MercuryLight.cpp

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#include "MercuryLight.h"
#include "MercuryDisplay.h"
#include "MercuryMath.h"

MercuryLight::MercuryLight()
:MercuryObject()
{
}

MercuryLight::~MercuryLight()
{
    DISPLAY->RemoveLight(this);
}

void MercuryLight::Init()
{
    MercuryObject::Init();

    //  m_colors.m_diffuse = MercuryColor(1.0f, 1.0f, 1.0f, 1.0f);
    m_colors.m_specular = m_colors.m_diffuse = m_colors.m_ambient = MercuryColor(1.0f, 1.0f, 1.0f, 1.0f);

    m_attenuation[Attenuation::CONSTANT].value = 1; //Default
    m_attenuation[Attenuation::LINEAR].type = Attenuation::LINEAR;
    m_attenuation[Attenuation::QUADRATIC].type = Attenuation::QUADRATIC;

    m_pLT = LT_DIRECTIONAL;

    m_static = false;

    SetMaterial(&m_colors);
    ComputeRadius();
}

void MercuryLight::SetAttenuation(float value, Attenuation::Type type)
{
    m_attenuation[type].type = type;
    m_attenuation[type].value = value;
    ComputeRadius();
}

float MercuryLight::ComputeBrightnessFromDistance(const MercuryPoint& objectPos) const
{
    float dist = (GetPosition() - objectPos).Magnitude();
    float atten = 1.0f / ( m_attenuation[Attenuation::CONSTANT].value + m_attenuation[Attenuation::LINEAR].value*dist + m_attenuation[Attenuation::QUADRATIC].value*dist*dist);
    float ac = (m_finalMaterial.m_ambient.GetR() + m_finalMaterial.m_ambient.GetG() + m_finalMaterial.m_ambient.GetB()) * atten;
    float dc = (m_finalMaterial.m_diffuse.GetR() + m_finalMaterial.m_diffuse.GetG() + m_finalMaterial.m_diffuse.GetB()) * atten;
    float sc = (m_finalMaterial.m_specular.GetR() + m_finalMaterial.m_specular.GetG() + m_finalMaterial.m_specular.GetB()) * atten;
    return ac + dc + sc;
}

void MercuryLight::ComputeRadius()
{
    //300 ensures that RGB of 255 reaches 0
    //at 50, 255 is about 5. Close enough for me
    const float maxDenom = 50;//300;
    float a = m_attenuation[Attenuation::QUADRATIC].value;
    float b = m_attenuation[Attenuation::LINEAR].value;
    float c = m_attenuation[Attenuation::CONSTANT].value;
    float d = 0;

    if ((a == 0)&&(b == 0))
    {
        d = 1000.0;
    }
    else if (a == 0)
    {
        d = (maxDenom - c)/b;
    }
    else if (b == 0)
    {
        d = SQRT((maxDenom - c)/a);
    }
    else
    {
        //reciprocal of the quadratic equation
        float bottom = 2*a;
        float s = SQRT((b*b)-(4*a*c));
        float x1 = ((-b) - s)/bottom;
        float x2 = ((-b) + s)/bottom;
        m_radius = max(x1,x2);
    }

    m_radius = d;
}

#include "MercuryObjectFactory.h"
REGISTER_OBJECT_TYPE( MercuryLight );

/* 
 * Copyright (c) 2005-2006, Joshua Allen
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *  -   Redistributions of source code must retain the above
 *      copyright notice, this list of conditions and the following disclaimer.
 *  -   Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in
 *      the documentation and/or other materials provided with the distribution.
 *  -   Neither the name of the Mercury Engine nor the names of its
 *      contributors may be used to endorse or promote products derived from
 *      this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

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