Question

I’m using libqglviewer for a project, I read input from a motion capture device through USB and display this as a human in the viewer. I draw the opengl things in the draw() method of the viewer, it works fine. However, when the motion controllers change, I actually get new position values and i draw these in the viewer, BUT i dont see this update until i click on the viewer screen. Is it possible to update the frames in the viewer by itself?

Answer 1

It looks like you just need to post an updateGL right after you get the new position values.

QGLWidget::updateGL()

    void QGLWidget::updateGL () [virtual slot]
    Updates the widget by calling glDraw().

For painting in 2D the function is called update.

Also, don’t call it from inside your draw method (see updateGL in the libQGLViewer documentation).

This note comes from QWidget::paintEvent():

Note: Generally, you should refrain from calling update() or repaint() inside a paintEvent(). For example, calling update() or repaint() on children inside a paintevent() results in undefined behavior; the child may or may not get a paint event.

The same probably applies for QGLViewer.

You can also use repaint, but is isn’t recommended (see QWidget::repaint()).