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

 Copyright (C) 2002-2014 Gilles Debunne. All rights reserved.

 This file is part of the QGLViewer library version 2.6.3.

 http://www.libqglviewer.com - contact@libqglviewer.com

 This file may be used under the terms of the GNU General Public License 
 versions 2.0 or 3.0 as published by the Free Software Foundation and
 appearing in the LICENSE file included in the packaging of this file.
 In addition, as a special exception, Gilles Debunne gives you certain 
 additional rights, described in the file GPL_EXCEPTION in this package.

 libQGLViewer uses dual licensing. Commercial/proprietary software must
 purchase a libQGLViewer Commercial License.

 This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

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

#ifndef QGLVIEWER_KEY_FRAME_INTERPOLATOR_H
#define QGLVIEWER_KEY_FRAME_INTERPOLATOR_H

#include <QObject>
#include <QTimer>

#include "quaternion.h"
// Not actually needed, but some bad compilers (Microsoft VS6) complain.
#include "frame.h"

// If you compiler complains about incomplete type, uncomment the next line
// #include "frame.h"
// and comment "class Frame;" 3 lines below

namespace qglviewer {
class Camera;
class Frame;
/*! \brief A keyFrame Catmull-Rom Frame interpolator.
  \class KeyFrameInterpolator keyFrameInterpolator.h QGLViewer/keyFrameInterpolator.h

  A KeyFrameInterpolator holds keyFrames (that define a path) and a pointer to a Frame of your
  application (which will be interpolated). When the user startInterpolation(), the
  KeyFrameInterpolator regularly updates the frame() position and orientation along the path.

  Here is a typical utilization example (see also the <a href="../examples/keyFrames.html">keyFrames
  example</a>):
  \code


  init()
  {
	// The KeyFrameInterpolator kfi is given the Frame that it will drive over time.
	kfi = new KeyFrameInterpolator( new Frame() );
	kfi->addKeyFrame( Frame( Vec(1,0,0), Quaternion() ) );
	kfi->addKeyFrame( new Frame( Vec(2,1,0), Quaternion() ) );
	// ...and so on for all the keyFrames.

	// Ask for a display update after each update of the KeyFrameInterpolator
	connect(kfi, SIGNAL(interpolated()), SLOT(update()));

	kfi->startInterpolation();
  }

  draw()
  {
	glPushMatrix();
	glMultMatrixd( kfi->frame()->matrix() );
	// Draw your object here. Its position and orientation are interpolated.
	glPopMatrix();
  }
  \endcode

  The keyFrames are defined by a Frame and a time, expressed in seconds. The Frame can be provided
  as a const reference or as a pointer to a Frame (see the addKeyFrame() methods). In the latter
  case, the path will automatically be updated when the Frame is modified (using the
  Frame::modified() signal).

  The time has to be monotonously increasing over keyFrames. When interpolationSpeed() equals 1.0
  (default value), these times correspond to actual user's seconds during interpolation (provided
  that your main loop is fast enough). The interpolation is then real-time: the keyFrames will be
  reached at their keyFrameTime().

  <h3>Interpolation details</h3>

  When the user startInterpolation(), a timer is started which will update the frame()'s position
  and orientation every interpolationPeriod() milliseconds. This update increases the
  interpolationTime() by interpolationPeriod() * interpolationSpeed() milliseconds.

  Note that this mechanism ensures that the number of interpolation steps is constant and equal to
  the total path duration() divided by the interpolationPeriod() * interpolationSpeed(). This is
  especially useful for benchmarking or movie creation (constant number of snapshots).

  During the interpolation, the KeyFrameInterpolator emits an interpolated() signal, which will
  usually be connected to the QGLViewer::update() slot. The interpolation is stopped when
  interpolationTime() is greater than the lastTime() (unless loopInterpolation() is \c true) and the
  endReached() signal is then emitted.

  Note that a Camera has Camera::keyFrameInterpolator(), that can be used to drive the Camera along a
  path, or to restore a saved position (a path made of a single keyFrame). Press Alt+Fx to define a
  new keyFrame for path x. Pressing Fx plays/pauses path interpolation. See QGLViewer::pathKey() and
  the <a href="../keyboard.html">keyboard page</a> for details.

  \attention If a Constraint is attached to the frame() (see Frame::constraint()), it should be
  deactivated before interpolationIsStarted(), otherwise the interpolated motion (computed as if
  there was no constraint) will probably be erroneous.

