Mulitple openGL windows

[tcsvw5]

Hello,

I'm writing an app where I need multiple openGL windows running. This windows are created dynamically by the user. The problem is as soon as the second window opens the first stops processing mouse events and never repaints. The second window works fine but the first stops. I'm hoping this is just something stupid i've done wrong and there is an easy fix.
Any ideas?
Travis

[jacek]

Could you post the code that opens that new window?

[tcsvw5]

CGraphContainer* tmp = new CGraphContainer(); tmp->GetGraph()->SetPowerSystem(m_graph->GetPowerSystem());
tmp->GetGraph()->ConnectToServer("dell1.cs.umr.edu", 1208);
tmp->GetGraph()->SetHistory(m_graph->GetHistory());
tmp->show();
m_graphList.append(tmp);

CGraphContainer extends QMainWindow and is pretty basic just creates a new CGraph object which extends QGLWidget.

[tcsvw5]

Well, it works fine when I have two separate instances of the application running, just not when I have two windows within the same app.

Travis

[jacek]

CGraphContainer* tmp = new CGraphContainer(); tmp->GetGraph()->SetPowerSystem(m_graph->GetPowerSystem());
tmp->GetGraph()->ConnectToServer("dell1.cs.umr.edu", 1208);
tmp->GetGraph()->SetHistory(m_graph->GetHistory());
tmp->show();
m_graphList.append(tmp);

There's nothing suspicious here. Maybe you block the event loop somewhere? Do you return from the method that shows that new window?

Which Qt version do you use?

[KShots]

I doubt there's anything wrong with your constructor. I ran into something similar with my MDI OGL app. Look at your input processor. Make sure you call updateGL() at the end - it will make that window's OpenGL context the current device context, then update that window. Remember, it will only update when you tell it to update. You either go with event-based updates (preferred) or timer-based updates. Your other window will use the same function (I'm assuming) and work accordingly.

Also, if you don't need to update the display, but you do need data from it, use the makeCurrent() function to make your QGLWidget's device context the current context.

[tcsvw5]

I am using Qt 3.2.1 and both windows have a timer based update scheme every 100ms if needed. The odd thing is that sometimes for a short period of time both windows operate together correctly but eventually the first window stops working.

Travis

[jacek]

How do you trigger the updates? Do you use QTimer?

[KShots]

Then what you need to check is your timer function. Make sure it calls your QGLWidget's updateGL() function on every timer interrupt. I'm 99.9% sure this is what you're running into based on those symptoms.

[tcsvw5]

Yes, I'm using a QTimer to handle this, and it does call updateGL appropriately.
When i break into paintGL both objects get rerendered, however the first qglwidget remains black. This seems to always happen after I resize the first window. Up until then it works fine (handles mouse events; drags the display), but one I resize that first window it goes blank. The second window however works great, no problems.

[jacek]

This seems to always happen after I resize the first window.

What do you do when that widget is resized? Did you reimplement the resizeEvent()?

[nikikko]

Do you call makeCurrent ?
I have the same problem one day, and the solution is to call makeCurrent in the QGLWidget before updateGL.

[yogeshm02]

As far as i understand only one 3d accelerated window can be active at a time.

[jacek]

As far as i understand only one 3d accelerated window can be active at a time.

This shouldn't be a problem. See opengl/textures example.