Shader "FullScreen/Ether"
{
    Properties
    {
        _SpectrumTexture("SpectrumTexture", 2D) = "white" {}
        _ThemeTexture("ThemeTexture", 2D) = "white" {}
        _SpectrumSize("SpectrumSize", float) = 16

        _Zoom("Zoom", range(-2, 2)) = 0.5
        _Wildness("Wildness", range(1, 10)) = 4.0
        _Brightness("Brightness", range(1, 10)) = 4.0
    }

    HLSLINCLUDE

    // HDRP stuff
    #pragma vertex Vert
    #pragma target 4.5
    #pragma only_renderers d3d11 playstation xboxone xboxseries vulkan metal switch
    #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/RenderPass/CustomPass/CustomPassCommon.hlsl"

    // here we go...
    sampler2D _SpectrumTexture;
    sampler2D _ThemeTexture;
    float _Zoom;
    float _Wildness;
    float _Brightness;

    // matrix fn
    float2x2 m(float a) {
        float c=cos(a), s=sin(a);
        float2x2 mat = { c, -s, s, c };
        return mat;
    }

    float map(float3 p, float4 spectrum) {
        float t = _Time.y * 0.2;
        p.xz = mul(m(t), p.xz);
        p.xy = mul(m(t), p.xy);
        float3 q = p*_Wildness;
        return length(p +
            float3(sin(t), sin(t), sin(t)))
                *log(length(p)+_Zoom) + sin(q.x+(q.z+sin(q.y))) * spectrum.x;
    }

    float4 FullScreenPass(Varyings varyings) : SV_Target {
        float depth = LoadCameraDepth(varyings.positionCS.xy);
        PositionInputs posInput = GetPositionInput(varyings.positionCS.xy, _ScreenSize.zw, depth, UNITY_MATRIX_I_VP, UNITY_MATRIX_V);

        // musique
        float sub = tex2D(_SpectrumTexture, 0.0);
        float bass = tex2D(_SpectrumTexture, 0.25);
        float mids = tex2D(_SpectrumTexture, 0.50);
        float highs = tex2D(_SpectrumTexture, 0.75);
        float4 spectrum = float4(sub, bass, mids, highs);

        // screen
        float2 p = posInput.positionNDC - .5;
        p.x *=  _ScreenParams.x / _ScreenParams.y;

        float t = _Time.y;

        // float3 colour = float3(0.0, 0.0, 0.0);
        float3 colour = float3(0.0, 0.0, 0.0);
        float damage = smoothstep(1.5, 3.5, highs);
        float iterations = 10.0;
        // float iterations = lerp(10.0, 50.0, highs);
        float str =  4.5; // lerp(4.9, 5.0, highs);
        float size = 1.0; //lerp(0.5, 2.0, mids);

        float3 theme = tex2D(_ThemeTexture, length(p)) * _Brightness;

        for(int i=0; i<=iterations; i++) {
            float3 n = float3(0.,0.,str) + normalize(float3(p, -size))*damage;
            float rz = map(n, spectrum);
            float f =  clamp((rz - map(n+.1, spectrum)), 0., 1.);
            float3 l = float3(0.01, 0.01, 0.01) * f + theme * f;
            colour = colour*l + smoothstep(2.5, .0, rz)*.7*l;
            damage += min(rz, 1.);
        }

        return float4(colour, 1.);
    }

    ENDHLSL

    SubShader
    {
        Tags{ "RenderPipeline" = "HDRenderPipeline" }
        Pass
        {
            Name "Custom Pass 0"

            ZWrite Off
            ZTest Always
            // Blend SrcAlpha OneMinusSrcAlpha
            Cull Off

            HLSLPROGRAM
                #pragma fragment FullScreenPass
            ENDHLSL
        }
    }
    Fallback Off
}