  <h3>Retrieving interpolated values</h3>

  This code defines a KeyFrameInterpolator, and displays the positions that will be followed by the
  frame() along the path:
  \code
  KeyFrameInterpolator kfi( new Frame() );
  // calls to kfi.addKeyFrame() to define the path.

  const qreal deltaTime = 0.04; // output a position every deltaTime seconds
  for (qreal time=kfi.firstTime(); time<=kfi.lastTime(); time += deltaTime)
  {
	kfi.interpolateAtTime(time);
	cout << "t=" << time << "\tpos=" << kfi.frame()->position() << endl;
  }
  \endcode
  You may want to temporally disconnect the \c kfi interpolated() signal from the
  QGLViewer::update() slot before calling this code. \nosubgrouping */
class QGLVIEWER_EXPORT KeyFrameInterpolator : public QObject
{
	// todo closedPath, insertKeyFrames, deleteKeyFrame, replaceKeyFrame
	Q_OBJECT

public:
	KeyFrameInterpolator(Frame* fr=NULL);
	virtual ~KeyFrameInterpolator();

Q_SIGNALS:
	/*! This signal is emitted whenever the frame() state is interpolated.

	The emission of this signal triggers the synchronous emission of the frame()
	Frame::interpolated() signal, which may also be useful.

	This signal should especially be connected to your QGLViewer::update() slot, so that the display
	is updated after every update of the KeyFrameInterpolator frame():
	\code
	connect(myKeyFrameInterpolator, SIGNAL(interpolated()), SLOT(update()));
	\endcode
	Use the QGLViewer::QGLViewerPool() to connect the signal to all the viewers.

	Note that the QGLViewer::camera() Camera::keyFrameInterpolator() created using QGLViewer::pathKey()
	have their interpolated() signals automatically connected to the QGLViewer::update() slot. */
	void interpolated();

	/*! This signal is emitted when the interpolation reaches the first (when interpolationSpeed()
	  is negative) or the last keyFrame.

	When loopInterpolation() is \c true, interpolationTime() is reset and the interpolation
	continues. It otherwise stops. */
	void endReached();

	/*! @name Path creation */
	//@{
public Q_SLOTS:
	void addKeyFrame(const Frame& frame);
	void addKeyFrame(const Frame& frame, qreal time);

	void addKeyFrame(const Frame* const frame);
	void addKeyFrame(const Frame* const frame, qreal time);

	void deletePath();
	//@}

	/*! @name Associated Frame */
	//@{
public:
	/*! Returns the associated Frame and that is interpolated by the KeyFrameInterpolator.

	When interpolationIsStarted(), this Frame's position and orientation will regularly be updated
	by a timer, so that they follow the KeyFrameInterpolator path.

	Set using setFrame() or with the KeyFrameInterpolator constructor. */
	Frame* frame() const { return frame_; }

public Q_SLOTS:
	void setFrame(Frame* const frame);
	//@}

	/*! @name Path parameters */
	//@{
public:
	Frame keyFrame(int index) const;
	qreal keyFrameTime(int index) const;
	/*! Returns the number of keyFrames used by the interpolation. Use addKeyFrame() to add new keyFrames. */
	int numberOfKeyFrames() const { return keyFrame_.count(); }
	qreal duration() const;
	qreal firstTime() const;
	qreal lastTime() const;
	//@}

	/*! @name Interpolation parameters */
	//@{
public:
	/*! Returns the current interpolation time (in seconds) along the KeyFrameInterpolator path.

	This time is regularly updated when interpolationIsStarted(). Can be set directly with
	setInterpolationTime() or interpolateAtTime(). */
	qreal interpolationTime() const { return interpolationTime_; }
	/*! Returns the current interpolation speed.

	Default value is 1.0, which means keyFrameTime() will be matched during the interpolation
	(provided that your main loop is fast enough).

	A negative value will result in a reverse interpolation of the keyFrames. See also
	interpolationPeriod(). */
	qreal interpolationSpeed() const { return interpolationSpeed_; }
	/*! Returns the current interpolation period, expressed in milliseconds.

	The update of the frame() state will be done by a timer at this period when
	interpolationIsStarted().

	This period (multiplied by interpolationSpeed()) is added to the interpolationTime() at each
	update, and the frame() state is modified accordingly (see interpolateAtTime()). Default value
	is 40 milliseconds. */
	int interpolationPeriod() const { return period_; }
	/*! Returns \c true when the interpolation is played in an infinite loop.

	When \c false (default), the interpolation stops when interpolationTime() reaches firstTime()
	(with negative interpolationSpeed()) or lastTime().

	interpolationTime() is otherwise reset to firstTime() (+ interpolationTime() - lastTime()) (and
	inversely for negative interpolationSpeed()) and interpolation continues.

