source: sandbox_light/src/external/ogremath/OgreColourValue.cpp @ 6563

/*
-----------------------------------------------------------------------------
This source file is part of OGRE
    (Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org/

Copyright (c) 2000-2006 Torus Knot Software Ltd
Also see acknowledgements in Readme.html

This program 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; either version 2 of the License, or (at your option) any later
version.

This program 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 program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place - Suite 330, Boston, MA 02111-1307, USA, or go to
http://www.gnu.org/copyleft/lesser.txt.

You may alternatively use this source under the terms of a specific version of
the OGRE Unrestricted License provided you have obtained such a license from
Torus Knot Software Ltd.
-----------------------------------------------------------------------------
*/
#include "OgreColourValue.h"
#include "OgreMath.h"

namespace Ogre {

    const ColourValue ColourValue::ZERO = ColourValue(0.0,0.0,0.0,0.0);
    const ColourValue ColourValue::Black = ColourValue(0.0,0.0,0.0);
    const ColourValue ColourValue::White = ColourValue(1.0,1.0,1.0);
    const ColourValue ColourValue::Red = ColourValue(1.0,0.0,0.0);
    const ColourValue ColourValue::Green = ColourValue(0.0,1.0,0.0);
    const ColourValue ColourValue::Blue = ColourValue(0.0,0.0,1.0);

    //---------------------------------------------------------------------
#if OGRE_ENDIAN == OGRE_ENDIAN_BIG
    ABGR ColourValue::getAsABGR(void) const
#else
    RGBA ColourValue::getAsRGBA(void) const
#endif
    {
        uint8 val8;
        uint32 val32 = 0;

        // Convert to 32bit pattern
        // (RGBA = 8888)

        // Red
        val8 = static_cast<uint8>(r * 255);
        val32 = val8 << 24;

        // Green
        val8 = static_cast<uint8>(g * 255);
        val32 += val8 << 16;

        // Blue
        val8 = static_cast<uint8>(b * 255);
        val32 += val8 << 8;

        // Alpha
        val8 = static_cast<uint8>(a * 255);
        val32 += val8;

        return val32;
    }
    //---------------------------------------------------------------------
#if OGRE_ENDIAN == OGRE_ENDIAN_BIG
    BGRA ColourValue::getAsBGRA(void) const
#else
    ARGB ColourValue::getAsARGB(void) const
#endif
    {
        uint8 val8;
        uint32 val32 = 0;

        // Convert to 32bit pattern
        // (ARGB = 8888)

        // Alpha
        val8 = static_cast<uint8>(a * 255);
        val32 = val8 << 24;

        // Red
        val8 = static_cast<uint8>(r * 255);
        val32 += val8 << 16;

        // Green
        val8 = static_cast<uint8>(g * 255);
        val32 += val8 << 8;

        // Blue
        val8 = static_cast<uint8>(b * 255);
        val32 += val8;


        return val32;
    }
        //---------------------------------------------------------------------
#if OGRE_ENDIAN == OGRE_ENDIAN_BIG
        ARGB ColourValue::getAsARGB(void) const
#else
        BGRA ColourValue::getAsBGRA(void) const
#endif
        {
                uint8 val8;
                uint32 val32 = 0;

                // Convert to 32bit pattern
                // (ARGB = 8888)

                // Blue
                val8 = static_cast<uint8>(b * 255);
                val32 = val8 << 24;

                // Green
                val8 = static_cast<uint8>(g * 255);
                val32 += val8 << 16;

                // Red
                val8 = static_cast<uint8>(r * 255);
                val32 += val8 << 8;

                // Alpha
                val8 = static_cast<uint8>(a * 255);
                val32 += val8;


                return val32;
        }
    //---------------------------------------------------------------------
#if OGRE_ENDIAN == OGRE_ENDIAN_BIG
    RGBA ColourValue::getAsRGBA(void) const
#else
    ABGR ColourValue::getAsABGR(void) const
#endif
    {
        uint8 val8;
        uint32 val32 = 0;

        // Convert to 32bit pattern
        // (ABRG = 8888)

        // Alpha
        val8 = static_cast<uint8>(a * 255);
        val32 = val8 << 24;

        // Blue
        val8 = static_cast<uint8>(b * 255);
        val32 += val8 << 16;

        // Green
        val8 = static_cast<uint8>(g * 255);
        val32 += val8 << 8;

        // Red
        val8 = static_cast<uint8>(r * 255);
        val32 += val8;


        return val32;
    }
    //---------------------------------------------------------------------
#if OGRE_ENDIAN == OGRE_ENDIAN_BIG
    void ColourValue::setAsABGR(const ABGR val)
#else
    void ColourValue::setAsRGBA(const RGBA val)
#endif
    {
        uint32 val32 = val;

        // Convert from 32bit pattern
        // (RGBA = 8888)

        // Red
        r = ((val32 >> 24) & 0xFF) / 255.0f;

        // Green
        g = ((val32 >> 16) & 0xFF) / 255.0f;

        // Blue
        b = ((val32 >> 8) & 0xFF) / 255.0f;

        // Alpha
        a = (val32 & 0xFF) / 255.0f;
    }
    //---------------------------------------------------------------------
#if OGRE_ENDIAN == OGRE_ENDIAN_BIG
    void ColourValue::setAsBGRA(const BGRA val)
#else
    void ColourValue::setAsARGB(const ARGB val)
#endif
    {
        uint32 val32 = val;

