/*
 * Copyright (C) 2022 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.internal.graphics.cam;

/**
 * An efficient algorithm for determining the closest sRGB color to a set of HCT coordinates,
 * based on geometrical insights for finding intersections in linear RGB, CAM16, and L*a*b*.
 *
 * Algorithm identified and implemented by Tianguang Zhang.
 * Copied from //java/com/google/ux/material/libmonet/hct on May 22 2022.
 * ColorUtils/MathUtils functions that were required were added to CamUtils.
 */
public class HctSolver {
    private HctSolver() {}

    // Matrix used when converting from linear RGB to CAM16.
    static final double[][] SCALED_DISCOUNT_FROM_LINRGB =
            new double[][] {
                    new double[] {
                            0.001200833568784504, 0.002389694492170889, 0.0002795742885861124,
                    },
                    new double[] {
                            0.0005891086651375999, 0.0029785502573438758, 0.0003270666104008398,
                    },
                    new double[] {
                            0.00010146692491640572, 0.0005364214359186694, 0.0032979401770712076,
                    },
            };

    // Matrix used when converting from CAM16 to linear RGB.
    static final double[][] LINRGB_FROM_SCALED_DISCOUNT =
            new double[][] {
                    new double[] {
                            1373.2198709594231, -1100.4251190754821, -7.278681089101213,
                    },
                    new double[] {
                            -271.815969077903, 559.6580465940733, -32.46047482791194,
                    },
                    new double[] {
                            1.9622899599665666, -57.173814538844006, 308.7233197812385,
                    },
            };

    // Weights for transforming a set of linear RGB coordinates to Y in XYZ.
    static final double[] Y_FROM_LINRGB = new double[] {0.2126, 0.7152, 0.0722};

