/**
 * @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[0] = a.mV[0];
    mV[1] = a.mV[1];
    mV[2] = a.mV[2];
}

LLColor3::LLColor3(const LLVector4 &a)
{
    mV[0] = a.mV[0];
    mV[1] = a.mV[1];
    mV[2] = a.mV[2];
}

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

const LLColor3& LLColor3::operator=(const LLColor4 &a)
{
    mV[0] = a.mV[0];
    mV[1] = a.mV[1];
    mV[2] = a.mV[2];
    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;
}