keyframe_interpolation.cpp

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/*****************************************************************************
** Includes
*****************************************************************************/

#include <qapplication.h>
#include <QGLViewer/qglviewer.h>
#include <QKeyEvent>

using namespace qglviewer;

/*****************************************************************************
 ** KeyframeInterpolation
 *****************************************************************************/

class KeyframeInterpolation : public QGLViewer
{
public :
  KeyframeInterpolation();

protected :
  virtual void draw();
  virtual void keyPressEvent(QKeyEvent *e);
  virtual QString helpString() const;

private :
  qglviewer::ManipulatedFrame** keyFrame_;
  qglviewer::KeyFrameInterpolator kfi_;
  const int nbKeyFrames;
  int currentKF_;
};

/*****************************************************************************
 ** KeyframeInterpolation
 *****************************************************************************/

KeyframeInterpolation::KeyframeInterpolation()
  : nbKeyFrames(4)
{
  restoreStateFromFile();

  // myFrame is the Frame that will be interpolated.
  Frame* myFrame = new Frame();

  // Set myFrame as the KeyFrameInterpolator interpolated Frame.
  kfi_.setFrame(myFrame);
  kfi_.setLoopInterpolation();

  // An array of manipulated (key) frames.
  keyFrame_ = new ManipulatedFrame*[nbKeyFrames];

  // Create an initial path
  for (int i=0; i<nbKeyFrames; i++)
        {
          keyFrame_[i] = new ManipulatedFrame();
          keyFrame_[i]->setPosition(-1.0 + 2.0*i/(nbKeyFrames-1), 0.0, 0.0);
          kfi_.addKeyFrame(keyFrame_[i]);
        }

  currentKF_ = 0;
  setManipulatedFrame(keyFrame_[currentKF_]);

  // Enable direct frame manipulation when the mouse hovers.
  setMouseTracking(true);

  setKeyDescription(Qt::Key_Plus, "Increases interpolation speed");
  setKeyDescription(Qt::Key_Minus, "Decreases interpolation speed");
  setKeyDescription(Qt::Key_Left, "Selects previous key frame");
  setKeyDescription(Qt::Key_Right, "Selects next key frame");
  setKeyDescription(Qt::Key_Return, "Starts/stops interpolation");

  help();

  connect(&kfi_, SIGNAL(interpolated()), SLOT(updateGL()));
  kfi_.startInterpolation();
}

QString KeyframeInterpolation::helpString() const
{
  QString text("<h2>K e y F r a m e s</h2>");
  text += "A <i>KeyFrameInterpolator</i> holds an interpolated path defined by key frames. ";
  text += "It can then smoothly make its associed frame follow that path. Key frames can interactively be manipulated, even ";
  text += "during interpolation.<br><br>";
  text += "Note that the camera holds 12 such keyFrameInterpolators, binded to F1-F12. Press <b>Alt+Fx</b> to define new key ";
  text += "frames, and then press <b>Fx</b> to make the camera follow the path. Press <b>C</b> to visualize these paths.<br><br>";
  text += "<b>+/-</b> changes the interpolation speed. Negative values are allowed.<br><br>";
  text += "<b>Return</b> starts-stops the interpolation.<br><br>";
  text += "Use the left and right arrows to change the manipulated KeyFrame. ";
  text += "Press <b>Control</b> to move it or simply hover over it.";
  return text;
}

void KeyframeInterpolation::keyPressEvent(QKeyEvent *e)
{
  switch (e->key())
        {
        case Qt::Key_Left :
          currentKF_ = (currentKF_+nbKeyFrames-1) % nbKeyFrames;
          setManipulatedFrame(keyFrame_[currentKF_]);
          updateGL();
          break;
        case Qt::Key_Right :
          currentKF_ = (currentKF_+1) % nbKeyFrames;
          setManipulatedFrame(keyFrame_[currentKF_]);
          updateGL();
          break;
        case Qt::Key_Return :
          kfi_.toggleInterpolation();
          break;
        case Qt::Key_Plus :
          kfi_.setInterpolationSpeed(kfi_.interpolationSpeed()+0.25);
          break;
        case Qt::Key_Minus :
          kfi_.setInterpolationSpeed(kfi_.interpolationSpeed()-0.25);
          break;
        // case Qt::Key_C :
          // kfi_.setClosedPath(!kfi_.closedPath());
          // break;
        default:
          QGLViewer::keyPressEvent(e);
        }
}

void KeyframeInterpolation::draw()
{
  // Draw interpolated frame
  glPushMatrix();
  glMultMatrixd(kfi_.frame()->matrix());
  drawAxis(0.3f);
  glPopMatrix();

  kfi_.drawPath(5, 10);

  for (int i=0; i<nbKeyFrames; ++i)
        {
          glPushMatrix();
          glMultMatrixd(kfi_.keyFrame(i).matrix());

          if ((i == currentKF_) || (keyFrame_[i]->grabsMouse()))
        drawAxis(0.4f);
          else
        drawAxis(0.2f);

          glPopMatrix();
        }
}

/*****************************************************************************
** Main
*****************************************************************************/

int main(int argc, char** argv)
{
  QApplication application(argc,argv);

  KeyframeInterpolation viewer;

  viewer.setWindowTitle("keyFrames");

  viewer.show();

  return application.exec();
}