXELSNAP_ON
        #pragma shader_feature ETC1_EXTERNAL_ALPHA

        v2f vert(appdata_t IN)
        {
        	return vert_outline(IN);
        }

        fixed4 frag(v2f IN) : SV_Target
        {

           	fixed4 texColor = SampleSpriteTexture (IN.texcoord + fixed2(-_MainTex_TexelSize.x* _OutlineSize,0)) * IN.color;
           	fixed4 c = _OutlineColor * texColor.a;
			        int w = ((int)(IN.texcoord.x * 100 + IN.texcoord.y * 100 + _Time.y * 5) & 1);
			        return c * w;
        }
        ENDCG
    }

// Pass { Offset 0, 0

        CGPROGRAM
        #pragma vertex vert
        #pragma fragment frag
        #pragma multi_compile _ PIXELSNAP_ON
        #pragma shader_feature ETC1_EXTERNAL_ALPHA

        v2f vert(appdata_t IN)
        {
            v2f OUT;
            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;
        }


        fixed4 frag(v2f IN) : SV_Target
        {
            fixed4 c = SampleSpriteTexture (IN.texcoord) * IN.color;
            c.rgb *= c.a;
            return c;
        }
        ENDCG
    }
}

}