/****************************************************************************

 Copyright (C) 2002-2006 Gilles Debunne (Gilles.Debunne@imag.fr)

This file is part of the QGLViewer library.
 Version 2.2.4-1, released on December 12, 2006.

 http://artis.imag.fr/Members/Gilles.Debunne/QGLViewer

 libQGLViewer is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2 of the License, or
 (at your option) any later version.

 libQGLViewer 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 General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with libQGLViewer; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

*****************************************************************************/

#include "animation.h"
#include <math.h>
#include <stdlib.h> // RAND_MAX

using namespace qglviewer;
using namespace std;

///////////////////////   V i e w e r  ///////////////////////
void Viewer::init()
{
  restoreStateFromFile();
  glDisable(GL_LIGHTING);
  nbPart_ = 2000;
  particle_ = new Particle[nbPart_];
  glPointSize(3.0);
  setGridIsDrawn();
  help();
  startAnimation();
}

void Viewer::draw()
{
  glBegin(GL_POINTS);
  for (int i=0; i<nbPart_; i++)
    particle_[i].draw();
  glEnd();
}

void Viewer::animate()
{
  for (int i=0; i<nbPart_; i++)
    particle_[i].animate();
}

QString Viewer::helpString() const
{
  QString text("<h2>A n i m a t i o n</h2>");
  text += "Use the <i>animate()</i> function to implement the animation part of your ";
  text += "application. Once the animation is started, <i>animate()</i> and <i>draw()</i> ";
  text += "are called in an infinite loop, at a frequency that can be fixed.<br><br>";
  text += "Press <b>Return</b> to start/stop the animation.";
  return text;
}

///////////////////////   P a r t i c l e   ///////////////////////////////

Particle::Particle()
{
  init();
}

void Particle::animate()
{
  speed_.z -= 0.05;
  pos_     += 0.1 * speed_;

  if (pos_.z < 0.0)
    {
      speed_.z = -0.8*speed_.z;
      pos_.z = 0.0;
    }

  if (++age_ == ageMax_)
    init();
}

void Particle::draw()
{
  glColor3f(age_/(float)ageMax_, age_/(float)ageMax_, 1.0);
  glVertex3fv(pos_);
}


void Particle::init()
{
  pos_ = Vec(0.0, 0.0, 0.0);
  float angle = 2.0 * M_PI * rand() / RAND_MAX;
  float norm  = 0.04 * rand() / RAND_MAX;
  speed_ = Vec(norm*cos(angle), norm*sin(angle), rand() / static_cast<float>(RAND_MAX) );
  age_ = 0;
  ageMax_ = 50 + static_cast<int>(100.0 * rand() / RAND_MAX);
}