    // Lookup table for plane in XYZ's Y axis (relative luminance) that corresponds to a given
    // L* in L*a*b*. HCT's T is L*, and XYZ's Y is directly correlated to linear RGB, this table
    // allows us to thus find the intersection between HCT and RGB, giving a solution to the
    // RGB coordinates that correspond to a given set of HCT coordinates.
    static final double[] CRITICAL_PLANES =
            new double[] {
                    0.015176349177441876,
                    0.045529047532325624,
                    0.07588174588720938,
                    0.10623444424209313,
                    0.13658714259697685,
                    0.16693984095186062,
                    0.19729253930674434,
                    0.2276452376616281,
                    0.2579979360165119,
                    0.28835063437139563,
                    0.3188300904430532,
                    0.350925934958123,
                    0.3848314933096426,
                    0.42057480301049466,
                    0.458183274052838,
                    0.4976837250274023,
                    0.5391024159806381,
                    0.5824650784040898,
                    0.6277969426914107,
                    0.6751227633498623,
                    0.7244668422128921,
                    0.775853049866786,
                    0.829304845476233,
                    0.8848452951698498,
                    0.942497089126609,
                    1.0022825574869039,
                    1.0642236851973577,
                    1.1283421258858297,
                    1.1946592148522128,
                    1.2631959812511864,
                    1.3339731595349034,
                    1.407011200216447,
                    1.4823302800086415,
                    1.5599503113873272,
                    1.6398909516233677,
                    1.7221716113234105,
                    1.8068114625156377,
                    1.8938294463134073,
                    1.9832442801866852,
                    2.075074464868551,
                    2.1693382909216234,
                    2.2660538449872063,
                    2.36523901573795,
                    2.4669114995532007,
                    2.5710888059345764,
                    2.6777882626779785,
                    2.7870270208169257,
                    2.898822059350997,
                    3.0131901897720907,
                    3.1301480604002863,
                    3.2497121605402226,
                    3.3718988244681087,
                    3.4967242352587946,
                    3.624204428461639,
                    3.754355295633311,
                    3.887192587735158,
                    4.022731918402185,
                    4.160988767090289,
                    4.301978482107941,
                    4.445716283538092,
                    4.592217266055746,
                    4.741496401646282,
                    4.893568542229298,
                    5.048448422192488,
                    5.20615066083972,
                    5.3666897647573375,
                    5.5300801301023865,
                    5.696336044816294,
                    5.865471690767354,
                    6.037501145825082,
                    6.212438385869475,
                    6.390297286737924,
                    6.571091626112461,
                    6.7548350853498045,
                    6.941541251256611,
                    7.131223617812143,
                    7.323895587840543,
                    7.5195704746346665,
                    7.7182615035334345,
                    7.919981813454504,
                    8.124744458384042,
                    8.332562408825165,
                    8.543448553206703,
                    8.757415699253682,
                    8.974476575321063,
                    9.194643831691977,
                    9.417930041841839,
                    9.644347703669503,
                    9.873909240696694,
                    10.106627003236781,
                    10.342513269534024,
                    10.58158024687427,
                    10.8238400726681,
                    11.069304815507364,
                    11.317986476196008,
                    11.569896988756009,
                    11.825048221409341,
                    12.083451977536606,
                    12.345119996613247,
                    12.610063955123938,
                    12.878295467455942,
                    13.149826086772048,
                    13.42466730586372,
                    13.702830557985108,
                    13.984327217668513,
                    14.269168601521828,
                    14.55736596900856,
                    14.848930523210871,
                    15.143873411576273,
                    15.44220572664832,
                    15.743938506781891,
                    16.04908273684337,
                    16.35764934889634,
                    16.66964922287304,
                    16.985093187232053,
                    17.30399201960269,
                    17.62635644741625,
                    17.95219714852476,
                    18.281524751807332,
                    18.614349837764564,
                    18.95068293910138,
                    19.290534541298456,
                    19.633915083172692,
                    19.98083495742689,
                    20.331304511189067,
                    20.685334046541502,
                    21.042933821039977,
                    21.404114048223256,
                    21.76888489811322,
                    22.137256497705877,
                    22.50923893145328,
                    22.884842241736916,
                    23.264076429332462,
                    23.6469514538663,
                    24.033477234264016,
                    24.42366364919083,
                    24.817520537484558,
                    25.21505769858089,
                    25.61628489293138,
                    26.021211842414342,
                    26.429848230738664,
                    26.842203703840827,
                    27.258287870275353,
                    27.678110301598522,
                    28.10168053274597,
                    28.529008062403893,
                    28.96010235337422,
                    29.39497283293396,
                    29.83362889318845,
                    30.276079891419332,
                    30.722335150426627,
                    31.172403958865512,
                    31.62629557157785,
                    32.08401920991837,
                    32.54558406207592,
                    33.010999283389665,
                    33.4802739966603,
                    33.953417292456834,
                    34.430438229418264,
                    34.911345834551085,
                    35.39614910352207,
                    35.88485700094671,
                    36.37747846067349,
                    36.87402238606382,
                    37.37449765026789,
                    37.87891309649659,
                    38.38727753828926,
                    38.89959975977785,
                    39.41588851594697,
                    39.93615253289054,
                    40.460400508064545,
                    40.98864111053629,
                    41.520882981230194,
                    42.05713473317016,
                    42.597404951718396,
                    43.141702194811224,
                    43.6900349931913,
                    44.24241185063697,
                    44.798841244188324,
                    45.35933162437017,
                    45.92389141541209,
                    46.49252901546552,
                    47.065252796817916,
                    47.64207110610409,
                    48.22299226451468,
                    48.808024568002054,
                    49.3971762874833,
                    49.9904556690408,
                    50.587870934119984,
                    51.189430279724725,
                    51.79514187861014,
                    52.40501387947288,
                    53.0190544071392,
                    53.637271562750364,
                    54.259673423945976,
                    54.88626804504493,
                    55.517063457223934,
                    56.15206766869424,
                    56.79128866487574,
                    57.43473440856916,
                    58.08241284012621,
                    58.734331877617365,
                    59.39049941699807,
                    60.05092333227251,
                    60.715611475655585,
                    61.38457167773311,
                    62.057811747619894,
                    62.7353394731159,
                    63.417162620860914,
                    64.10328893648692,
                    64.79372614476921,
                    65.48848194977529,
                    66.18756403501224,
                    66.89098006357258,
                    67.59873767827808,
                    68.31084450182222,
                    69.02730813691093,
                    69.74813616640164,
                    70.47333615344107,
                    71.20291564160104,
                    71.93688215501312,
                    72.67524319850172,
                    73.41800625771542,
                    74.16517879925733,
                    74.9167682708136,
                    75.67278210128072,
                    76.43322770089146,
                    77.1981124613393,
                    77.96744375590167,
                    78.74122893956174,
                    79.51947534912904,
                    80.30219030335869,
                    81.08938110306934,
                    81.88105503125999,
                    82.67721935322541,
                    83.4778813166706,
                    84.28304815182372,
                    85.09272707154808,
                    85.90692527145302,
                    86.72564993000343,
                    87.54890820862819,
                    88.3767072518277,
                    89.2090541872801,
                    90.04595612594655,
                    90.88742016217518,
                    91.73345337380438,
                    92.58406282226491,
                    93.43925555268066,
                    94.29903859396902,
                    95.16341895893969,
                    96.03240364439274,
                    96.9059996312159,
                    97.78421388448044,
                    98.6670533535366,
                    99.55452497210776,
            };

