// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

Shader "MiniMapEffect/MapOutline"
{
    Properties
    {
        _MainTex ("Sprite Texture", 2D) = "white" {}
        _Color ("Tint", Color) = (1,1,1,1)
        PixelSnap ("Pixel snap", Float) = 1

        // Add values to determine if outlining is enabled and outline color.
        _Outline ("Outline", Float) = 1
        _OutlineColor("Outline Color", Color) = (1,1,1,1)
        _TexelSizeX ("TexelSizeX", Float) = 1
        _TexelSizeY ("TexelSizeY", Float) = 1
    }

    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 multi_compile _ PIXELSNAP_ON
            #pragma shader_feature 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;
            float _Outline;
            fixed4 _OutlineColor;
            //fixed4 _MainTex_TexelSize;
            float _TexelSizeX;
            float _TexelSizeY;

            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;
            

            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;

                // If outline is enabled and there is a pixel, try to draw an outline.
                if (_Outline > 0 && c.a != 0) {
                    // Get the neighbouring four pixels.
                    fixed4 pixelUp = tex2D(_MainTex, IN.texcoord + fixed2(0, _TexelSizeY));
                    fixed4 pixelDown = tex2D(_MainTex, IN.texcoord - fixed2(0, _TexelSizeY));
                    fixed4 pixelRight = tex2D(_MainTex, IN.texcoord + fixed2(_TexelSizeX, 0));
                    fixed4 pixelLeft = tex2D(_MainTex, IN.texcoord - fixed2(_TexelSizeX, 0));

                    // && 
                    // pixelDown.rgba == fixed4(0, 0, 0, 1) && 
                    // pixelRight.rgba == fixed4(0, 0, 0, 1) &&
                    // pixelLeft.rgba == fixed4(0, 0, 0, 1)
                    if (pixelUp.r == pixelDown.r == pixelRight.r == pixelLeft.r) {
                        pixelUp.a = 0;
                    }
                    // If one of the neighbouring pixels is invisible, we render an outline.
                    if (pixelUp.a * pixelDown.a * pixelRight.a * pixelLeft.a == 0) {
                        c.rgba = fixed4(1, 1, 1, 0.5f) * _OutlineColor;
                    }
                }

                c.rgb *= c.a;

                return c;
            }
            ENDCG
        }
    }
}