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

 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 "domUtils.h"
#include "qglviewer.h" // for QGLViewer::drawAxis and Camera::drawCamera

using namespace qglviewer;
using namespace std;

#if QT_VERSION < 0x040000
// Patch for QPtrList / QList syntax difference
# define peekNext current
#endif

/*! Creates a KeyFrameInterpolator, with \p frame as associated frame().

  The frame() can be set or changed using setFrame().

  interpolationTime(), interpolationSpeed() and interpolationPeriod() are set to their default
  values. */
KeyFrameInterpolator::KeyFrameInterpolator(Frame* frame)
  : frame_(NULL), period_(40), interpolationTime_(0.0), interpolationSpeed_(1.0), interpolationStarted_(false),
    closedPath_(false), loopInterpolation_(false), pathIsValid_(false), valuesAreValid_(true), currentFrameValid_(false)
  // #CONNECTION# Values cut pasted initFromDOMElement()
{
  setFrame(frame);
#if QT_VERSION < 0x040000
  keyFrame_.setAutoDelete(true);
#endif
  for (int i=0; i<4; ++i)
#if QT_VERSION >= 0x040000
    currentFrame_[i] = new QMutableListIterator<KeyFrame*>(keyFrame_);
#else
    currentFrame_[i] = new QPtrListIterator<KeyFrame>(keyFrame_);
#endif
  connect(&timer_, SIGNAL(timeout()), SLOT(update()));
}

/*! Virtual destructor. Clears the keyFrame path. */
KeyFrameInterpolator::~KeyFrameInterpolator()
{
  deletePath();
  for (int i=0; i<4; ++i)
    delete currentFrame_[i];
}

/*! Sets the frame() associated to the KeyFrameInterpolator. */
void KeyFrameInterpolator::setFrame(Frame* const frame)
{
  if (this->frame())
    disconnect(this, SIGNAL( interpolated() ), this->frame(), SIGNAL( interpolated() ));

  frame_ = frame;

  if (this->frame())
    connect(this, SIGNAL( interpolated() ), this->frame(), SIGNAL( interpolated() ));
}

/*! Updates frame() state according to current interpolationTime(). Then adds
  interpolationPeriod()*interpolationSpeed() to interpolationTime().

  This internal method is called by a timer when interpolationIsStarted(). It can be used for
  debugging purpose. stopInterpolation() is called when interpolationTime() reaches firstTime() or
  lastTime(), unless loopInterpolation() is \c true. */
void KeyFrameInterpolator::update()
{
  interpolateAtTime(interpolationTime());

  interpolationTime_ += interpolationSpeed() * interpolationPeriod() / 1000.0;

  if (interpolationTime() > keyFrame_.last()->time())
    {
      if (loopInterpolation())
	setInterpolationTime(keyFrame_.first()->time() + interpolationTime_ - keyFrame_.last()->time());
      else
	{
	  // Make sure last KeyFrame is reached and displayed
	  interpolateAtTime(keyFrame_.last()->time());
	  stopInterpolation();
	}
      emit endReached();
    }
  else
    if (interpolationTime() < keyFrame_.first()->time())
      {
	if (loopInterpolation())
	  setInterpolationTime(keyFrame_.last()->time() - keyFrame_.first()->time() + interpolationTime_);
	else
	  {
	    // Make sure first KeyFrame is reached and displayed
	    interpolateAtTime(keyFrame_.first()->time());
	    stopInterpolation();
	  }
	emit endReached();
      }
}


/*! Starts the interpolation process.

  A timer is started with an interpolationPeriod() period that updates the frame()'s position and
  orientation. interpolationIsStarted() will return \c true until stopInterpolation() or
  toggleInterpolation() is called.

  If \p period is positive, it is set as the new interpolationPeriod(). The previous
  interpolationPeriod() is used otherwise (default).

  If interpolationTime() is larger than lastTime(), interpolationTime() is reset to firstTime()
  before interpolation starts (and inversely for negative interpolationSpeed()).

  Use setInterpolationTime() before calling this method to change the starting interpolationTime().

  See the <a href="../examples/keyFrames.html">keyFrames example</a> for an illustration.

  You may also be interested in QGLViewer::animate() and QGLViewer::startAnimation().