    /**
     * Sanitizes a small enough angle in radians.
     *
     * @param angle An angle in radians; must not deviate too much from 0.
     * @return A coterminal angle between 0 and 2pi.
     */
    static double sanitizeRadians(double angle) {
        return (angle + Math.PI * 8) % (Math.PI * 2);
    }

    /**
     * Delinearizes an RGB component, returning a floating-point number.
     *
     * @param rgbComponent 0.0 <= rgb_component <= 100.0, represents linear R/G/B channel
     * @return 0.0 <= output <= 255.0, color channel converted to regular RGB space
     */
    static double trueDelinearized(double rgbComponent) {
        double normalized = rgbComponent / 100.0;
        double delinearized;
        if (normalized <= 0.0031308) {
            delinearized = normalized * 12.92;
        } else {
            delinearized = 1.055 * Math.pow(normalized, 1.0 / 2.4) - 0.055;
        }
        return delinearized * 255.0;
    }

    static double chromaticAdaptation(double component) {
        double af = Math.pow(Math.abs(component), 0.42);
        return CamUtils.signum(component) * 400.0 * af / (af + 27.13);
    }

    /**
     * Returns the hue of a linear RGB color in CAM16.
     *
     * @param linrgb The linear RGB coordinates of a color.
     * @return The hue of the color in CAM16, in radians.
     */
    static double hueOf(double[] linrgb) {
        // Calculate scaled discount components using in-lined matrix multiplication to avoid
        // an array allocation.
        double[][] matrix = SCALED_DISCOUNT_FROM_LINRGB;
        double[] row = linrgb;
        double rD = linrgb[0] * matrix[0][0] + row[1] * matrix[0][1] + row[2] * matrix[0][2];
        double gD = linrgb[0] * matrix[1][0] + row[1] * matrix[1][1] + row[2] * matrix[1][2];
        double bD = linrgb[0] * matrix[2][0] + row[1] * matrix[2][1] + row[2] * matrix[2][2];

        double rA = chromaticAdaptation(rD);
        double gA = chromaticAdaptation(gD);
        double bA = chromaticAdaptation(bD);
        // redness-greenness
        double a = (11.0 * rA + -12.0 * gA + bA) / 11.0;
        // yellowness-blueness
        double b = (rA + gA - 2.0 * bA) / 9.0;
        return Math.atan2(b, a);
    }

    /**
     * Cyclic order is the idea that 330° → 5° → 200° is in order, but, 180° → 270° → 210° is not.
     * Visually, A B and C are angles, and they are in cyclic order if travelling from A to C
     * in a way that increases angle (ex. counter-clockwise if +x axis = 0 degrees and +y = 90)
     * means you must cross B.
     * @param a first angle in possibly cyclic triplet
     * @param b second angle in possibly cyclic triplet
     * @param c third angle in possibly cyclic triplet
     * @return true if B is between A and C
     */
    static boolean areInCyclicOrder(double a, double b, double c) {
        double deltaAB = sanitizeRadians(b - a);
        double deltaAC = sanitizeRadians(c - a);
        return deltaAB < deltaAC;
    }

    /**
     * Find an intercept using linear interpolation.
     *
     * @param source The starting number.
     * @param mid The number in the middle.
     * @param target The ending number.
     * @return A number t such that lerp(source, target, t) = mid.
     */
    static double intercept(double source, double mid, double target) {
        if (target == source) {
            return target;
        }
        return (mid - source) / (target - source);
    }