	In both cases, the endReached() signal is emitted. */
	bool loopInterpolation() const { return loopInterpolation_; }
#ifndef DOXYGEN
	/*! Whether or not (default) the path defined by the keyFrames is a closed loop. When \c true,
	the last and the first KeyFrame are linked by a new spline segment.

	Use setLoopInterpolation() to create a continuous animation over the entire path.
	\attention The closed path feature is not yet implemented. */
	bool closedPath() const { return closedPath_; }
#endif
public Q_SLOTS:
	/*! Sets the interpolationTime().

	\attention The frame() state is not affected by this method. Use this function to define the
	starting time of a future interpolation (see startInterpolation()). Use interpolateAtTime() to
	actually interpolate at a given time. */
	void setInterpolationTime(qreal time) { interpolationTime_ = time; }
	/*! Sets the interpolationSpeed(). Negative or null values are allowed. */
	void setInterpolationSpeed(qreal speed) { interpolationSpeed_ = speed; }
	/*! Sets the interpolationPeriod(). */
	void setInterpolationPeriod(int period) { period_ = period; }
	/*! Sets the loopInterpolation() value. */
	void setLoopInterpolation(bool loop=true) { loopInterpolation_ = loop; }
#ifndef DOXYGEN
	/*! Sets the closedPath() value. \attention The closed path feature is not yet implemented. */
	void setClosedPath(bool closed=true) { closedPath_ = closed; }
#endif
	//@}


	/*! @name Interpolation */
	//@{
public:
	/*! Returns \c true when the interpolation is being performed. Use startInterpolation(),
	stopInterpolation() or toggleInterpolation() to modify this state. */
	bool interpolationIsStarted() const { return interpolationStarted_; }
public Q_SLOTS:
	void startInterpolation(int period = -1);
	void stopInterpolation();
	void resetInterpolation();
	/*! Calls startInterpolation() or stopInterpolation(), depending on interpolationIsStarted(). */
	void toggleInterpolation() { if (interpolationIsStarted()) stopInterpolation(); else startInterpolation(); }
	virtual void interpolateAtTime(qreal time);
	//@}

	/*! @name Path drawing */
	//@{
public:
	virtual void drawPath(int mask=1, int nbFrames=6, qreal scale=1.0);
	//@}

	/*! @name XML representation */
	//@{
public:
	virtual QDomElement domElement(const QString& name, QDomDocument& document) const;
	virtual void initFromDOMElement(const QDomElement& element);
	//@}

private Q_SLOTS:
	virtual void update();
	virtual void invalidateValues() { valuesAreValid_ = false; pathIsValid_ = false; splineCacheIsValid_ = false; }

private:
	// Copy constructor and opertor= are declared private and undefined
	// Prevents everyone from trying to use them
	// KeyFrameInterpolator(const KeyFrameInterpolator& kfi);
	// KeyFrameInterpolator& operator=(const KeyFrameInterpolator& kfi);

	void updateCurrentKeyFrameForTime(qreal time);
	void updateModifiedFrameValues();
	void updateSplineCache();

#ifndef DOXYGEN
	// Internal private KeyFrame representation
	class KeyFrame
	{
	public:
		KeyFrame(const Frame& fr, qreal t);
		KeyFrame(const Frame* fr, qreal t);

		Vec position() const { return p_; }
		Quaternion orientation() const { return q_; }
		Vec tgP() const { return tgP_; }
		Quaternion tgQ() const { return tgQ_; }
		qreal time() const { return time_; }
		const Frame* frame() const { return frame_; }
		void updateValuesFromPointer();
		void flipOrientationIfNeeded(const Quaternion& prev);
		void computeTangent(const KeyFrame* const prev, const KeyFrame* const next);
	private:
		Vec p_, tgP_;
		Quaternion q_, tgQ_;
		qreal time_;
		const Frame* const frame_;
	};
#endif

	// K e y F r a m e s
	mutable QList<KeyFrame*> keyFrame_;
	QMutableListIterator<KeyFrame*>* currentFrame_[4];
	QList<Frame> path_;

	// A s s o c i a t e d   f r a m e
	Frame* frame_;

	// R h y t h m
	QTimer timer_;
	int period_;
	qreal interpolationTime_;
	qreal interpolationSpeed_;
	bool interpolationStarted_;

	// M i s c
	bool closedPath_;
	bool loopInterpolation_;

	// C a c h e d   v a l u e s   a n d   f l a g s
	bool pathIsValid_;
	bool valuesAreValid_;
	bool currentFrameValid_;
	bool splineCacheIsValid_;
	Vec v1, v2;
};

} // namespace qglviewer

#endif // QGLVIEWER_KEY_FRAME_INTERPOLATOR_H