  \attention The keyFrames must be defined (see addKeyFrame()) \e before you startInterpolation(),
  or else the interpolation will naturally immediately stop. */
void KeyFrameInterpolator::startInterpolation(int period)
{
  if (period >= 0)
    setInterpolationPeriod(period);

  if (!keyFrame_.isEmpty())
    {
      if ((interpolationSpeed() > 0.0) && (interpolationTime() >= keyFrame_.last()->time()))
	setInterpolationTime(keyFrame_.first()->time());
      if ((interpolationSpeed() < 0.0) && (interpolationTime() <= keyFrame_.first()->time()))
	setInterpolationTime(keyFrame_.last()->time());
      timer_.start(interpolationPeriod());
      interpolationStarted_ = true;
      update();
    }
}


/*! Stops an interpolation started with startInterpolation(). See interpolationIsStarted() and toggleInterpolation(). */
void KeyFrameInterpolator::stopInterpolation()
{
  timer_.stop();
  interpolationStarted_ = false;
}


/*! Stops the interpolation and resets interpolationTime() to the firstTime().

If desired, call interpolateAtTime() after this method to actually move the frame() to
firstTime(). */
void KeyFrameInterpolator::resetInterpolation()
{
  stopInterpolation();
  setInterpolationTime(firstTime());
}

/*! Appends a new keyFrame to the path, with its associated \p time (in seconds).

  The keyFrame is given as a pointer to a Frame, which will be connected to the
  KeyFrameInterpolator: when \p frame is modified, the KeyFrameInterpolator path is updated
  accordingly. This allows for dynamic paths, where keyFrame can be edited, even during the
  interpolation. See the <a href="../examples/keyFrames.html">keyFrames example</a> for an
  illustration.

  \c NULL \p frame pointers are silently ignored. The keyFrameTime() has to be monotonously
  increasing over keyFrames.

  Use addKeyFrame(const Frame&, float) to add keyFrame by values. */
void KeyFrameInterpolator::addKeyFrame(const Frame* const frame, float time)
{
  if (!frame)
    return;

  if (keyFrame_.isEmpty())
    interpolationTime_ = time;

  if ( (!keyFrame_.isEmpty()) && (keyFrame_.last()->time() > time) )
    qWarning("Error in KeyFrameInterpolator::addKeyFrame: time is not monotone");
  else
    keyFrame_.append(new KeyFrame(frame, time));
  connect(frame, SIGNAL(modified()), SLOT(invalidateValues()));
  valuesAreValid_ = false;
  pathIsValid_ = false;
  currentFrameValid_ = false;
  resetInterpolation();
}

/*! Appends a new keyFrame to the path, with its associated \p time (in seconds).

  The path will use the current \p frame state. If you want the path to change when \p frame is
  modified, you need to pass a \e pointer to the Frame instead (see addKeyFrame(const Frame*,
  float)).

  The keyFrameTime() have to be monotonously increasing over keyFrames. */
void KeyFrameInterpolator::addKeyFrame(const Frame& frame, float time)
{
  if (keyFrame_.isEmpty())
    interpolationTime_ = time;

  if ( (!keyFrame_.isEmpty()) && (keyFrame_.last()->time() > time) )
    qWarning("Error in KeyFrameInterpolator::addKeyFrame: time is not monotone");
  else
    keyFrame_.append(new KeyFrame(frame, time));

  valuesAreValid_ = false;
  pathIsValid_ = false;
  currentFrameValid_ = false;
  resetInterpolation();
}


/*! Appends a new keyFrame to the path.

 Same as addKeyFrame(const Frame* frame, float), except that the keyFrameTime() is set to the
 previous keyFrameTime() plus one second (or 0.0 if there is no previous keyFrame). */
void KeyFrameInterpolator::addKeyFrame(const Frame* const frame)
{
  float time;
  if (keyFrame_.isEmpty())
    time = 0.0;
  else
    time = lastTime() + 1.0;

  addKeyFrame(frame, time);
}

/*! Appends a new keyFrame to the path.

