A keyFrame Catmull-Rom Frame interpolator. More...

#include <QGLViewer/keyFrameInterpolator.h>

Inheritance diagram for qglviewer::KeyFrameInterpolator:

Classes
class	KeyFrame

Signals
void	endReached ()

void	interpolated ()

Public Member Functions
	KeyFrameInterpolator (Frame *fr=NULL)

virtual	~KeyFrameInterpolator ()

Private Slots
virtual void	invalidateValues ()

virtual void	update ()

Private Member Functions
void	updateCurrentKeyFrameForTime (qreal time)

void	updateModifiedFrameValues ()

void	updateSplineCache ()

Private Attributes
bool	closedPath_

QMutableListIterator< KeyFrame * > *	currentFrame_ [4]

bool	currentFrameValid_

Frame *	frame_

qreal	interpolationSpeed_

bool	interpolationStarted_

qreal	interpolationTime_

QList< KeyFrame * >	keyFrame_

bool	loopInterpolation_

QList< Frame >	path_

bool	pathIsValid_

int	period_

bool	splineCacheIsValid_

QTimer	timer_

Vec	v1

Vec	v2

bool	valuesAreValid_

Path creation
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 ()

Associated Frame
Frame *	frame () const

void	setFrame (Frame *const frame)

Path parameters
Frame	keyFrame (int index) const

qreal	keyFrameTime (int index) const

int	numberOfKeyFrames () const

qreal	duration () const

qreal	firstTime () const

qreal	lastTime () const

Interpolation parameters
qreal	interpolationTime () const

qreal	interpolationSpeed () const

int	interpolationPeriod () const

bool	loopInterpolation () const

bool	closedPath () const

void	setInterpolationTime (qreal time)

void	setInterpolationSpeed (qreal speed)

void	setInterpolationPeriod (int period)

void	setLoopInterpolation (bool loop=true)

void	setClosedPath (bool closed=true)

Interpolation
bool	interpolationIsStarted () const

void	startInterpolation (int period=-1)

void	stopInterpolation ()

void	resetInterpolation ()

void	toggleInterpolation ()

virtual void	interpolateAtTime (qreal time)

Path drawing
virtual void	drawPath (int mask=1, int nbFrames=6, qreal scale=1.0)

XML representation
virtual QDomElement	domElement (const QString &name, QDomDocument &document) const

virtual void	initFromDOMElement (const QDomElement &element)

Detailed Description

A keyFrame Catmull-Rom Frame interpolator.

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 keyFrames example):

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();
}

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().

Interpolation details

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 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 keyboard page 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.

Retrieving interpolated values

This code defines a KeyFrameInterpolator, and displays the positions that will be followed by the frame() along the path:

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;
}

You may want to temporally disconnect the kfi interpolated() signal from the QGLViewer::update() slot before calling this code.

Definition at line 126 of file keyFrameInterpolator.h.

Constructor & Destructor Documentation

KeyFrameInterpolator::KeyFrameInterpolator ( Frame * frame = NULL )

Creates a KeyFrameInterpolator, with frame as associated frame().

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

interpolationTime(), interpolationSpeed() and interpolationPeriod() are set to their default values.

Definition at line 35 of file keyFrameInterpolator.cpp.

KeyFrameInterpolator::~KeyFrameInterpolator ( )

virtual

Virtual destructor. Clears the keyFrame path.

Definition at line 47 of file keyFrameInterpolator.cpp.

Member Function Documentation

void KeyFrameInterpolator::addKeyFrame ( const Frame & frame )

slot

Appends a new keyFrame to the path.

Same as addKeyFrame(const Frame& frame, qreal), except that the keyFrameTime() is automatically set to previous keyFrameTime() plus one second (or 0.0 if there is no previous keyFrame).

Definition at line 236 of file keyFrameInterpolator.cpp.

void KeyFrameInterpolator::addKeyFrame	(	const Frame &	frame,
		qreal	time
	)

slot

Appends a new keyFrame to the path, with its associated time (in seconds).

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

The keyFrameTime() have to be monotonously increasing over keyFrames.

Definition at line 200 of file keyFrameInterpolator.cpp.

void KeyFrameInterpolator::addKeyFrame ( const Frame *const frame )

slot

Appends a new keyFrame to the path.

Same as addKeyFrame(const Frame* frame, qreal), except that the keyFrameTime() is set to the previous keyFrameTime() plus one second (or 0.0 if there is no previous keyFrame).

Definition at line 221 of file keyFrameInterpolator.cpp.

void KeyFrameInterpolator::addKeyFrame	(	const Frame *const	frame,
		qreal	time
	)

slot

Appends a new keyFrame to the path, with its associated time (in seconds).

The keyFrame is given as a pointer to a Frame, which will be connected to the KeyFrameInterpolator: when 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 keyFrames example for an illustration.

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

Use addKeyFrame(const Frame&, qreal) to add keyFrame by values.

Definition at line 174 of file keyFrameInterpolator.cpp.

bool qglviewer::KeyFrameInterpolator::closedPath ( ) const

inline

Whether or not (default) the path defined by the keyFrames is a closed loop. When 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.

