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// goto_hermite.cc
// nono - programme du robot 2004. {{{
//
// Copyright (C) 2004 Nicolas Schodet
//
// Robot APB Team/Efrei 2004.
//        Web: http://assos.efrei.fr/robot/
//      Email: robot AT efrei DOT fr
//
// This program 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.
// 
// This program 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 this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
// }}}
#include "goto_hermite.h"

#include <iostream>

/// Constructeur.
/// fa : angle final.
GotoHermite::GotoHermite (double fa)
    : step_ (0.0), lastDist_ (0.0), ia_ (0.0), fa_ (fa),
      di_ (defaultDi_), df_ (defaultDf_)
{
    points_.push_back (Point ());
}

/// Constructeur.
/// fa : angle final.
/// di : longueur de la tangente initiale.
/// df : longueur de la tangente finale.
GotoHermite::GotoHermite (double fa, double di, double df)
    : step_ (0.0), lastDist_ (0.0), ia_ (0.0), fa_ (fa), di_ (di), df_ (df)
{
    points_.push_back (Point ());
}

/// Ajoute un point au chemin.
void
GotoHermite::add (double x, double y)
{
    Point newPoint (x, y);
    // Met � jour le tableau des distances.
    double dist = newPoint.distTo (points_.back ());
    for (Dists::iterator i = dists_.begin ();
	 i != dists_.end ();
	 ++i)
      {
	*i += dist;
      }
    dists_.push_back (0.0);
    lastDist_ += dist;
    // Ajoute le point.
    points_.push_back (newPoint);
}

/// Initialise le Goto, appel� au d�but de la trajectoire.
void
GotoHermite::init (const Tracker &t)
{
    double x, y, a;
    t.getPos (x, y, a);
    lastPoint_ = points_[0] = Point (x, y);
    ia_ = a;
}

/// Fournit la distance au point final (mm), le point le plus loin � moins
/// de distmax (mm) et renvois false si le Goto est fini.
/// eps : distance (mm) en dessous de laquelle on consid�re que la destination
/// est atteinte.
/// distmax : distance (mm) maximale du point.
/// dist : distance (mm) au point final.
/// (x, y) : point interm�diaire (mm).
bool
GotoHermite::get (const Tracker &t, double distmax, double eps, double &dist,
		  double &x, double &y)
{
    Point cur (t.getX (), t.getY ());
    // Trouve le point interm�diaire.
    double sqDistMax = distmax * distmax;
    while (cur.sqDistTo (lastPoint_) < sqDistMax)
      {
	step_ += stepSize_;
	if (!computePoint (step_, lastPoint_, lastDist_))
	    break;
      }
    // Trouve la distance au point final.
    dist = lastDist_ + cur.distTo (lastPoint_);
    if (eps > dist)
	return false;
    x = lastPoint_.x;
    y = lastPoint_.y;
    return true;
}

/// Test le GotoHermite en affichant la liste des points g�n�r�s.
void
GotoHermite::test (std::ostream &os) const
{
    Point p;
    double dist;
    for (double s = 0.0; ; s += stepSize_)
      {
	if (!computePoint (s, p, dist))
	    break;
	std::cout << p << ' ' << dist << std::endl;
      }
}

/// Calcule le point au pas step et la distance restant � parcourir,
/// renvois faux si fini.
bool
GotoHermite::computePoint (double step, Point &p, double &dist) const
{
    // V�rifications d'overflow.
    if (step < 0.0)
	step = 0.0;
    // D�termine la section correspondante.
    int i = static_cast<int> (step);
    if (i >= static_cast<int> (points_.size ()) - 1)
	return false;
    step -= i;
    const Point &p1 = points_[i];
    const Point &p2 = points_[i + 1];
    // Calcule les fonction d'hermite.
    double step2 = step * step;
    double step3 = step2 * step;
    double h2 = -2 * step3 + 3 * step2;
    double h1 = -h2 + 1;
    double h3 = step3 - 2 * step2 + step;
    double h4 = step3 - step2;
    // Calcule les tangeantes.
    Point t1;
    if (i > 0)
      {
	// M�thode de Catmull-Rom.
	t1 = (p2 - points_[i - 1]) * tightness_;
      }
    else
      {
	t1 = p1;
	t1.x = cos (ia_) * di_;
	t1.y = sin (ia_) * di_;
      }
    Point t2;
    if (i < static_cast<int> (points_.size ()) - 2)
      {
	// M�thode de Catmull-Rom.
	t2 = (points_[i + 2] - p1) * tightness_;
      }
    else
      {
	t2 = p2;
	t2.x = cos (fa_) * df_;
	t2.y = sin (fa_) * df_;
      }
    // Applique Hermite.
    t1 *= h3;
    t2 *= h4;
    p = p1 * h1;
    p += t1;
    p += t2;
    p += p2 * h2;
    // Calcule la distance au point final.
    dist = dists_[i] + p.distTo (points_[i + 1]);
    return true;
}