/*************************************************************************/
/*                  License Terms for ACES Components                    */
/*                                                                       */
/*  ACES software and tools are provided by the Academy under the        */
/*  following terms and conditions: A worldwide, royalty-free,           */
/*  non-exclusive right to copy, modify, create derivatives, and         */
/*  use, in source and binary forms, is hereby granted, subject to       */
/*  acceptance of this license. Performance of any of the                */
/*  aforementioned acts indicates acceptance to be bound by the          */
/*  following terms and conditions:                                      */
/*                                                                       */
/*  Copyright © 2014 Academy of Motion Picture Arts and Sciences         */
/*  (A.M.P.A.S.). Portions contributed by others as indicated.           */
/*  All rights reserved.                                                 */
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/*  above copyright notice, this list of conditions and the              */
/*  Disclaimer of Warranty.                                              */
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/*  this list of conditions and the Disclaimer of Warranty in            */
/*  the documentation and/or other materials provided with the           */
/*  distribution.                                                        */
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/*  to trademarks, copyrights, patents, trade secrets or any other       */
/*  intellectual property of A.M.P.A.S. or any contributors, except      */
/*  as expressly stated herein.                                          */
/*  Neither the name “A.M.P.A.S.” nor the name of any other              */
/*  contributors to this software may be used to endorse or promote      */
/*  products derivative of or based on this software without express     */
/*  prior written permission of A.M.P.A.S. or the contributors, as       */
/*  appropriate.                                                         */
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/*  of California, and any disputes related thereto shall be subject     */
/*  to the jurisdiction of the courts therein.                           */
/*                                                                       */
/*  Disclaimer of Warranty: THIS SOFTWARE IS PROVIDED BY A.M.P.A.S.      */
/*  AND CONTRIBUTORS “AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES,      */
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/*  DAMAGE.                                                              */
/*                                                                       */
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/*  WHETHER DISCLOSED OR UNDISCLOSED.                                    */
/*************************************************************************/

float YTolinearCV(float y, float maxY, float minY) {
    return (y - minY) / (maxY - minY);
}

vec3 darkSurroundToDimSurround(vec3 linearCV) {
    vec3 xyY = xyzToXyV(linearCV * AP1_2_XYZ_MAT);
    xyY.b    = pow(clamp01(xyY.b), DIM_SURROUND_GAMMA);
    return xyYToXYZ(xyY) * XYZ_2_AP1_MAT;
}

float moncurve_r(float y, float gamma, float offset) {
    float yb = pow(offset * gamma / (( gamma - 1.0) * (1.0 + offset)), gamma);
    float rs = pow((gamma - 1.0) / offset, gamma - 1.0) * pow((1.0 + offset) / gamma, gamma);

    if(y >= yb) return (1.0 + offset) * pow(y, 1.0 / gamma) - offset;
    else        return y * rs;
}

void odt(inout vec3 color) {
    // Apply the tonescale independently in rendering-space RGB
    color.r = segmentedSplineC9Fwd(color.r);
    color.g = segmentedSplineC9Fwd(color.g);
    color.b = segmentedSplineC9Fwd(color.b);

    // Scale luminance to linear code value
    color.r = YTolinearCV(color.r, ODT_CINEMA_WHITE, ODT_CINEMA_BLACK);
    color.g = YTolinearCV(color.g, ODT_CINEMA_WHITE, ODT_CINEMA_BLACK);
    color.b = YTolinearCV(color.b, ODT_CINEMA_WHITE, ODT_CINEMA_BLACK);

    color  = darkSurroundToDimSurround(color);               // Apply gamma adjustment to compensate for dim surround
    color *= calcSatAdjustMatrix(ODT_SAT_FACTOR, AP1_RGB2Y); // Apply desaturation to compensate for luminance difference

    color *= AP1_2_XYZ_MAT; // Rendering space RGB to XYZ
    color *= D60_2_D65_CAT; // Apply CAT from ACES white point to assumed observer adapted white point

    // CIE XYZ to display primaries and handling out-of-gamut values
    color = clamp01(color * XYZ_2_SRGB_MAT);

    // Gamma curve to convert back to monitor RGB
    color.r = moncurve_r(color.r, ODT_DISPGAMMA, ODT_GAMMA_OFFSET);
    color.g = moncurve_r(color.g, ODT_DISPGAMMA, ODT_GAMMA_OFFSET);
    color.b = moncurve_r(color.b, ODT_DISPGAMMA, ODT_GAMMA_OFFSET);
}
