Question

I have the following code:

paintGL()
{

    if(mouse_was_clicked)
    {
       ... do the color picking with openGL to identify a clicked element

       ... !!! now I need to call again paintGL() to switch the selected element from the 
              old one to the new one but I can't create a recursive cycle!
    }
    else
    {
       ... normal code to draw the scene and the selected element in red ...
    }
}

As the lines suggest, I need a way to call once more the paint event.. is there any way to accomplish this without creating a potential livelock? Something like deferring a new paint event?

Answer 1

If the control flow within your paintGL() is that simple, just make sure that the contens currently being in the else block are executed in every case:

void MyWidget::paintGL()
{
    if(mouse_was_clicked)
    {
        ... do the color picking with openGL to identify a clicked element
    }

    ... normal code to draw the scene and the selected element in red ...
}