PressureForce.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 "PressureForce.h"
#include <OpenCAL/BalloonMesh.h>
#include <OpenCAL/Vertex.h>
#include <OpenCAL/PointMass.h>
#include <OpenCAL/Triangle.h>
using namespace OpenCAL;

using namespace std;


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

PressureForce::PressureForce(BalloonMesh *parent)
: Force(parent), m_idealGasConstant(8.314570f), m_numMoles(0.1f), m_temperature(293.0f)
{
    m_numMoles = 0.0001f;
}

PressureForce::~PressureForce()
{
}


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

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

    BalloonMesh *balloon = (BalloonMesh *) m_parent;
    TriangleMesh *mesh = balloon->getSurfaceP();

    mesh->invalidateTriangleNormals();
    mesh->calculateVertexNormals();

    float volume = calculateVolume();
    if(volume == 0.0f)
        volume = 1.0f;
    float pressure = m_numMoles * m_idealGasConstant * m_temperature / volume;

    float blend = pressure * 25;
    //cout << "Pressure blend: " << blend << endl;
    Color color(blend, 1.0f - blend, 0.0f);
    mesh->getMaterial(0)->setAmbient(color);
    mesh->getMaterial(0)->setDiffuse(color);

    Triangle *triangle;
    float force;
    Vector3 direction;
    PointMass *point;
    for(unsigned int i = 0; i < mesh->numTriangles(); ++i)
    {
        triangle = mesh->getTriangle(i);
        force = triangle->getArea() * pressure;

        // Vertex 1
        direction = triangle->getVertex(0)->getNormal();
        point = balloon->getPointFromVertex(triangle->getVertex(0));
        point->addForce(force * direction);

        // Vertex 2
        direction = triangle->getVertex(1)->getNormal();
        point = balloon->getPointFromVertex(triangle->getVertex(1));
        point->addForce(force * direction);

        // Vertex 3
        direction = triangle->getVertex(2)->getNormal();
        point = balloon->getPointFromVertex(triangle->getVertex(2));
        point->addForce(force * direction);
    }
}


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

float PressureForce::calculateVolume()
{
    BalloonMesh *balloon = (BalloonMesh *) m_parent;
    TriangleMesh *mesh = balloon->getSurfaceP();

    float volume = 0.0f;

    Triangle *triangle;
    for(unsigned int i = 0; i < mesh->numTriangles(); ++i)
    {
        triangle = mesh->getTriangle(i);
        const Vector3 &p1 = triangle->getVertex(0)->getPosition();
        const Vector3 &p2 = triangle->getVertex(1)->getPosition();
        const Vector3 &p3 = triangle->getVertex(2)->getPosition();

        volume += p1.dotProduct(p2.crossProduct(p3));
    }
    volume /= 6.0f;

    return volume;
}

---