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<title>libQGLViewer keyFrames example</title>
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<h1>The keyFrames example</h1>
<center>
<img src="../images/keyFrames.jpg" width="300" height="200" alt="keyFrames"/>
</center>
<p>
The <code>KeyFrameInterpolator</code> test example.
</p>
<p>
KeyFrameInterpolator smoothly interpolate their attached Frame over time on a path defined by
Frames. The interpolation can be started/stopped/reset, played in loop, played at a different
speed, etc...
</p>
<p>
In this examples, the path is defined by four ManipulatedFrame which all can be moved with the
mouse. The interpolating path is updated accordingly.
</p>
<p>
The path and the interpolating axis are drawn using KeyFrameInterpolator::drawPath().
</p>
<p>
By default, the Camera holds 12 KeyFrameInterpolator, binded to the F1-12 keys. Use Alt-Fx to
define a new keyFrame for path x, and simply press Fx to play/pause the path x. See the <a
href="../shortcuts.html">shortcuts</a> page for details.
</p>
<h2>keyFrames.h</h2>
<pre>
<span class="dir">#include <QGLViewer/qglviewer.h>
</span>
<span class="key">class </span>Viewer : <span class="key">public </span>QGLViewer
{
<span class="key">public </span>:
Viewer();
<span class="key">protected </span>:
<span class="key">virtual </span><span class="typ">void </span>draw();
<span class="key">virtual </span><span class="typ">void </span>keyPressEvent(QKeyEvent *e);
<span class="key">virtual </span>QString helpString() <span class="typ">const</span>;
<span class="key">private </span>:
qglviewer::ManipulatedFrame** keyFrame_;
qglviewer::KeyFrameInterpolator kfi_;
<span class="typ">const int </span>nbKeyFrames;
<span class="typ">int </span>currentKF_;
};</pre>
<h2>keyFrames.cpp</h2>
<pre>
<span class="dir">#include </span><span class="dstr">"keyFrames.h"</span><span class="dir">
</span>
<span class="key">using namespace </span>qglviewer;
<span class="key">using namespace </span>std;
Viewer::Viewer()
: nbKeyFrames(<span class="num">4</span>)
{
restoreFromFile();
<span class="com">// myFrame is the Frame that will be interpolated.
</span> Frame* myFrame = <span class="key">new </span>Frame();
<span class="com">// Set myFrame as the KeyFrameInterpolator interpolated Frame.
</span> kfi_.setFrame(myFrame);
kfi_.setLoopInterpolation();
<span class="com">// An array of manipulated (key) frames.
</span> keyFrame_ = <span class="key">new </span>ManipulatedFrame*[nbKeyFrames];
<span class="com">// Create an initial path
</span> <span class="key">for </span>(<span class="typ">int </span>i=<span class="num">0</span>; i<nbKeyFrames; i++)
{
keyFrame_[i] = <span class="key">new </span>ManipulatedFrame();
keyFrame_[i]->setPosition(<span class="num">-1.0 </span>+ <span class="num">2.0</span>*i/(nbKeyFrames-1), <span class="num">0.0</span>, <span class="num">0.0</span>);
kfi_.addKeyFrame(keyFrame_[i]);
}
connect(&kfi_, SIGNAL(interpolated()), SLOT(updateGL()));
kfi_.startInterpolation();
currentKF_ = <span class="num">0</span>;
setManipulatedFrame(keyFrame_[currentKF_]);
<span class="com">// Save CAMERA binding. See setMouseStateKey() documentation.
</span> setMouseStateKey(QGLViewer::CAMERA, Qt::AltButton);
setMouseStateKey(QGLViewer::FRAME, Qt::NoButton);
setMouseStateKey(QGLViewer::CAMERA, Qt::ControlButton);
<span class="com">// Enable direct frame manipulation when the mouse hovers.
</span> setMouseTracking(<span class="key">true</span>);
help();
}
QString Viewer::helpString() <span class="typ">const
</span>{
QString text(<span class="str">"<h2>K e y F r a m e s</h2>"</span>);
text += <span class="str">"A frame is animated using a <i>KeyFrameInterpolator</i>.<br>"</span>;
text += <span class="str">"Use the left and right arrows to change the manipulated frame.<br>"</span>;
text += <span class="str">"<b>+/-</b> changes the interpolation speed.<br>"</span>;
text += <span class="str">"<b>Return</b> starts-stops the interpolation.<br>"</span>;
text += <span class="str">"Press <b>Control</b> to move the camera."</span>;
<span class="key">return </span>text;
}
<span class="typ">void </span>Viewer::keyPressEvent(QKeyEvent *e)
{
<span class="key">switch </span>(e->key())
{
<span class="key">case </span>Qt::Key_Left :
currentKF_ = (currentKF_+nbKeyFrames-1) % nbKeyFrames;
setManipulatedFrame(keyFrame_[currentKF_]);
updateGL();
<span class="key">break</span>;
<span class="key">case </span>Qt::Key_Right :
currentKF_ = (currentKF_+<span class="num">1</span>) % nbKeyFrames;
setManipulatedFrame(keyFrame_[currentKF_]);
updateGL();
<span class="key">break</span>;
<span class="key">case </span>Qt::Key_Return :
<span class="key">if </span>(e->state() != shortcutStateKey(FULL_SCREEN))
kfi_.toggleInterpolation();
<span class="key">else
</span>QGLViewer::keyPressEvent(e);
<span class="key">break</span>;
<span class="key">case </span>Qt::Key_Plus :
kfi_.setInterpolationSpeed(kfi_.interpolationSpeed()+<span class="num">0.25</span>);
<span class="key">break</span>;
<span class="key">case </span>Qt::Key_Minus :
kfi_.setInterpolationSpeed(kfi_.interpolationSpeed()<span class="num">-0.25</span>);
<span class="key">break</span>;
<span class="com">// case Qt::Key_C :
</span> <span class="com">// kfi_.setClosedPath(!kfi_.closedPath());
</span> <span class="com">// break;
</span> <span class="key">default</span>:
QGLViewer::keyPressEvent(e);
}
}
<span class="typ">void </span>Viewer::draw()
{
glPushMatrix();
glMultMatrixd(kfi_.frame()->matrix());
drawAxis(<span class="num">0.3</span>);
glPopMatrix();
kfi_.drawPath(<span class="num">5</span>, <span class="num">30</span>);
<span class="key">for </span>(<span class="typ">int </span>i=<span class="num">0</span>; i<nbKeyFrames; ++i)
{
glPushMatrix();
glMultMatrixd(kfi_.keyFrame(i).matrix());
<span class="key">if </span>((i == currentKF_) || (keyFrame_[i]->grabsMouse()))
drawAxis(<span class="num">0.4</span>);
<span class="key">else
</span>drawAxis(<span class="num">0.2</span>);
glPopMatrix();
}
}</pre>
<h2>main.cpp</h2>
<pre>
<span class="dir">#include </span><span class="dstr">"keyFrames.h"</span><span class="dir">
</span><span class="dir">#include <qapplication.h>
</span>
<span class="typ">int </span>main(<span class="typ">int </span>argc, <span class="typ">char</span>** argv)
{
<span class="com">// Read command lines arguments.
</span> QApplication application(argc,argv);
<span class="com">// Instantiate the viewer, show it on screen.
</span> Viewer viewer;
viewer.show();
<span class="com">// Set the viewer as the application main widget.
</span> application.setMainWidget(&viewer);
<span class="com">// Run main loop.
</span> <span class="key">return </span>application.exec();
}</pre>
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<i>Last modified on Thursday, February 5, 2004.</i>
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