    /**
     * Linearly interpolate between two points in three dimensions.
     *
     * @param source three dimensions representing the starting point
     * @param t the percentage to travel between source and target, from 0 to 1
     * @param target three dimensions representing the end point
     * @return three dimensions representing the point t percent from source to target.
     */
    static double[] lerpPoint(double[] source, double t, double[] target) {
        return new double[] {
                source[0] + (target[0] - source[0]) * t,
                source[1] + (target[1] - source[1]) * t,
                source[2] + (target[2] - source[2]) * t,
        };
    }

    /**
     * Intersects a segment with a plane.
     *
     * @param source The coordinates of point A.
     * @param coordinate The R-, G-, or B-coordinate of the plane.
     * @param target The coordinates of point B.
     * @param axis The axis the plane is perpendicular with. (0: R, 1: G, 2: B)
     * @return The intersection point of the segment AB with the plane R=coordinate, G=coordinate,
     *     or B=coordinate
     */
    static double[] setCoordinate(double[] source, double coordinate, double[] target, int axis) {
        double t = intercept(source[axis], coordinate, target[axis]);
        return lerpPoint(source, t, target);
    }

    /** Ensure X is between 0 and 100. */
    static boolean isBounded(double x) {
        return 0.0 <= x && x <= 100.0;
    }

    /**
     * Returns the nth possible vertex of the polygonal intersection.
     *
     * @param y The Y value of the plane.
     * @param n The zero-based index of the point. 0 <= n <= 11.
     * @return The nth possible vertex of the polygonal intersection of the y plane and the RGB cube
     *     in linear RGB coordinates, if it exists. If the possible vertex lies outside of the cube,
     *     [-1.0, -1.0, -1.0] is returned.
     */
    static double[] nthVertex(double y, int n) {
        double kR = Y_FROM_LINRGB[0];
        double kG = Y_FROM_LINRGB[1];
        double kB = Y_FROM_LINRGB[2];
        double coordA = n % 4 <= 1 ? 0.0 : 100.0;
        double coordB = n % 2 == 0 ? 0.0 : 100.0;
        if (n < 4) {
            double g = coordA;
            double b = coordB;
            double r = (y - g * kG - b * kB) / kR;
            if (isBounded(r)) {
                return new double[] {r, g, b};
            } else {
                return new double[] {-1.0, -1.0, -1.0};
            }
        } else if (n < 8) {
            double b = coordA;
            double r = coordB;
            double g = (y - r * kR - b * kB) / kG;
            if (isBounded(g)) {
                return new double[] {r, g, b};
            } else {
                return new double[] {-1.0, -1.0, -1.0};
            }
        } else {
            double r = coordA;
            double g = coordB;
            double b = (y - r * kR - g * kG) / kB;
            if (isBounded(b)) {
                return new double[] {r, g, b};
            } else {
                return new double[] {-1.0, -1.0, -1.0};
            }
        }
    }

    /**
     * Finds the segment containing the desired color.
     *
     * @param y The Y value of the color.
     * @param targetHue The hue of the color.
     * @return A list of two sets of linear RGB coordinates, each corresponding to an endpoint of
     *     the segment containing the desired color.
     */
    static double[][] bisectToSegment(double y, double targetHue) {
        double[] left = new double[] {-1.0, -1.0, -1.0};
        double[] right = left;
        double leftHue = 0.0;
        double rightHue = 0.0;
        boolean initialized = false;
        boolean uncut = true;
        for (int n = 0; n < 12; n++) {
            double[] mid = nthVertex(y, n);
            if (mid[0] < 0) {
                continue;
            }
            double midHue = hueOf(mid);
            if (!initialized) {
                left = mid;
                right = mid;
                leftHue = midHue;
                rightHue = midHue;
                initialized = true;
                continue;
            }
            if (uncut || areInCyclicOrder(leftHue, midHue, rightHue)) {
                uncut = false;
                if (areInCyclicOrder(leftHue, targetHue, midHue)) {
                    right = mid;
                    rightHue = midHue;
                } else {
                    left = mid;
                    leftHue = midHue;
                }
            }
        }
        return new double[][] {left, right};
    }

    static int criticalPlaneBelow(double x) {
        return (int) Math.floor(x - 0.5);
    }

    static int criticalPlaneAbove(double x) {
        return (int) Math.ceil(x - 0.5);
    }