Definition at line 239 of file keyFrameInterpolator.h.

void KeyFrameInterpolator::deletePath ( )

slot

Removes all keyFrames from the path. The numberOfKeyFrames() is set to 0.

Definition at line 248 of file keyFrameInterpolator.cpp.

QDomElement KeyFrameInterpolator::domElement	(	const QString &	name,
		QDomDocument &	document
	)		const

virtual

Returns an XML 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).

name is the name of the QDomElement tag. doc is the 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.

Definition at line 617 of file keyFrameInterpolator.cpp.

void KeyFrameInterpolator::drawPath	(	int	mask = `1`,
		int	nbFrames = `6`,
		qreal	scale = `1.0`
	)

virtual

Draws the path used to interpolate the frame().

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:

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

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

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

See the keyFrames example for an illustration.

The color of the path is the current 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:
glPushAttrib(GL_ALL_ATTRIB_BITS);
drawPathModifyGLState(mask, nbFrames, scale);
glPopAttrib();

Definition at line 337 of file keyFrameInterpolator.cpp.

qreal KeyFrameInterpolator::duration ( ) const

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().

Definition at line 477 of file keyFrameInterpolator.cpp.

void qglviewer::KeyFrameInterpolator::endReached ( )

signal

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

When loopInterpolation() is true, interpolationTime() is reset and the interpolation continues. It otherwise stops.

qreal KeyFrameInterpolator::firstTime ( ) const

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().

Definition at line 485 of file keyFrameInterpolator.cpp.

Frame* qglviewer::KeyFrameInterpolator::frame ( ) const

inline

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.

Definition at line 180 of file keyFrameInterpolator.h.

void KeyFrameInterpolator::initFromDOMElement ( const QDomElement & element )

virtual

Restores the KeyFrameInterpolator state from a 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.

Definition at line 647 of file keyFrameInterpolator.cpp.

void KeyFrameInterpolator::interpolateAtTime ( qreal time )

virtualslot

Interpolate frame() at time time (expressed in seconds). interpolationTime() is set to 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.

Definition at line 570 of file keyFrameInterpolator.cpp.

void qglviewer::KeyFrameInterpolator::interpolated ( )

signal

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():

connect(myKeyFrameInterpolator, SIGNAL(interpolated()), SLOT(update()));

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.

bool qglviewer::KeyFrameInterpolator::interpolationIsStarted ( ) const

inline

Returns true when the interpolation is being performed. Use startInterpolation(), stopInterpolation() or toggleInterpolation() to modify this state.

Definition at line 266 of file keyFrameInterpolator.h.

int qglviewer::KeyFrameInterpolator::interpolationPeriod ( ) const

inline

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.

Definition at line 222 of file keyFrameInterpolator.h.

qreal qglviewer::KeyFrameInterpolator::interpolationSpeed ( ) const

inline

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().

Definition at line 213 of file keyFrameInterpolator.h.

qreal qglviewer::KeyFrameInterpolator::interpolationTime ( ) const

inline

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().

Definition at line 205 of file keyFrameInterpolator.h.

virtual void qglviewer::KeyFrameInterpolator::invalidateValues ( )

inlineprivatevirtualslot

Definition at line 291 of file keyFrameInterpolator.h.

Frame KeyFrameInterpolator::keyFrame ( int index ) const

Returns the Frame associated with the keyFrame at index index.

See also keyFrameTime(). 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 current pointed Frame state is returned.

Definition at line 459 of file keyFrameInterpolator.cpp.

qreal KeyFrameInterpolator::keyFrameTime ( int index ) const

Returns the time corresponding to the index keyFrame.

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

Definition at line 468 of file keyFrameInterpolator.cpp.

qreal KeyFrameInterpolator::lastTime ( ) const

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().

Definition at line 496 of file keyFrameInterpolator.cpp.

bool qglviewer::KeyFrameInterpolator::loopInterpolation ( ) const

inline

Returns true when the interpolation is played in an infinite loop.

When 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.

Definition at line 232 of file keyFrameInterpolator.h.

int qglviewer::KeyFrameInterpolator::numberOfKeyFrames ( ) const

inline

Returns the number of keyFrames used by the interpolation. Use addKeyFrame() to add new keyFrames.

Definition at line 192 of file keyFrameInterpolator.h.

void KeyFrameInterpolator::resetInterpolation ( )

slot

Stops the interpolation and resets interpolationTime() to the firstTime().

If desired, call interpolateAtTime() after this method to actually move the frame() to firstTime().

Definition at line 156 of file keyFrameInterpolator.cpp.

void qglviewer::KeyFrameInterpolator::setClosedPath ( bool closed = true )

inlineslot

Sets the closedPath() value.

Attention: The closed path feature is not yet implemented.

Definition at line 256 of file keyFrameInterpolator.h.

void KeyFrameInterpolator::setFrame ( Frame *const frame )

slot

Sets the frame() associated to the KeyFrameInterpolator.

