Spring.cpp

/***************************************************************************
 *   This file is part of OpenCAL: Open Computer Animation Library         *
 *   I created OpenCAL as my master's thesis Computer Science (multimedia) *
 *   at the tUL university in Diepenbeek, Belgium                          *
 *                                                                         *
 *   Copyright (C) 2003-2004 by Jeroen Dierckx                             *
 *   jeroen.dierckx@student.luc.ac.be                                      *
 *                                                                         *
 ***************************************************************************/

// Includes
#include "Spring.h"
#include <OpenCAL/PhysicalObject.h>
#include <OpenCAL/System.h>
#include <OpenCAL/Renderer.h>
using namespace OpenCAL;

#include <OpenCAL/Material.h>
#include <OpenCAL/Color.h>
using namespace Utils;

using namespace std;


/******************************
* Constructors and destructor *
******************************/

Spring::Spring(PhysicsSystem *parent, PhysicalObject *object1, PhysicalObject *object2)
: Force(parent), m_object1(object1), m_object2(object2), m_stiffness(0.1f),
    m_damping(0.1f), m_restLength(0.0f), m_snapFactor(0.0f)
{
}

Spring::~Spring()
{
}


/************************
* Get and set functions *
************************/


/********************
* Execute functions *
********************/

void Spring::initialize()
{
    Force::initialize();

    // Only calculate the rest length if not set by the user
    if(m_restLength == 0.0f)
        calculateRestLength();
}

void Spring::execute(float seconds)
{
    //if(!m_enabled) return;
    if(!isConnected()) return;
    Force::execute(seconds);

    if(!m_object1 || !m_object2) return; 

    Vector3 deltaP = m_object1->getPosition() - m_object2->getPosition();
    Vector3 deltaV = m_object1->getVelocity() - m_object2->getVelocity();
    float length = deltaP.length();

    float term1 = -m_stiffness * (length - m_restLength);
    float term2 = -m_damping * deltaV.dotProduct(deltaP) / length;

    Vector3 force = (term1 + term2) * deltaP.normalized();

    m_object1->addForce(force);
    m_object2->addForce(-force);

    // If the length of the spring is greater than it's maximum, 'snap' the spring
    if(m_snapFactor > 1.0f && length > (m_restLength * m_snapFactor))
        m_object1 = m_object2 = 0;
}


/*******************
* Render functions *
*******************/

void Spring::render()
{
    Renderer *renderer = m_parent->getRenderer();
    if(!renderer) return;

    //if(!m_draw) return;
    if(!m_enabled) return;
    if(!isConnected()) return;

    renderer->renderLine(m_object1->getPosition(), m_object2->getPosition(), 3.0f);
}


/******************
* Other functions *
******************/

void Spring::calculateRestLength( )
{
    if(!m_object1 || !m_object2)
        m_restLength = 0.0f;
    else
        m_restLength = m_object1->getPosition().distance(m_object2->getPosition());
}

/*
#ifdef USE_OPENGL
void Spring::drawGL()
{
    //if(!m_draw) return;
    if(!m_enabled) return;
    if(!isConnected()) return;

    Material mat;
    mat.setAmbient(Color::green);
    mat.setDiffuse(Color::green);
    mat.applyGL();

    glLineWidth(3.0f);

    // Draw the spring
    glBegin(GL_LINES);
        glVertex3fv(m_object1->getPosition());
        glVertex3fv(m_object2->getPosition());
    glEnd();
}
#endif // USE_OPENGL
*/


/**********************
* Protected functions *
**********************/

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