Shader "Kaiju/Bubbles"
{
    HLSLINCLUDE

    #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"

    // The PositionInputs struct allow you to retrieve a lot of useful information for your fullScreenShader:
    // struct PositionInputs
    // {
    //     float3 positionWS;  // World space position (could be camera-relative)
    //     float2 positionNDC; // Normalized screen coordinates within the viewport    : [0, 1) (with the half-pixel offset)
    //     uint2  positionSS;  // Screen space pixel coordinates                       : [0, NumPixels)
    //     uint2  tileCoord;   // Screen tile coordinates                              : [0, NumTiles)
    //     float  deviceDepth; // Depth from the depth buffer                          : [0, 1] (typically reversed)
    //     float  linearDepth; // View space Z coordinate                              : [Near, Far]
    // };

    // To sample custom buffers, you have access to these functions:
    // But be careful, on most platforms you can't sample to the bound color buffer. It means that you
    // can't use the SampleCustomColor when the pass color buffer is set to custom (and same for camera the buffer).
    // float4 SampleCustomColor(float2 uv);
    // float4 LoadCustomColor(uint2 pixelCoords);
    // float LoadCustomDepth(uint2 pixelCoords);
    // float SampleCustomDepth(float2 uv);

    // There are also a lot of utility function you can use inside Common.hlsl and Color.hlsl,
    // you can check them out in the source code of the core SRP package.

    float4 FullScreenPass(Varyings varyings) : SV_Target
    {
        UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(varyings);
        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);
        float4 color = float4(0.0, 0.0, 0.0, 0.0);

        // Load the camera color buffer at the mip 0 if we're not at the before rendering injection point
        if (_CustomPassInjectionPoint != CUSTOMPASSINJECTIONPOINT_BEFORE_RENDERING)
            color = float4(CustomPassLoadCameraColor(varyings.positionCS.xy, 0), 1);


        // get uv
        float2 uv = posInput.positionNDC;
        // fix aspect ratio
        uv.x *=  _ScreenParams.x / _ScreenParams.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 rad = 0.1 + 0.5*siz;
            float2  pos = float2( pox, -1.0-rad + (2.0+2.0*rad)*fmod(pha+0.1*_Time.y*(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 "Custom Pass 0"

            ZWrite Off
            ZTest Always
            Blend SrcAlpha OneMinusSrcAlpha
            Cull Off

            HLSLPROGRAM
                #pragma fragment FullScreenPass
            ENDHLSL
        }
    }
    Fallback Off
}