Shader "Sprites/Filters"
{
    Properties
    {
        [NoScaleOffset]_MainTex ("Main texture", 2D) = "white" {}
        [KeywordEnum(Edges_Transparency, Edges)] _Mode("Mode", Float) = 0
        _Intensity ("", Range(1,20)) = 0
    }
    SubShader
    {

        Pass
        {
            Blend One OneMinusSrcAlpha

            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"
            #pragma multi_compile _MODE_EDGES_TRANSPARENCY _MODE_EDGES


            #define MAX_INTENSITY 20
            #define PIXELATED_MULTIPLIER 20

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
                float4 color : COLOR;
            };

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
                float4 color : COLOR;
            };

            sampler2D _MainTex;
            float4 _MainTex_TexelSize;

            float _Intensity;

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                o.color = v.color;
                return o;
            }

            //filters

            float4 edgeDetectionTransparent(v2f i)
            {
                float4 col = tex2D(_MainTex, i.uv);
                float4 col2 = tex2D(_MainTex, float2(i.uv.x - _MainTex_TexelSize.x,i.uv.y - _MainTex_TexelSize.y));

                float4 finalCol = float4((col - col2).rgb * _Intensity, col.a);
                finalCol.a = (finalCol.r + finalCol.g + finalCol.b)/3.0f * col.a;
                return finalCol;
            }

            float4 edgeDetection(v2f i)
            {
                float4 col = tex2D(_MainTex, i.uv);
                float4 col2 = tex2D(_MainTex, float2(i.uv.x - _MainTex_TexelSize.x,i.uv.y - _MainTex_TexelSize.y));

                float4 finalCol = float4((col - col2).rgb * _Intensity, col.a);
                return finalCol;
            }

            float4 inverseEdgeDetection(v2f i)
            {
                float4 col = tex2D(_MainTex, i.uv);
                float4 col2 = tex2D(_MainTex, float2(i.uv.x - _MainTex_TexelSize.x,i.uv.y - _MainTex_TexelSize.y));
                float4 finalCol = float4((col - col2).rgb * _Intensity, col.a);

                float par = 1 - finalCol.r;
                col.rgb *= par;
                //finalCol = float4(col.rgb - finalCol.rgb, col.a);
                //finalCol.a = (finalCol.r + finalCol.g + finalCol.b)/3.0f * col.a;
                return col;
            }

            float4 emboss(v2f i)
            {
                float4 col = tex2D(_MainTex, i.uv);
                float4 finalCol = tex2D(_MainTex, i.uv) + tex2D(_MainTex, float2(i.uv.x + _MainTex_TexelSize.x, i.uv.y + _MainTex_TexelSize.y)) +
                    tex2D(_MainTex, float2(i.uv.x + _MainTex_TexelSize.x, i.uv.y)) + tex2D(_MainTex, float2(i.uv.x, i.uv.y + _MainTex_TexelSize.y))
                    - tex2D(_MainTex, float2(i.uv.x - _MainTex_TexelSize.x, i.uv.y)) - tex2D(_MainTex, float2(i.uv.x, i.uv.y - _MainTex_TexelSize.y))
                    - tex2D(_MainTex, float2(i.uv.x - _MainTex_TexelSize.x, i.uv.y - _MainTex_TexelSize.y));

                finalCol = float4(finalCol.rgb * _Intensity, col.a);

                return finalCol;
            }
            /*
            fixed4 laplacianFilter(v2f i)
            {
                fixed4 col = tex2D(_MainTex, i.uv) * 8;
                fixed4 substract = -(tex2D(_MainTex, float2(i.uv.x + _MainTex_TexelSize.x, i.uv.y)) + tex2D(_MainTex, float2(i.uv.x - _MainTex_TexelSize.x, i.uv.y))
                    + tex2D(_MainTex, float2(i.uv.x + _MainTex_TexelSize.x, i.uv.y - _MainTex_TexelSize.y)) + tex2D(_MainTex, float2(i.uv.x - _MainTex_TexelSize.x, i.uv.y - _MainTex_TexelSize.y))
                    + tex2D(_MainTex, float2(i.uv.x + _MainTex_TexelSize.x, i.uv.y + _MainTex_TexelSize.y)) + tex2D(_MainTex, float2(i.uv.x - _MainTex_TexelSize.x, i.uv.y + _MainTex_TexelSize.y))
                    + tex2D(_MainTex, float2(i.uv.x, i.uv.y + _MainTex_TexelSize.y)) + tex2D(_MainTex, float2(i.uv.x, i.uv.y - _MainTex_TexelSize.y)));

                col = col + substract;
                col *= _Intensity;
                col.a = 1;
                return col;

            }*/

            float4 blur(v2f i)
            {
                return float4(0,0,0,0);
            }

            float4 luminance(float4 color)
            {
                float lum = 0.299*color.r + 0.587*color.g + 0.114*color.b;
                return float4(lum,lum,lum, color.a);
            }

            // filters

            // additional
            float4 colorLerp(float4 col1, float4 col2, float val)
            {
                return col1 * (1 - val) + col2 * val;
            }

            float lerp(float min, float max, float cur) // cur = [0,1]
            {
                return min  + (max-min) * cur;
            }
            // additional

            float4 frag (v2f i) : SV_Target
            {
                // sample the texture
                float4 spriteColor = tex2D(_MainTex, i.uv);
                float4 col = spriteColor;

                #if EDGES_TRANSPARENCY
                    col = edgeDetectionTransparent(i);
                    float maxChannel = max(col.r, max(col.g, col.b));
                    col.rgb = float3(maxChannel,maxChannel, maxChannel);
                #endif

                #if EDGES
                    col = edgeDetection(i);
                    float maxChannel = max(col.r, max(col.g, col.b));
                    col.rgb = float3(maxChannel,maxChannel, maxChannel);
                #endif

                /*else if(_Filter == 2) // EDGES
                {

                }
                else if(_Filter == 3)
                {
                    col = emboss(i);
                    //col.rgb *= spriteColor.a;
                }
                else if(_Filter == 4)
                {
                    col = inverseEdgeDetection(i);
                    //col.rgb *= spriteColor.a;
                }
                else if(_Filter == 5) // BLACK_WHITE
                {
                    col = colorLerp(col, luminance(col), _Intensity/ MAX_INTENSITY);
                }
                else if(_Filter == 6) // PIXELATED
                {
                    float pixelU = lerp(_MainTex_TexelSize.x,_MainTex_TexelSize.x * PIXELATED_MULTIPLIER,
                        _Intensity/MAX_INTENSITY);
                    float pixelV = lerp(_MainTex_TexelSize.y,_MainTex_TexelSize.y * PIXELATED_MULTIPLIER,
                        _Intensity/MAX_INTENSITY);

                    float2 uv = float2((int)(i.uv.x / pixelU) * pixelU,
                        (int)(i.uv.y / pixelV) * pixelV);

                    col = tex2D(_MainTex, uv);
                }
                else if(_Filter == 7)
                {

                }
                    */

                col *= i.color;
                col.rgb *= col.a;

                return col;
            }
            ENDCG
        }
    }
}