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

using namespace std;


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

/*
Triangle::Triangle()
: m_normalValid(false)
{
    m_vertices[0] = 0;
    m_vertices[1] = 0;
    m_vertices[2] = 0;
}
*/

Triangle::Triangle(Vertex *a, Vertex *b, Vertex *c)
: m_normalValid(false), m_material(0)
{
    m_vertices[0] = a;
    m_vertices[1] = b;
    m_vertices[2] = c;
}

Triangle::~Triangle()
{
}


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

const Vector3 &Triangle::getNormal()
{
    if(!m_normalValid)
        calculateNormal();

    return m_normal;
}


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

void Triangle::calculateNormal()
{
    Vector3 leg1 = m_vertices[1]->getPosition() - m_vertices[0]->getPosition();
    Vector3 leg2 = m_vertices[2]->getPosition() - m_vertices[0]->getPosition();
    m_normal = (leg1).crossProduct(leg2);

    m_normal.normalize(); 
    m_normalValid = true;
}

float Triangle::getArea() const
{
    const Vector3 &v1 = m_vertices[0]->getPosition();
    const Vector3 &v2 = m_vertices[1]->getPosition();
    const Vector3 &v3 = m_vertices[2]->getPosition();

    return 0.5f * ((v1 - v3).crossProduct(v2 - v3)).length();
    //return 0.5f * (v1.crossProduct(v2) + v2.crossProduct(v3) + v3.crossProduct(v1)).length();
/*
    float a = m_vertices[0]->getPosition().distance(m_vertices[1]->getPosition());
    float b = m_vertices[1]->getPosition().distance(m_vertices[2]->getPosition());
    float c = m_vertices[2]->getPosition().distance(m_vertices[0]->getPosition());

    float s = (a + b + c) / 2.0f;
    return sqrtf(s * (s - a) * (s - b) * (s - c));
*/
}

Vector3 Triangle::getMidpoint() const
{
    const Vector3 &p1 = m_vertices[0]->getPosition();
    const Vector3 &p2 = m_vertices[1]->getPosition();
    const Vector3 &p3 = m_vertices[2]->getPosition();

    return ((p1 + p2 + p3) / 3.0f);
}


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

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