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

        _SphereSize("SphereSize", range(0, 3)) = 1
        _SphereStretch("SphereStretch", range(0, 3)) = 1
    }

    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 _SpectrumSize;

    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);
        float3 viewDirection = GetWorldSpaceNormalizeViewDir(posInput.positionWS);

        float2 ndc = posInput.positionNDC;
        float4 color = float4(0.0, 0.0, 0.0, 0.0);

        // convert to glsl mode and fix aspect ratio
        float2 uv = posInput.positionNDC - 0.5;
        uv.x *=  _ScreenParams.x / _ScreenParams.y;

        float time = _Time.y;

        // Background
        float4 outColour = float4(0.8+0.2*uv.y,0.8+0.2*uv.y,0.8+0.2*uv.y,1);

        // [unroll(100)]
        for(int i=0; i<40; i++) {
            // bubble seeds
            float pha =      sin(float(i)*546.13+1.0)*0.5 + 0.5;
            float siz = pow( sin(float(i)*651.74+5.0)*0.5 + 0.5, 4.0 );
            float pox =      sin(float(i)*321.55+4.1) * 1 / 1;

            // buble size, position and color
            float band = 1 / ((i % _SpectrumSize) + 1);
            float freq = tex2D(_SpectrumTexture, band);

            float rad = 0.1 + 0.1*freq;
            float2  pos = float2( pox, -1.0-rad + (2.0+2.0*rad)*fmod(pha+0.1*time*(0.2+0.8*siz),1.0));
            float dis = length( uv - pos );
            float3  col = lerp( float3(0.94,0.3,0.0), float3(0.1,0.4,0.8), 0.5+0.5*sin(float(i)*1.2+1.9));
            col+= 8.0*smoothstep( rad*0.95, rad, dis );

            // render
            float f = length(uv-pos)/rad;
            f = sqrt(clamp(1.0-f*f,0.0,1.0));
            outColour -= float4(col.zyx *(1.0-smoothstep( rad*0.95, rad, dis )) * f, 0.0);
        }

        // Vignetting
        // outColour *= sqrt(1.5-0.5*length(uv));

        return outColour;
    }

    ENDHLSL

    SubShader
    {
        Tags{ "RenderPipeline" = "HDRenderPipeline" }
        Pass
        {
            Name "GeneDrive"

            ZWrite Off
            ZTest Always
            // Blend SrcAlpha OneMinusSrcAlpha
            Cull Off

            HLSLPROGRAM
                #pragma fragment FullScreenPass
            ENDHLSL
        }
    }
    Fallback Off
}