    /**
     * Finds a color with the given Y and hue on the boundary of the cube.
     *
     * @param y The Y value of the color.
     * @param targetHue The hue of the color.
     * @return The desired color, in linear RGB coordinates.
     */
    static int bisectToLimit(double y, double targetHue) {
        double[][] segment = bisectToSegment(y, targetHue);
        double[] left = segment[0];
        double leftHue = hueOf(left);
        double[] right = segment[1];
        for (int axis = 0; axis < 3; axis++) {
            if (left[axis] != right[axis]) {
                int lPlane = -1;
                int rPlane = 255;
                if (left[axis] < right[axis]) {
                    lPlane = criticalPlaneBelow(trueDelinearized(left[axis]));
                    rPlane = criticalPlaneAbove(trueDelinearized(right[axis]));
                } else {
                    lPlane = criticalPlaneAbove(trueDelinearized(left[axis]));
                    rPlane = criticalPlaneBelow(trueDelinearized(right[axis]));
                }
                for (int i = 0; i < 8; i++) {
                    if (Math.abs(rPlane - lPlane) <= 1) {
                        break;
                    } else {
                        int mPlane = (int) Math.floor((lPlane + rPlane) / 2.0);
                        double midPlaneCoordinate = CRITICAL_PLANES[mPlane];
                        double[] mid = setCoordinate(left, midPlaneCoordinate, right, axis);
                        double midHue = hueOf(mid);
                        if (areInCyclicOrder(leftHue, targetHue, midHue)) {
                            right = mid;
                            rPlane = mPlane;
                        } else {
                            left = mid;
                            leftHue = midHue;
                            lPlane = mPlane;
                        }
                    }
                }
            }
        }
        return CamUtils.argbFromLinrgbComponents((left[0] + right[0]) / 2,
                (left[1] + right[1]) / 2, (left[2] + right[2]) / 2);
    }

    /** Equation used in CAM16 conversion that removes the effect of chromatic adaptation. */
    static double inverseChromaticAdaptation(double adapted) {
        double adaptedAbs = Math.abs(adapted);
        double base = Math.max(0, 27.13 * adaptedAbs / (400.0 - adaptedAbs));
        return CamUtils.signum(adapted) * Math.pow(base, 1.0 / 0.42);
    }

