Sprite outline shader by Joyce

Outline.shader

Shader "Sprites/Outline"
{
    Properties
    {
        [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
        _Color ("Tint", Color) = (1,1,1,1)
        _Brightness("Outline Brightness", Range(0,8)) = 3.2
        _Width("Outline Width", Range(0,0.05)) = 0.003 
        _OutlineTex ("Outline Texture", 2D) = "white" {}
        _SpeedX("Scroll Speed X", Range(-20,20)) = 0.003   
        _SpeedY("Scroll Speed Y", Range(-20,20)) = 0.003   
        _OutlineColor("OutlineColor", Color) = (1,1,1,1)
        [MaterialToggle] JustOutline ("JustOutline", Float) = 0
        [MaterialToggle] TexturedOutline ("TexturedOutline", Float) = 0
        // stencil for (UI) Masking
        _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"
        }
        // stencil for (UI) Masking
         Stencil
        {
            Ref [_Stencil]
            Comp [_StencilComp]
            Pass [_StencilOp]
            ReadMask [_StencilReadMask]
            WriteMask [_StencilWriteMask]
        }
        Cull Off
        Lighting Off
        ZWrite Off
        Blend One OneMinusSrcAlpha
 
 
        Pass
        {
        CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma multi_compile _ JUSTOUTLINE_ON
            #pragma multi_compile _ TEXTUREDOUTLINE_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;
                float2 texcoord  : TEXCOORD0;
            };
           
           
            v2f vert(appdata_t IN)
            {
                v2f OUT;
                 UNITY_INITIALIZE_OUTPUT(v2f,OUT)
                OUT.vertex = UnityObjectToClipPos(IN.vertex);
                OUT.texcoord = IN.texcoord;
                return OUT;
            }
 
            fixed4 _Color;
            fixed4 _OutlineColor;
            sampler2D _MainTex;
            sampler2D _OutlineTex;
            float _Brightness;
            float _Width;
            float _SpeedX, _SpeedY;
 
            fixed4 frag(v2f IN) : SV_Target
            {              
                fixed4 c = tex2D(_MainTex, IN.texcoord) * _Color;
                fixed4 t = tex2D(_OutlineTex, float2(IN.texcoord.x + (_Time.x * _SpeedX), IN.texcoord.y + (_Time.x * _SpeedY))) * _Color;
                c.rgb *= c.a;
               
                // Move sprite in 4 directions according to width, we only care about the alpha
                float spriteLeft = tex2D(_MainTex, IN.texcoord + float2(_Width, 0)).a;
                float spriteRight = tex2D(_MainTex, IN.texcoord - float2(_Width,  0)).a;
                float spriteBottom = tex2D(_MainTex, IN.texcoord + float2( 0 ,_Width)).a;
                float spriteTop = tex2D(_MainTex, IN.texcoord - float2( 0 , _Width)).a;
               
                // then combine
                float result = (spriteRight + spriteLeft + spriteTop+ spriteBottom);
                // delete original alpha to only leave outline
                result *= (1-c.a);
                // add color and brightness
                float4 outlines = result * _OutlineColor* _Brightness;             
               
                #ifdef TEXTUREDOUTLINE_ON
                outlines *= t;
                #endif
                #ifdef JUSTOUTLINE_ON
                // only show outlines
                c = outlines;
                #else
                // show outlines +sprite
                c.rgb = c.rgb + outlines;
                #endif
               
                return  c ;
            }
        ENDCG
        }
    }
}