Definition at line 55 of file keyFrameInterpolator.cpp.

void qglviewer::KeyFrameInterpolator::setInterpolationPeriod ( int period )

inlineslot

Sets the interpolationPeriod().

Definition at line 251 of file keyFrameInterpolator.h.

void qglviewer::KeyFrameInterpolator::setInterpolationSpeed ( qreal speed )

inlineslot

Sets the interpolationSpeed(). Negative or null values are allowed.

Definition at line 249 of file keyFrameInterpolator.h.

void qglviewer::KeyFrameInterpolator::setInterpolationTime ( qreal time )

inlineslot

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.

Definition at line 247 of file keyFrameInterpolator.h.

void qglviewer::KeyFrameInterpolator::setLoopInterpolation ( bool loop = true )

inlineslot

Sets the loopInterpolation() value.

Definition at line 253 of file keyFrameInterpolator.h.

void KeyFrameInterpolator::startInterpolation ( int period = -1 )

slot

Starts the interpolation process.

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

If 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 keyFrames example for an illustration.

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

Attention: The keyFrames must be defined (see addKeyFrame()) before you startInterpolation(), or else the interpolation will naturally immediately stop.

Definition at line 126 of file keyFrameInterpolator.cpp.

void KeyFrameInterpolator::stopInterpolation ( )

slot

Stops an interpolation started with startInterpolation(). See interpolationIsStarted() and toggleInterpolation().

Definition at line 145 of file keyFrameInterpolator.cpp.

void qglviewer::KeyFrameInterpolator::toggleInterpolation ( )

inlineslot

Calls startInterpolation() or stopInterpolation(), depending on interpolationIsStarted().

Definition at line 272 of file keyFrameInterpolator.h.

void KeyFrameInterpolator::update ( )

privatevirtualslot

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 true.

Definition at line 72 of file keyFrameInterpolator.cpp.

void KeyFrameInterpolator::updateCurrentKeyFrameForTime ( qreal time )

private

Definition at line 504 of file keyFrameInterpolator.cpp.

void KeyFrameInterpolator::updateModifiedFrameValues ( )

private

Definition at line 423 of file keyFrameInterpolator.cpp.

void KeyFrameInterpolator::updateSplineCache ( )

private

Definition at line 555 of file keyFrameInterpolator.cpp.

Member Data Documentation

bool qglviewer::KeyFrameInterpolator::closedPath_

private

Definition at line 344 of file keyFrameInterpolator.h.

QMutableListIterator<KeyFrame*>* qglviewer::KeyFrameInterpolator::currentFrame_[4]

private

Definition at line 330 of file keyFrameInterpolator.h.

bool qglviewer::KeyFrameInterpolator::currentFrameValid_

private

Definition at line 350 of file keyFrameInterpolator.h.

Frame* qglviewer::KeyFrameInterpolator::frame_

private

Definition at line 334 of file keyFrameInterpolator.h.

qreal qglviewer::KeyFrameInterpolator::interpolationSpeed_

private

Definition at line 340 of file keyFrameInterpolator.h.

bool qglviewer::KeyFrameInterpolator::interpolationStarted_

private

Definition at line 341 of file keyFrameInterpolator.h.

qreal qglviewer::KeyFrameInterpolator::interpolationTime_

private

Definition at line 339 of file keyFrameInterpolator.h.

QList<KeyFrame*> qglviewer::KeyFrameInterpolator::keyFrame_

mutableprivate

Definition at line 329 of file keyFrameInterpolator.h.

bool qglviewer::KeyFrameInterpolator::loopInterpolation_

private

Definition at line 345 of file keyFrameInterpolator.h.

QList<Frame> qglviewer::KeyFrameInterpolator::path_

private

Definition at line 331 of file keyFrameInterpolator.h.

bool qglviewer::KeyFrameInterpolator::pathIsValid_

private

Definition at line 348 of file keyFrameInterpolator.h.

int qglviewer::KeyFrameInterpolator::period_

private

Definition at line 338 of file keyFrameInterpolator.h.

bool qglviewer::KeyFrameInterpolator::splineCacheIsValid_

private

Definition at line 351 of file keyFrameInterpolator.h.

QTimer qglviewer::KeyFrameInterpolator::timer_

private

Definition at line 337 of file keyFrameInterpolator.h.

Vec qglviewer::KeyFrameInterpolator::v1

private

Definition at line 352 of file keyFrameInterpolator.h.

Vec qglviewer::KeyFrameInterpolator::v2

private

Definition at line 352 of file keyFrameInterpolator.h.

bool qglviewer::KeyFrameInterpolator::valuesAreValid_

private

Definition at line 349 of file keyFrameInterpolator.h.

The documentation for this class was generated from the following files:

Classes

Signals

Public Member Functions

Private Slots

Private Member Functions

Private Attributes

Path creation

Associated Frame

Path parameters

Interpolation parameters

Interpolation

Path drawing

XML representation

Detailed Description

Interpolation details

Retrieving interpolated values

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation