/**
 * @file v3color.cpp
 * @brief LLColor3 class implementation.
 *
 * $LicenseInfo:firstyear=2000&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2010, Linden Research, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License only.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 */

#include "linden_common.h"

#include "v3color.h"
#include "v4color.h"
#include "v4math.h"

LLColor3 LLColor3::white(1.0f, 1.0f, 1.0f);
LLColor3 LLColor3::black(0.0f, 0.0f, 0.0f);
LLColor3 LLColor3::grey(0.5f, 0.5f, 0.5f);

LLColor3::LLColor3(const LLColor4& a)
{
    mV[VRED]   = a.mV[VRED];
    mV[VGREEN] = a.mV[VGREEN];
    mV[VBLUE]  = a.mV[VBLUE];
}

LLColor3::LLColor3(const LLVector4& a)
{
    mV[VRED]   = a.mV[VRED];
    mV[VGREEN] = a.mV[VGREEN];
    mV[VBLUE]  = a.mV[VBLUE];
}

LLColor3::LLColor3(const LLSD& sd)
{
    setValue(sd);
}

const LLColor3& LLColor3::operator=(const LLColor4& a)
{
    mV[VRED]   = a.mV[VRED];
    mV[VGREEN] = a.mV[VGREEN];
    mV[VBLUE]  = a.mV[VBLUE];
    return (*this);
}

std::ostream& operator<<(std::ostream& s, const LLColor3& a)
{
    s << "{ " << a.mV[VRED] << ", " << a.mV[VGREEN] << ", " << a.mV[VBLUE] << " }";
    return s;
}

static F32 hueToRgb(F32 val1In, F32 val2In, F32 valHUeIn)
{
    if (valHUeIn < 0.0f)
        valHUeIn += 1.0f;
    if (valHUeIn > 1.0f)
        valHUeIn -= 1.0f;
    if ((6.0f * valHUeIn) < 1.0f)
        return (val1In + (val2In - val1In) * 6.0f * valHUeIn);
    if ((2.0f * valHUeIn) < 1.0f)
        return (val2In);
    if ((3.0f * valHUeIn) < 2.0f)
        return (val1In + (val2In - val1In) * ((2.0f / 3.0f) - valHUeIn) * 6.0f);
    return (val1In);
}

void LLColor3::setHSL(F32 hValIn, F32 sValIn, F32 lValIn)
{
    if (sValIn < 0.00001f)
    {
        mV[VRED]   = lValIn;
        mV[VGREEN] = lValIn;
        mV[VBLUE]  = lValIn;
    }
    else
    {
        F32 interVal1;
        F32 interVal2;

        if (lValIn < 0.5f)
            interVal2 = lValIn * (1.0f + sValIn);
        else
            interVal2 = (lValIn + sValIn) - (sValIn * lValIn);

        interVal1 = 2.0f * lValIn - interVal2;

        mV[VRED]   = hueToRgb(interVal1, interVal2, hValIn + (1.f / 3.f));
        mV[VGREEN] = hueToRgb(interVal1, interVal2, hValIn);
        mV[VBLUE]  = hueToRgb(interVal1, interVal2, hValIn - (1.f / 3.f));
    }
}

void LLColor3::calcHSL(F32* hue, F32* saturation, F32* luminance) const
{
    F32 var_R = mV[VRED];
    F32 var_G = mV[VGREEN];
    F32 var_B = mV[VBLUE];

    F32 var_Min = (var_R < (var_G < var_B ? var_G : var_B) ? var_R : (var_G < var_B ? var_G : var_B));
    F32 var_Max = (var_R > (var_G > var_B ? var_G : var_B) ? var_R : (var_G > var_B ? var_G : var_B));

    F32 del_Max = var_Max - var_Min;

    F32 L = (var_Max + var_Min) / 2.0f;
    F32 H = 0.0f;
    F32 S = 0.0f;

    if (del_Max == 0.0f)
    {
        H = 0.0f;
        S = 0.0f;
    }
    else
    {
        if (L < 0.5)
            S = del_Max / (var_Max + var_Min);
        else
            S = del_Max / (2.0f - var_Max - var_Min);

        F32 del_R = (((var_Max - var_R) / 6.0f) + (del_Max / 2.0f)) / del_Max;
        F32 del_G = (((var_Max - var_G) / 6.0f) + (del_Max / 2.0f)) / del_Max;
        F32 del_B = (((var_Max - var_B) / 6.0f) + (del_Max / 2.0f)) / del_Max;

        if (var_R >= var_Max)
            H = del_B - del_G;
        else if (var_G >= var_Max)
            H = (1.0f / 3.0f) + del_R - del_B;
        else if (var_B >= var_Max)
            H = (2.0f / 3.0f) + del_G - del_R;

        if (H < 0.0f)
            H += 1.0f;
        if (H > 1.0f)
            H -= 1.0f;
    }

    if (hue)
        *hue = H;
    if (saturation)
        *saturation = S;
    if (luminance)
        *luminance = L;
}