/*
 * Copyright (c) Contributors to the Open 3D Engine Project.
 * For complete copyright and license terms please see the LICENSE at the root of this distribution.
 *
 * SPDX-License-Identifier: Apache-2.0 OR MIT
 *
 */

//
// ACES implementation
// This implementation is partially ported from NVIDIA HDR sample.
// https://developer.nvidia.com/high-dynamic-range-display-development
//

#include <Atom/Features/SrgSemantics.azsli>

#include <Atom/Features/PostProcessing/FullscreenPixelInfo.azsli>
#include <Atom/Features/PostProcessing/FullscreenVertex.azsli>
#include <Atom/Features/PostProcessing/PostProcessUtil.azsli>
#include <Atom/Features/PostProcessing/Aces.azsli>

////////////////////////////////////////////////////////////////////////////////

ShaderResourceGroup PassSrg : SRG_PerPass
{
    Texture2D<float4> m_framebuffer;
    Sampler LinearSampler
    {
        MinFilter = Linear;
        MagFilter = Linear;
        MipFilter = Linear;
        AddressU = Clamp;
        AddressV = Clamp;
        AddressW = Clamp;
    };

    // ACES spline parameters
    SegmentedSplineParamsC9 m_acesSplineParams;
    // Color transformation matrix from XYZ to the display's color primaries
    row_major float3x3 m_XYZtoDisplayPrimaries;
    // Reference white and black luminance values
    float2 m_cinemaLimits;
    // Bit flag for control the ODT shader behavior
    int m_outputDisplayTransformFlags;
    // The ODT output mode
    int m_outputDisplayTransformMode;
    // Gamma adjustment to be applied to compensate for the condition of the viewing environment.
    // Note that ACES uses a value of 0.9811 for adjusting from dark to dim surrounding.
    float m_surroundGamma;
    // Optional gamma value that is applied as basic gamma curve OETF
    float m_gamma;
}

////////////////////////////////////////////////////////////////////////////////
// A entry point of pixel shader.
PSOutput MainPS(VSOutput IN)
{
    PSOutput OUT;

    OutputTransformParameters outputTransformParams;
    outputTransformParams.outputDisplayTransformFlags = PassSrg::m_outputDisplayTransformFlags;
    outputTransformParams.outputDisplayTransformMode = PassSrg::m_outputDisplayTransformMode;
    outputTransformParams.cinemaLimits = PassSrg::m_cinemaLimits;
    outputTransformParams.acesSplineParams = PassSrg::m_acesSplineParams;
    outputTransformParams.XYZtoDisplayPrimaries = PassSrg::m_XYZtoDisplayPrimaries;
    outputTransformParams.surroundGamma = PassSrg::m_surroundGamma;
    outputTransformParams.gamma = PassSrg::m_gamma;

    float3 color = PassSrg::m_framebuffer.Sample(PassSrg::LinearSampler, IN.m_texCoord).rgb;

    // Convert to ACEScg to ACES color space
    float3 aces = mul(AP1ToAP0Mat, color.rgb);

    float3 oces = ReferenceRenderingTransform(aces);
    OUT.m_color.rgb = OutputDeviceTransform(oces, outputTransformParams);
    OUT.m_color.w = 1;

    return OUT;
}