Shader "UI/Glowy Dissolve"
{
    Properties
    {
        [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
        _Color ("Tint", Color) = (1,1,1,1)

        _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
        [Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip ("Use Alpha Clip", Float) = 0

        _DissolveAmount ("Dissolve Amount", Range(0, 1)) = 1
        _Direction ("Direction", Range(0, 1)) = 0
        [HDR] _DissolveColor ("Dissolve Color", Color) = (2,0,6,1)
        _DissolveColorOpacity ("Dissolve Color Opacity", Range(0, 1)) = 0.8
        _EdgeWidth ("Edge Width", Range(0.001, 0.5)) = 0.08
        _BlockCountX ("Block Count X", Range(1, 256)) = 40
        _BlockCountY ("Block Count Y", Range(1, 256)) = 14
        _GlowIntensity ("Glow Intensity", Range(0, 8)) = 1.5
        _GlitchJitter ("Glitch Jitter", Range(0, 0.5)) = 0.12
        _GlitchStripeIntensity ("Glitch Stripe Intensity", Range(0, 1)) = 0.2
        _GlitchRgbSplit ("Glitch RGB Split", Range(0, 0.1)) = 0.015
    }

    SubShader
    {
        Tags
        {
            "Queue"="Transparent"
            "IgnoreProjector"="True"
            "RenderType"="Transparent"
            "PreviewType"="Plane"
            "CanUseSpriteAtlas"="True"
        }

        Stencil
        {
            Ref [_Stencil]
            ReadMask [_StencilReadMask]
            WriteMask [_StencilWriteMask]
            Comp [_StencilComp]
            Pass [_StencilOp]
        }

        Cull Off
        Lighting Off
        ZWrite Off
        ZTest [unity_GUIZTestMode]
        Blend One OneMinusSrcAlpha
        ColorMask [_ColorMask]

        Pass
        {
            Name "Default"
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma target 3.0

            #include "UnityCG.cginc"
            #include "UnityUI.cginc"

            #pragma multi_compile_local _ UNITY_UI_CLIP_RECT
            #pragma multi_compile_local _ UNITY_UI_ALPHACLIP

            struct appdata_t
            {
                float4 vertex   : POSITION;
                float4 color    : COLOR;
                float2 texcoord : TEXCOORD0;
                UNITY_VERTEX_INPUT_INSTANCE_ID
            };

            struct v2f
            {
                float4 vertex        : SV_POSITION;
                fixed4 color         : COLOR;
                float2 texcoord      : TEXCOORD0;
                float4 worldPosition : TEXCOORD1;
                float4 mask          : TEXCOORD2;
                float2 localPos      : TEXCOORD3;
                UNITY_VERTEX_OUTPUT_STEREO
            };

            sampler2D _MainTex;
            fixed4 _Color;
            fixed4 _TextureSampleAdd;
            float4 _ClipRect;
            float4 _MainTex_ST;
            float _UIMaskSoftnessX;
            float _UIMaskSoftnessY;

            float _DissolveAmount;
            float _Direction;
            float4 _DissolveColor;
            float _DissolveColorOpacity;
            float _EdgeWidth;
            float _BlockCountX;
            float _BlockCountY;
            float _GlowIntensity;
            float _GlitchJitter;
            float _GlitchStripeIntensity;
            float _GlitchRgbSplit;

            float Hash21(float2 p)
            {
                p = frac(p * float2(123.34, 345.45));
                p += dot(p, p + 34.345);
                return frac(p.x * p.y);
            }

            float Noise2D(float2 uv)
            {
                float2 i = floor(uv);
                float2 f = frac(uv);

                float a = Hash21(i);
                float b = Hash21(i + float2(1, 0));
                float c = Hash21(i + float2(0, 1));
                float d = Hash21(i + float2(1, 1));

                float2 u = f * f * (3.0 - 2.0 * f);
                return lerp(lerp(a, b, u.x), lerp(c, d, u.x), u.y);
            }

            v2f vert(appdata_t v)
            {
                v2f OUT;
                UNITY_SETUP_INSTANCE_ID(v);
                UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);

                float4 vPosition = UnityObjectToClipPos(v.vertex);
                OUT.worldPosition = v.vertex;
                OUT.vertex = vPosition;
                OUT.texcoord = TRANSFORM_TEX(v.texcoord, _MainTex);
                OUT.localPos = v.vertex.xy;

                float2 pixelSize = vPosition.w;
                pixelSize /= float2(1, 1) * abs(mul((float2x2)UNITY_MATRIX_P, _ScreenParams.xy));

                float4 clampedRect = clamp(_ClipRect, -2e10, 2e10);
                OUT.mask = float4(
                    v.vertex.xy * 2 - clampedRect.xy - clampedRect.zw,
                    0.25 / (0.25 * half2(_UIMaskSoftnessX, _UIMaskSoftnessY) + abs(pixelSize.xy))
                );

                OUT.color = v.color * _Color;
                return OUT;
            }

            fixed4 frag(v2f IN) : SV_Target
            {
                float dir = step(0.5, _Direction);
                float2 directedUv = float2(lerp(IN.texcoord.x, 1.0 - IN.texcoord.x, dir), IN.texcoord.y);

                float2 blockCoord = floor(directedUv * float2(max(1.0, _BlockCountX), max(1.0, _BlockCountY)));
                float blockNoise = Hash21(blockCoord);
                float rowNoise = Hash21(float2(floor(directedUv.y * max(1.0, _BlockCountY)), floor(_DissolveAmount * 64.0)));
                float stripeNoise = Hash21(float2(floor(directedUv.y * max(2.0, _BlockCountY * 0.5)), 17.0));

                float front = saturate(_DissolveAmount + (blockNoise - 0.5) * _GlitchJitter);
                float bandWidth = max(_EdgeWidth, 0.001);
                float edgeBand = saturate(1.0 - abs(directedUv.x - front) / bandWidth);

                float stripeOffset = (stripeNoise - 0.5) * _GlitchStripeIntensity * edgeBand;
                float2 glitchOffset = float2(((rowNoise - 0.5) * _GlitchJitter * 0.35 + stripeOffset) * edgeBand, 0.0);
                float2 sampleUv = IN.texcoord + glitchOffset;

                fixed4 baseTex;
                baseTex.r = tex2D(_MainTex, sampleUv + float2(_GlitchRgbSplit * edgeBand, 0)).r;
                baseTex.g = tex2D(_MainTex, sampleUv).g;
                baseTex.b = tex2D(_MainTex, sampleUv - float2(_GlitchRgbSplit * edgeBand, 0)).b;
                baseTex.a = tex2D(_MainTex, sampleUv).a;
                baseTex += _TextureSampleAdd;
                fixed4 color = baseTex * IN.color;

                float visible = step(directedUv.x, front);
                float edge = smoothstep(front - bandWidth, front, directedUv.x) * visible;
                float glowMask = edge * _DissolveColorOpacity;

                color.a *= visible;
                color.rgb = lerp(color.rgb, _DissolveColor.rgb * _GlowIntensity, glowMask);

                #ifdef UNITY_UI_CLIP_RECT
                half2 m = saturate((_ClipRect.zw - _ClipRect.xy - abs(IN.mask.xy)) * IN.mask.zw);
                color.a *= m.x * m.y;
                #endif

                #ifdef UNITY_UI_ALPHACLIP
                clip(color.a - 0.001);
                #endif

                color.rgb *= color.a;
                return color;
            }
            ENDCG
        }
    }
}