 Same as addKeyFrame(const Frame& frame, float), except that the keyFrameTime() is automatically set
 to previous keyFrameTime() plus one second (or 0.0 if there is no previous keyFrame). */
void KeyFrameInterpolator::addKeyFrame(const Frame& frame)
{
  float time;
  if (keyFrame_.isEmpty())
    time = 0.0;
  else
    time = keyFrame_.last()->time() + 1.0;

  addKeyFrame(frame, time);
}

/*! Removes all keyFrames from the path. The numberOfKeyFrames() is set to 0. */
void KeyFrameInterpolator::deletePath()
{
  stopInterpolation();
#if QT_VERSION >= 0x040000
  qDeleteAll(keyFrame_);
#endif
  keyFrame_.clear();
  pathIsValid_ = false;
  valuesAreValid_ = false;
  currentFrameValid_ = false;
}

static void drawCamera(float scale)
{
  glDisable(GL_LIGHTING);

  const float halfHeight = scale * 0.07;
  const float halfWidth  = halfHeight * 1.3;
  const float dist = halfHeight / tan(M_PI/8.0);

  const float arrowHeight    = 1.5f * halfHeight;
  const float baseHeight     = 1.2f * halfHeight;
  const float arrowHalfWidth = 0.5f * halfWidth;
  const float baseHalfWidth  = 0.3f * halfWidth;

  // Frustum outline
  glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
  glBegin(GL_LINE_STRIP);
  glVertex3f(-halfWidth, halfHeight,-dist);
  glVertex3f(-halfWidth,-halfHeight,-dist);
  glVertex3f( 0.0f, 0.0f, 0.0f);
  glVertex3f( halfWidth,-halfHeight,-dist);
  glVertex3f(-halfWidth,-halfHeight,-dist);
  glEnd();
  glBegin(GL_LINE_STRIP);
  glVertex3f( halfWidth,-halfHeight,-dist);
  glVertex3f( halfWidth, halfHeight,-dist);
  glVertex3f( 0.0f, 0.0f, 0.0f);
  glVertex3f(-halfWidth, halfHeight,-dist);
  glVertex3f( halfWidth, halfHeight,-dist);
  glEnd();

  // Up arrow
  glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
  // Base
  glBegin(GL_QUADS);
  glVertex3f(-baseHalfWidth, halfHeight,-dist);
  glVertex3f( baseHalfWidth, halfHeight,-dist);
  glVertex3f( baseHalfWidth, baseHeight,-dist);
  glVertex3f(-baseHalfWidth, baseHeight,-dist);
  glEnd();

  // Arrow
  glBegin(GL_TRIANGLES);
  glVertex3f( 0.0f,           arrowHeight,-dist);
  glVertex3f(-arrowHalfWidth, baseHeight, -dist);
  glVertex3f( arrowHalfWidth, baseHeight, -dist);
  glEnd();
}

/*! Draws the path used to interpolate the frame().

  \p mask controls what is drawn: if (mask & 1) (default), the position path is drawn. If (mask &
  2), a camera representation is regularly drawn and if (mask & 4), an oriented axis is regularly
  drawn. Examples:

  \code
  drawPath();  // Simply draws the interpolation path
  drawPath(3); // Draws path and cameras
  drawPath(5); // Draws path and axis
  \endcode

  In the case where camera or axis is drawn, \p nbFrames controls the number of objects (axis or
  camera) drawn between two successive keyFrames. When \p nbFrames=1, only the path KeyFrames are
  drawn. \p nbFrames=2 also draws the intermediate orientation, etc. The maximum value is 30. \p
  nbFrames should divide 30 so that an object is drawn for each KeyFrame. Default value is 6.

  \p scale (default=1.0) controls the scaling of the camera and axis drawing. A value of
  QGLViewer::sceneRadius() should give good results.

  See the <a href="../examples/keyFrames.html">keyFrames example</a> for an illustration.

  The color of the path is the current \c glColor().

