SpriteOutline.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
		}
	}
}