    /**
     * Finds a color with the given hue, chroma, and Y.
     *
     * @param hueRadians The desired hue in radians.
     * @param chroma The desired chroma.
     * @param y The desired Y.
     * @return The desired color as a hexadecimal integer, if found; 0 otherwise.
     */
    static int findResultByJ(double hueRadians, double chroma, double y) {
        // Initial estimate of j.
        double j = Math.sqrt(y) * 11.0;
        // ===========================================================
        // Operations inlined from Cam16 to avoid repeated calculation
        // ===========================================================
        Frame viewingConditions = Frame.DEFAULT;
        double tInnerCoeff = 1 / Math.pow(1.64 - Math.pow(0.29, viewingConditions.getN()), 0.73);
        double eHue = 0.25 * (Math.cos(hueRadians + 2.0) + 3.8);
        double p1 = eHue * (50000.0 / 13.0) * viewingConditions.getNc()
                * viewingConditions.getNcb();
        double hSin = Math.sin(hueRadians);
        double hCos = Math.cos(hueRadians);
        for (int iterationRound = 0; iterationRound < 5; iterationRound++) {
            // ===========================================================
            // Operations inlined from Cam16 to avoid repeated calculation
            // ===========================================================
            double jNormalized = j / 100.0;
            double alpha = chroma == 0.0 || j == 0.0 ? 0.0 : chroma / Math.sqrt(jNormalized);
            double t = Math.pow(alpha * tInnerCoeff, 1.0 / 0.9);
            double acExponent = 1.0 / viewingConditions.getC() / viewingConditions.getZ();
            double ac = viewingConditions.getAw() * Math.pow(jNormalized, acExponent);
            double p2 = ac / viewingConditions.getNbb();
            double gamma = 23.0 * (p2 + 0.305) * t / (23.0 * p1 + 11 * t * hCos + 108.0 * t * hSin);
            double a = gamma * hCos;
            double b = gamma * hSin;
            double rA = (460.0 * p2 + 451.0 * a + 288.0 * b) / 1403.0;
            double gA = (460.0 * p2 - 891.0 * a - 261.0 * b) / 1403.0;
            double bA = (460.0 * p2 - 220.0 * a - 6300.0 * b) / 1403.0;
            double rCScaled = inverseChromaticAdaptation(rA);
            double gCScaled = inverseChromaticAdaptation(gA);
            double bCScaled = inverseChromaticAdaptation(bA);
            double[][] matrix = LINRGB_FROM_SCALED_DISCOUNT;
            double linrgbR = rCScaled * matrix[0][0] + gCScaled * matrix[0][1]
                    + bCScaled * matrix[0][2];
            double linrgbG = rCScaled * matrix[1][0] + gCScaled * matrix[1][1]
                    + bCScaled * matrix[1][2];
            double linrgbB = rCScaled * matrix[2][0] + gCScaled * matrix[2][1]
                    + bCScaled * matrix[2][2];
            // ===========================================================
            // Operations inlined from Cam16 to avoid repeated calculation
            // ===========================================================
            if (linrgbR < 0 || linrgbG < 0 || linrgbB < 0) {
                return 0;
            }
            double kR = Y_FROM_LINRGB[0];
            double kG = Y_FROM_LINRGB[1];
            double kB = Y_FROM_LINRGB[2];
            double fnj = kR * linrgbR + kG * linrgbG + kB * linrgbB;
            if (fnj <= 0) {
                return 0;
            }
            if (iterationRound == 4 || Math.abs(fnj - y) < 0.002) {
                if (linrgbR > 100.01 || linrgbG > 100.01 || linrgbB > 100.01) {
                    return 0;
                }
                return CamUtils.argbFromLinrgbComponents(linrgbR, linrgbG, linrgbB);
            }
            // Iterates with Newton method,
            // Using 2 * fn(j) / j as the approximation of fn'(j)
            j = j - (fnj - y) * j / (2 * fnj);
        }
        return 0;
    }

    /**
     * Finds an sRGB color with the given hue, chroma, and L*, if possible.
     *
     * @param hueDegrees The desired hue, in degrees.
     * @param chroma The desired chroma.
     * @param lstar The desired L*.
     * @return A hexadecimal representing the sRGB color. The color has sufficiently close hue,
     *     chroma, and L* to the desired values, if possible; otherwise, the hue and L* will be
     *     sufficiently close, and chroma will be maximized.
     */
    public static int solveToInt(double hueDegrees, double chroma, double lstar) {
        if (chroma < 0.0001 || lstar < 0.0001 || lstar > 99.9999) {
            return CamUtils.argbFromLstar(lstar);
        }
        hueDegrees = sanitizeDegreesDouble(hueDegrees);
        double hueRadians = Math.toRadians(hueDegrees);
        double y = CamUtils.yFromLstar(lstar);
        int exactAnswer = findResultByJ(hueRadians, chroma, y);
        if (exactAnswer != 0) {
            return exactAnswer;
        }
        return bisectToLimit(y, hueRadians);
    }

    /**
     * Sanitizes a degree measure as a floating-point number.
     *
     * @return a degree measure between 0.0 (inclusive) and 360.0 (exclusive).
     */
    public static double sanitizeDegreesDouble(double degrees) {
        degrees = degrees % 360.0;
        if (degrees < 0) {
            degrees = degrees + 360.0;
        }
        return degrees;
    }

    /**
     * Finds an sRGB color with the given hue, chroma, and L*, if possible.
     *
     * @param hueDegrees The desired hue, in degrees.
     * @param chroma The desired chroma.
     * @param lstar The desired L*.
     * @return An CAM16 object representing the sRGB color. The color has sufficiently close hue,
     *     chroma, and L* to the desired values, if possible; otherwise, the hue and L* will be
     *     sufficiently close, and chroma will be maximized.
     */
    public static Cam solveToCam(double hueDegrees, double chroma, double lstar) {
        return Cam.fromInt(solveToInt(hueDegrees, chroma, lstar));
    }
}