  \attention The OpenGL state is modified by this method: GL_LIGHTING is disabled and line width set
  to 2. Use this code to preserve your current OpenGL state:
  \code
  glPushAttrib(GL_ALL_ATTRIB_BITS);
  drawPathModifyGLState(mask, nbFrames, scale);
  glPopAttrib();
  \endcode */
void KeyFrameInterpolator::drawPath(int mask, int nbFrames, float scale)
{
  const int nbSteps = 30;
  if (!pathIsValid_)
    {
      path_.clear();
#if QT_VERSION < 0x040000
      path_.reserve(nbSteps*keyFrame_.count());
#endif

      if (keyFrame_.isEmpty())
	return;

      if (!valuesAreValid_)
	updateModifiedFrameValues();

      if (keyFrame_.first() == keyFrame_.last())
	path_.push_back(Frame(keyFrame_.first()->position(), keyFrame_.first()->orientation()));
      else
	{
	  static Frame fr;
	  KeyFrame* kf_[4];
	  kf_[0] = keyFrame_.first();
	  kf_[1] = kf_[0];
#if QT_VERSION >= 0x040000
	  int index = 1;
	  kf_[2] = (index < keyFrame_.size()) ? keyFrame_.at(index) : NULL;
	  index++;
	  kf_[3] = (index < keyFrame_.size()) ? keyFrame_.at(index) : NULL;
#else
	  kf_[2] = keyFrame_.next();
	  kf_[3] = keyFrame_.next();
#endif

	  while (kf_[2])
	    {
	      Vec diff = kf_[2]->position() - kf_[1]->position();
	      Vec v1 = 3.0 * diff - 2.0 * kf_[1]->tgP() - kf_[2]->tgP();
	      Vec v2 = -2.0 * diff + kf_[1]->tgP() + kf_[2]->tgP();

	      // cout << kf_[0]->time() << " , " << kf_[1]->time() << " , " << kf_[2]->time() << " , " << kf_[3]->time() << endl;
	      for (int step=0; step<nbSteps; ++step)
		{
		  float alpha = step / static_cast<float>(nbSteps);
		  fr.setPosition(kf_[1]->position() + alpha * (kf_[1]->tgP() + alpha * (v1+alpha*v2)));
		  fr.setOrientation(Quaternion::squad(kf_[1]->orientation(), kf_[1]->tgQ(), kf_[2]->tgQ(), kf_[2]->orientation(), alpha));
		  path_.push_back(fr);
		}

	      // Shift
	      kf_[0] = kf_[1];
	      kf_[1] = kf_[2];
	      kf_[2] = kf_[3];
#if QT_VERSION >= 0x040000
	      index++;
	      kf_[3] = (index < keyFrame_.size()) ? keyFrame_.at(index) : NULL;
#else
	      kf_[3] = keyFrame_.next();
#endif
	    }
	  // Add last KeyFrame
	  path_.push_back(Frame(kf_[1]->position(), kf_[1]->orientation()));
	}
      pathIsValid_ = true;
    }

  if (mask)
    {
      glDisable(GL_LIGHTING);
      glLineWidth(2);

      if (mask & 1)
	{
	  glBegin(GL_LINE_STRIP);
#if QT_VERSION >= 0x040000
	  foreach (Frame fr, path_)
	    glVertex3fv(fr.position());
#else
# if QT_VERSION < 0x030000
	  for (int i=0; i < path_.size(); ++i)
	    glVertex3fv((path_.at(i)).position());
# else
	  for (QValueVector<Frame>::const_iterator pnt=path_.begin(), end=path_.end(); pnt!=end; ++pnt)
	    glVertex3fv((*pnt).position());
# endif
#endif
	  glEnd();
	}
      if (mask & 6)
	{
	  int count = 0;
	  if (nbFrames > nbSteps)
	    nbFrames = nbSteps;
	  float goal = 0.0f;
#if QT_VERSION >= 0x040000
	  foreach (Frame fr, path_)
#else
# if QT_VERSION < 0x030000
	  for (int i=0; i < path_.size(); ++i)
# else
	  for (QValueVector<Frame>::const_iterator pnt=path_.begin(), end=path_.end(); pnt!=end; ++pnt)
# endif
#endif
	      if ((count++) >= goal)
		{
		  goal += nbSteps / static_cast<float>(nbFrames);
		  glPushMatrix();
#if QT_VERSION >= 0x040000
		  glMultMatrixd(fr.matrix());
#else
# if QT_VERSION < 0x030000
		  glMultMatrixd((path_.at(i)).matrix());
# else
		  glMultMatrixd((*pnt).matrix());
# endif
#endif
		  if (mask & 2) drawCamera(scale);
		  if (mask & 4) QGLViewer::drawAxis(scale/10.0);
		  glPopMatrix();
		}
	}
    }
}

