Anyone using Ogre with Qt 4.5? [SOLVED]

[PolyVox]

Hi guys,

Has anyone here sucessfully embedded an Ogre window into an application built with Qt 4.5? I'd heard my QtOgre framework had problems with it, and today I upgraded and saw the problem for myself. The image only appears in 'bands' which move up and down very quickly. Hence you do see the whole image, but there is a lot of flickering.

It occurs with all Qt graphics systems ('native', 'raster', and 'opengl') and with both Ogre's OpenGL and Direct3D rendersystems.

Actually the flickering does go away if I pass Ogre a 'parentWindowHandle' rather than an 'externalWindowHandle', but then the image is offset by a few hundred pixels. Does anyone know the conceptual difference between these flags?

I don't really know how to fix it, so I'll be reverting to Qt 4.4 unless anyone has any ideas...

[rtlpixy]

I have just fixed it now !

You have simply to override the paintEngine method on the OgreWidget and return 0.

Code: Select all

  
  
  QPaintEngine *OgreWidget:: paintEngine() const
  {
    return 0;
  }

On Windows works, if you can test on other platforms it is better.

Best,

Angelo

[nikki]

Or you could just tell the users it's a 'feature' and forget about it.

[PolyVox]

I have just fixed it now !

You have simply to override the paintEngine method on the OgreWidget and return 0.

Excellent work! I just tested it and it seems good. You just saved me a lot of pain - thanks a lot! I will add this fix to SVN.

[Mans]

Hi,

Has anyone managed to make it work on a Mac ?? I had an application that worked with Qt 4.4.0 and I added the exact same fix to make it work with 4.5 (override paintEngine to make it return 0), but I have a blank widget on Mac... It works fine on Linux&Windows though.
I am using Qt 4.5.2 and Ogre 1.4.9. Any help will be more than welcome...

[jacmoe]

qtOgitor runs on the Mac.
I am not sure if it does using Ogre 1.4.9, but it does using Ogre trunk and Qt 4.5.

[Mans]

Ok, thanks ! I am going to try to compare our sources then. I'll post something here if I manage to make it work !

[Mans]

Unfortunately QtOgitor is using Ogre >= 1.7. And I tried to compare our code, the widget initialization and painting are identical... Maybe I will try to upgrade my Ogre version, but I am quite afraid of the time I will spend on making it compile .

[jacmoe]

I told you we were using trunk.

I think it's definitely worth your while to upgrade.
Especially since Masterfalcon joined the team we should see much improved support for the Mac.

[Mans]

Oups, sorry I read your post too quickly .

I just passed Ogre from 1.4.3 to 1.6.3 (latest SDK released), but I still got the same problem : my widget that should display Ogre is all blank !!

I wasn't doing all the hiddenparam stuff at OgreWidget initialization (and the creation of another OgreRenderWindow), but even by doing so it does not work... I am quite stuck here, especially because I am a windows developper and don't know very well MacOSX

[joew]

Try doing what Jacmoe said and grab the source from trunk, I am using it with Qt 4.5 on the mac and have no problems.

[Mans]

Yes I don't see any other option at the moment. I am going to try to compare a little more thoroughly the way we wrote our OgreWidget class before that though.
I don't see why it will work with a more recent version of Ogre though, as it is a change in Qt that causes the regression... But I will test it anyway

[Mans]

Unfortunately, I didn't manage to compile Ogre from the trunk... It seems like I am going to spend hours on it...

Is there anyone that could explain to me the code of Qt Ogitor ? Because I don't understand why you need to create a "hiddenparams" stuff, and initialize a second Ogre::RenderWindow with it. I tried to do that as well, but it does not change anything...

[jacmoe]

'hiddenParams' is used for the primary, hidden window. It passes the handle of the grand-parent window.
Do not worry about that.

Code: Select all

    Ogre::NameValuePairList params;
    params["externalWindowHandle"] = Ogre::StringConverter::toString((size_t) (this->winId()));
    mWhateverRenderWindow = mWhateverOgreRoot->createRenderWindow( "WhateverRenderWindow",
                                                   this->width(),
                                                   this->height(),
                                                   false,
                                                   &params );

Provided you've got the latest Ogre, that code should work.

[Mans]

Hi,

Thanks for your answer !

Is it a known problem that the latest Ogre is needed with Qt 4.5 ? My problem is the following : we are about to release a new version of a professional tool. And I don't really feel comfortable releasing something with Ogre trunk. I'd rather use an official SDK from a stable branch (1.4.x or 1.6.x)...

Sorry to be so painful...

[jacmoe]

The only thing I can think of is .. try and use parentWindowHandle instead.

[Mans]

Hi,

Thanks for the suggestion ! I just tried to do so and something odd happens : my ogreWidget is still all blank. However, I have another floating QWidget (named after my renderwidget "View"). And this widget is correctly resized when I resize my ogrewidget. Quite strange actually. But I do see some Ogre rendering, which seems good !
The only other way I found to see something from Ogre was to set the "fullscreen" param to true when creating the renderwindow. What I see then is crazy, but I can distinguish some part from Ogre...

Well I don't really know what to do next, besides crying under my desk

[Mans]

Hi,

I just solved my problem after crying for some months. I post the solution here, as it may save some lives of a future generation ^^.

My problem was that I initialized all the Ogre stuff too soon (before any QWidget was displayed), and it seems that the window handle returned by Qt was not valid yet. I now call the Ogre initialization when my mainwindow is about to be displayed for the first time, and it works... Thanks for all the help above !