Unity Sprites/Cheap Outer Glow Shader

    Shader "Sprites/Cheap Outer Glow"

    {
        Properties

        {
            [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
            _Color ("Tint", Color) = (1,1,1,1)
            _GlowScale ("Glow Scale", Range(0,1)) = 1
            _GlowColor ("Glow Color", Color) = (1,1,1,1)
            [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 target 2.0
                #pragma multi_compile _ PIXELSNAP_ON
                #pragma multi_compile _ ETC1_EXTERNAL_ALPHA
                #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(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;
    
                fixed _GlowScale;
                fixed4 _GlowColor;
    
                fixed4 SampleSpriteTexture (float2 uv)
                {
                    fixed4 color = tex2D (_MainTex, uv);
    
    #if ETC1_EXTERNAL_ALPHA
 // get the color from an external texture (usecase: Alpha support for ETC1 on android)
               

               color.a = tex2D (_AlphaTex, uv).r ;

    #endif

//ETC1_EXTERNAL_ALPHA
    
                    return color;
                }
    
                fixed4 frag(v2f IN) : SV_Target
                {
                    fixed4 c = SampleSpriteTexture (IN.texcoord) * IN.color;
    
                    // Use alpha assuming glow is a gradient from 0.0 to ~0.75% alpha, and the rest is the sprite.
             

                    fixed spriteAlpha = saturate(c.a * 4.0 - 3.0);
                    fixed glowAlpha = saturate(1.0 - (1.0 - c.a / 0.75) / max(_GlowScale, 0.01)) * saturate(_GlowScale * 32.0);
                   

                    c.a = max(spriteAlpha, glowAlpha * _GlowColor.a);

                    c.rgb = lerp(_GlowColor.rgb, c.rgb, 1.0 - (1.0 - saturate(spriteAlpha / max(_GlowColor.a, 0.01))) * saturate(_GlowScale * 32.0));
    
                    c.rgb *= c.a;
                    return c;
                }
            ENDCG
            }
        }
    }