void KeyFrameInterpolator::updateModifiedFrameValues()
{
  Quaternion prevQ = keyFrame_.first()->orientation();
  KeyFrame* kf;
#if QT_VERSION >= 0x040000
  for (int i=0; i<keyFrame_.size(); ++i)
    {
      kf = keyFrame_.at(i);
#else
  for (kf = keyFrame_.first(); kf; kf=keyFrame_.next())
    {
#endif
      if (kf->frame())
	kf->updateValuesFromPointer();
      kf->flipOrientationIfNeeded(prevQ);
      prevQ = kf->orientation();
    }

  KeyFrame* prev = keyFrame_.first();
  kf = keyFrame_.first();
#if QT_VERSION >= 0x040000
  int index = 1;
#endif
  while (kf)
    {
#if QT_VERSION >= 0x040000
      KeyFrame* next = (index < keyFrame_.size()) ? keyFrame_.at(index) : NULL;
      index++;
#else
      KeyFrame* next = keyFrame_.next();
#endif
      if (next)
	kf->computeTangent(prev, next);
      else
	kf->computeTangent(prev, kf);
      prev = kf;
      kf = next;
    }
  valuesAreValid_ = true;
}

/*! Returns the Frame associated with the keyFrame at index \p index.

 See also keyFrameTime(). \p index has to be in the range 0..numberOfKeyFrames()-1.

 \note If this keyFrame was defined using a pointer to a Frame (see addKeyFrame(const Frame*
  const)), the \e current pointed Frame state is returned. */
Frame KeyFrameInterpolator::keyFrame(int index) const
{
  const KeyFrame* const kf = keyFrame_.at(index);
  return Frame(kf->position(), kf->orientation());
}

/*! Returns the time corresponding to the \p index keyFrame.

 See also keyFrame(). \p index has to be in the range 0..numberOfKeyFrames()-1. */
float KeyFrameInterpolator::keyFrameTime(int index) const
{
  return keyFrame_.at(index)->time();
}

/*! Returns the duration of the KeyFrameInterpolator path, expressed in seconds.

 Simply corresponds to lastTime() - firstTime(). Returns 0.0 if the path has less than 2 keyFrames.
 See also keyFrameTime(). */
float KeyFrameInterpolator::duration() const
{
  return lastTime() - firstTime();
}

/*! Returns the time corresponding to the first keyFrame, expressed in seconds.

Returns 0.0 if the path is empty. See also lastTime(), duration() and keyFrameTime(). */
float KeyFrameInterpolator::firstTime() const
{
  if (keyFrame_.isEmpty())
    return 0.0;
  else
    return keyFrame_.first()->time();
}

/*! Returns the time corresponding to the last keyFrame, expressed in seconds.

Returns 0.0 if the path is empty. See also firstTime(), duration() and keyFrameTime(). */
float KeyFrameInterpolator::lastTime() const
{
  if (keyFrame_.isEmpty())
    return 0.0;
  else
    return keyFrame_.last()->time();
}

void KeyFrameInterpolator::updateCurrentKeyFrameForTime(float time)
{
  // Assertion: times are sorted in monotone order.
  // Assertion: keyFrame_ is not empty

  // TODO: Special case for loops when closed path is implemented !!
  if (!currentFrameValid_)
    // Recompute everything from scrach
#if QT_VERSION >= 0x040000
    currentFrame_[1]->toFront();
#else
    currentFrame_[1]->toFirst();
#endif

  while (currentFrame_[1]->peekNext()->time() > time)
    {
      currentFrameValid_ = false;
#if QT_VERSION >= 0x040000
      if (!currentFrame_[1]->hasPrevious())
#else
      if (currentFrame_[1]->atFirst())
#endif
	break;
#if QT_VERSION >= 0x040000
      currentFrame_[1]->previous();
#else
      --(*currentFrame_[1]);
#endif
    }

  if (!currentFrameValid_)
    *currentFrame_[2] = *currentFrame_[1];