        // Convert from 32bit pattern
        // (ARGB = 8888)

        // Alpha
        a = ((val32 >> 24) & 0xFF) / 255.0f;

        // Red
        r = ((val32 >> 16) & 0xFF) / 255.0f;

        // Green
        g = ((val32 >> 8) & 0xFF) / 255.0f;

        // Blue
        b = (val32 & 0xFF) / 255.0f;
    }
        //---------------------------------------------------------------------
#if OGRE_ENDIAN == OGRE_ENDIAN_BIG
        void ColourValue::setAsARGB(const ARGB val)
#else
        void ColourValue::setAsBGRA(const BGRA val)
#endif
        {
                uint32 val32 = val;

                // Convert from 32bit pattern
                // (ARGB = 8888)

                // Blue
                b = ((val32 >> 24) & 0xFF) / 255.0f;

                // Green
                g = ((val32 >> 16) & 0xFF) / 255.0f;

                // Red
                r = ((val32 >> 8) & 0xFF) / 255.0f;

                // Alpha
                a = (val32 & 0xFF) / 255.0f;
        }
    //---------------------------------------------------------------------
#if OGRE_ENDIAN == OGRE_ENDIAN_BIG
    void ColourValue::setAsRGBA(const RGBA val)
#else
    void ColourValue::setAsABGR(const ABGR val)
#endif
    {
        uint32 val32 = val;

        // Convert from 32bit pattern
        // (ABGR = 8888)

        // Alpha
        a = ((val32 >> 24) & 0xFF) / 255.0f;

        // Blue
        b = ((val32 >> 16) & 0xFF) / 255.0f;

        // Green
        g = ((val32 >> 8) & 0xFF) / 255.0f;

        // Red
        r = (val32 & 0xFF) / 255.0f;
    }
    //---------------------------------------------------------------------
    bool ColourValue::operator==(const ColourValue& rhs) const
    {
        return (r == rhs.r &&
            g == rhs.g &&
            b == rhs.b &&
            a == rhs.a);
    }
    //---------------------------------------------------------------------
    bool ColourValue::operator!=(const ColourValue& rhs) const
    {
        return !(*this == rhs);
    }
        //---------------------------------------------------------------------
        void ColourValue::setHSB(Real hue, Real saturation, Real brightness)
        {
                // wrap hue
                if (hue > 1.0f)
                {
                        hue -= (int)hue;
                }
                else if (hue < 0.0f)
                {
                        hue += (int)hue + 1;
                }
                // clamp saturation / brightness
                saturation = std::min(saturation, (Real)1.0);
                saturation = std::max(saturation, (Real)0.0);
                brightness = std::min(brightness, (Real)1.0);
                brightness = std::max(brightness, (Real)0.0);

                if (brightness == 0.0f)
                {   
                        // early exit, this has to be black
                        r = g = b = 0.0f;
                        return;
                }

                if (saturation == 0.0f)
                {   
                        // early exit, this has to be grey

                        r = g = b = brightness;
                        return;
                }


                Real hueDomain  = hue * 6.0f;
                if (hueDomain >= 6.0f)
                {
                        // wrap around, and allow mathematical errors
                        hueDomain = 0.0f;
                }
                unsigned short domain = (unsigned short)hueDomain;
                Real f1 = brightness * (1 - saturation);
                Real f2 = brightness * (1 - saturation * (hueDomain - domain));
                Real f3 = brightness * (1 - saturation * (1 - (hueDomain - domain)));

                switch (domain)
                {
                case 0:
                        // red domain; green ascends
                        r = brightness;
                        g = f3;
                        b = f1;
                        break;
                case 1:
                        // yellow domain; red descends
                        r = f2;
                        g = brightness;
                        b = f1;
                        break;
                case 2:
                        // green domain; blue ascends
                        r = f1;
                        g = brightness;
                        b = f3;
                        break;
                case 3:
                        // cyan domain; green descends
                        r = f1;
                        g = f2;
                        b = brightness;
                        break;
                case 4:
                        // blue domain; red ascends
                        r = f3;
                        g = f1;
                        b = brightness;
                        break;
                case 5:
                        // magenta domain; blue descends
                        r = brightness;
                        g = f1;
                        b = f2;
                        break;
                }


        }
        //---------------------------------------------------------------------
        void ColourValue::getHSB(Real* hue, Real* saturation, Real* brightness) const
        {

                Real vMin = std::min(r, std::min(g, b));
                Real vMax = std::max(r, std::max(g, b));
                Real delta = vMax - vMin;

                *brightness = vMax;

                if (Math::RealEqual(delta, 0.0f, 1e-6))
                {
                        // grey
                        *hue = 0;
                        *saturation = 0;
                }
                else                                    
                {
                        // a colour
                        *saturation = delta / vMax;

                        Real deltaR = (((vMax - r) / 6.0f) + (delta / 2.0f)) / delta;
                        Real deltaG = (((vMax - g) / 6.0f) + (delta / 2.0f)) / delta;
                        Real deltaB = (((vMax - b) / 6.0f) + (delta / 2.0f)) / delta;

                        if (Math::RealEqual(r, vMax))
                                *hue = deltaB - deltaG;
                        else if (Math::RealEqual(g, vMax))
                                *hue = 0.3333333f + deltaR - deltaB;
                        else if (Math::RealEqual(b, vMax)) 
                                *hue = 0.6666667f + deltaG - deltaR;

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

                
        }

}