  while (currentFrame_[2]->peekNext()->time() < time)
    {
      currentFrameValid_ = false;
#if QT_VERSION >= 0x040000
      if (!currentFrame_[2]->hasNext())
#else
      if (currentFrame_[2]->atLast())
#endif
	break;
#if QT_VERSION >= 0x040000
      currentFrame_[2]->next();
#else
      ++(*currentFrame_[2]);
#endif
    }

  if (!currentFrameValid_)
    {
      *currentFrame_[1] = *currentFrame_[2];
#if QT_VERSION >= 0x040000
      if ((currentFrame_[1]->hasPrevious()) && (time < currentFrame_[2]->peekNext()->time()))
	currentFrame_[1]->previous();
#else
      if ((!currentFrame_[1]->atFirst()) && (time < currentFrame_[2]->current()->time()))
	--(*currentFrame_[1]);
#endif

      *currentFrame_[0] = *currentFrame_[1];
#if QT_VERSION >= 0x040000
      if (currentFrame_[0]->hasPrevious())
	currentFrame_[0]->previous();
#else
      if (!currentFrame_[0]->atFirst())
	--(*currentFrame_[0]);
#endif

      *currentFrame_[3] = *currentFrame_[2];
#if QT_VERSION >= 0x040000
      if (currentFrame_[3]->hasNext())
	currentFrame_[3]->next();
#else
      if (!currentFrame_[3]->atLast())
	++(*currentFrame_[3]);
#endif

      currentFrameValid_ = true;
      splineCacheIsValid_ = false;
    }

  // cout << "Time = " << time << " : " << currentFrame_[0]->peekNext()->time() << " , " <<
  // currentFrame_[1]->peekNext()->time() << " , " << currentFrame_[2]->peekNext()->time() << " , " <<  currentFrame_[3]->peekNext()->time() << endl;
}

void KeyFrameInterpolator::updateSplineCache()
{
  Vec delta = currentFrame_[2]->peekNext()->position() - currentFrame_[1]->peekNext()->position();
  v1 = 3.0 * delta - 2.0 * currentFrame_[1]->peekNext()->tgP() - currentFrame_[2]->peekNext()->tgP();
  v2 = -2.0 * delta + currentFrame_[1]->peekNext()->tgP() + currentFrame_[2]->peekNext()->tgP();
  splineCacheIsValid_ = true;
}

/*! Interpolate frame() at time \p time (expressed in seconds). interpolationTime() is set to \p
  time and frame() is set accordingly.

  If you simply want to change interpolationTime() but not the frame() state, use
  setInterpolationTime() instead.

  Emits the interpolated() signal and makes the frame() emit the Frame::interpolated() signal. */
void KeyFrameInterpolator::interpolateAtTime(float time)
{
  setInterpolationTime(time);

  if ((keyFrame_.isEmpty()) || (!frame()))
    return;

  if (!valuesAreValid_)
    updateModifiedFrameValues();

  updateCurrentKeyFrameForTime(time);

  if (!splineCacheIsValid_)
    updateSplineCache();

  float alpha;
  float dt = currentFrame_[2]->peekNext()->time() - currentFrame_[1]->peekNext()->time();
  if (dt == 0.0)
    alpha = 0.0;
  else
    alpha = (time - currentFrame_[1]->peekNext()->time()) / dt;

  // Linear interpolation - debug
  // Vec pos = alpha*(currentFrame_[2]->peekNext()->position()) + (1.0-alpha)*(currentFrame_[1]->peekNext()->position());
  Vec pos = currentFrame_[1]->peekNext()->position() + alpha * (currentFrame_[1]->peekNext()->tgP() + alpha * (v1+alpha*v2));
  Quaternion q = Quaternion::squad(currentFrame_[1]->peekNext()->orientation(), currentFrame_[1]->peekNext()->tgQ(),
				   currentFrame_[2]->peekNext()->tgQ(), currentFrame_[2]->peekNext()->orientation(), alpha);
  frame()->setPositionAndOrientationWithConstraint(pos, q);

  emit interpolated();
}

/*! Returns an XML \c QDomElement that represents the KeyFrameInterpolator.

 The resulting QDomElement holds the KeyFrameInterpolator parameters as well as the path keyFrames
 (if the keyFrame is defined by a pointer to a Frame, use its current value).

 \p name is the name of the QDomElement tag. \p doc is the \c QDomDocument factory used to create
 QDomElement.

 Use initFromDOMElement() to restore the ManipulatedFrame state from the resulting QDomElement.

 See Vec::domElement() for a complete example. See also Quaternion::domElement(),
 Camera::domElement()...

 Note that the Camera::keyFrameInterpolator() are automatically saved by QGLViewer::saveStateToFile()
 when a QGLViewer is closed. */
QDomElement KeyFrameInterpolator::domElement(const QString& name, QDomDocument& document) const
{
  QDomElement de = document.createElement(name);
  int count = 0;
#if QT_VERSION >= 0x040000
  foreach (KeyFrame* kf, keyFrame_)
#else
  for (KeyFrame* kf = keyFrame_.first(); kf; kf = keyFrame_.next() )
#endif
    {
      Frame fr(kf->position(), kf->orientation());
      QDomElement kfNode = fr.domElement("KeyFrame", document);
      kfNode.setAttribute("index", QString::number(count));
      kfNode.setAttribute("time",  QString::number(kf->time()));
      de.appendChild(kfNode);
      ++count;
    }
  de.setAttribute("nbKF", QString::number(keyFrame_.count()));
  de.setAttribute("time", QString::number(interpolationTime()));
  de.setAttribute("speed", QString::number(interpolationSpeed()));
  de.setAttribute("period", QString::number(interpolationPeriod()));
  de.setAttribute("closedPath", (closedPath()?"true":"false"));
  de.setAttribute("loop", (loopInterpolation()?"true":"false"));
  return de;
}

/*! Restores the KeyFrameInterpolator state from a \c QDomElement created by domElement().

 Note that the frame() pointer is not included in the domElement(): you need to setFrame() after
 this method to attach a Frame to the KeyFrameInterpolator.

 See Vec::initFromDOMElement() for a complete code example.

 See also Camera::initFromDOMElement() and Frame::initFromDOMElement(). */
void KeyFrameInterpolator::initFromDOMElement(const QDomElement& element)
{
#if QT_VERSION >= 0x040000
  qDeleteAll(keyFrame_);
#endif
  keyFrame_.clear();
  QDomElement child=element.firstChild().toElement();
  while (!child.isNull())
    {
      if (child.tagName() == "KeyFrame")
	{
	  Frame fr;
	  fr.initFromDOMElement(child);
	  float time = DomUtils::floatFromDom(child, "time", 0.0);
	  addKeyFrame(fr, time);
	}

      child = child.nextSibling().toElement();
    }

  // #CONNECTION# Values cut pasted from constructor
  setInterpolationTime(DomUtils::floatFromDom(element, "time", 0.0));
  setInterpolationSpeed(DomUtils::floatFromDom(element, "speed", 1.0));
  setInterpolationPeriod(DomUtils::intFromDom(element, "period", 40));
  setClosedPath(DomUtils::boolFromDom(element, "closedPath", false));
  setLoopInterpolation(DomUtils::boolFromDom(element, "loop", false));

  // setFrame(NULL);
  pathIsValid_ = false;
  valuesAreValid_ = false;
  currentFrameValid_ = false;

  stopInterpolation();
}

#ifndef DOXYGEN

//////////// KeyFrame private class implementation /////////
KeyFrameInterpolator::KeyFrame::KeyFrame(const Frame& fr, float t)
  : time_(t), frame_(NULL)
{
  p_ = fr.position();
  q_ = fr.orientation();
}

KeyFrameInterpolator::KeyFrame::KeyFrame(const Frame* fr, float t)
  : time_(t), frame_(fr)
{
  updateValuesFromPointer();
}

void KeyFrameInterpolator::KeyFrame::updateValuesFromPointer()
{
  p_ = frame()->position();
  q_ = frame()->orientation();
}

void KeyFrameInterpolator::KeyFrame::computeTangent(const KeyFrame* const prev, const KeyFrame* const next)
{
  tgP_ = 0.5 * (next->position() - prev->position());
  tgQ_ = Quaternion::squadTangent(prev->orientation(), q_, next->orientation());
}

void KeyFrameInterpolator::KeyFrame::flipOrientationIfNeeded(const Quaternion& prev)
{
  if (Quaternion::dot(prev, q_) < 0.0)
    q_.negate();
}

#endif //DOXYGEN