Viadeo Twitter Google Bookmarks ! Facebook Digg del.icio.us MySpace Yahoo MyWeb Blinklist Netvouz Reddit Simpy StumbleUpon Bookmarks Windows Live Favorites 
Logo Documentation Qt ·  Page d'accueil  ·  Tous les espaces de nom  ·  Toutes les classes  ·  Classes principales  ·  Annotées  ·  Classes groupées  ·  Modules  ·  Fonctions  · 

QtOpenGL Module

The QtOpenGL module offers classes that make it easy to use OpenGL in Qt applications. More...

Namespaces

QGLMiscellaneous identifiers used in the Qt OpenGL module

Classes

QGLColormapUsed for installing custom colormaps into QGLWidgets
QGLContextEncapsulates an OpenGL rendering context
QGLFormatThe display format of an OpenGL rendering context
QGLFramebufferObjectEncapsulates an OpenGL framebuffer object
QGLPixelBufferEncapsulates an OpenGL pbuffer
QGLWidgetWidget for rendering OpenGL graphics
QWSGLWindowSurfaceThe drawing area for top-level windows in Qtopia Core on EGL/OpenGLES. It also provides the drawing area for QGLWidgets whether they are top-level windows or child widget of another QWidget

Detailed Description

OpenGL is a standard API for rendering 3D graphics. OpenGL only deals with 3D rendering and provides little or no support for GUI programming issues. The user interface for an OpenGL application must be created with another toolkit, such as Motif on the X platform, Microsoft Foundation Classes (MFC) under Windows, or Qt on both platforms.

Note: OpenGL is a trademark of Silicon Graphics, Inc. in the United States and other countries.

The Qt OpenGL module makes it easy to use OpenGL in Qt applications. It provides an OpenGL widget class that can be used just like any other Qt widget, except that it opens an OpenGL display buffer where you can use the OpenGL API to render the contents.

To include the definitions of the module's classes, use the following directive:

 #include <QtOpenGL>

To link against the module, add this line to your qmake .pro file:

 QT += opengl

The Qt OpenGL module is implemented as a platform-independent Qt/C++ wrapper around the platform-dependent GLX, WGL, or AGL C APIs. The functionality provided is very similar to Mark Kilgard's GLUT library, but with much more non-OpenGL-specific GUI functionality, i.e. the whole Qt API.

Warning: The QtOpenGL module is part of the Qt Desktop Edition and the Qt Open Source Edition. It is available on Windows, X11, and Mac OS X. Qtopia Core supports OpenGL ES (OpenGL for Embedded Systems). To be able to use the OpenGL API in Qtopia Core, it must be integrated with the Q Window System (QWS). See the Qtopia Core and OpenGL documentation for details.

Installation

When you install Qt for X11, the configure script will autodetect if OpenGL headers and libraries are installed on your system, and if so, it will include the QtOpenGL module in the Qt library. (If your OpenGL headers or libraries are placed in a non-standard directory, you may need to change the QMAKE_INCDIR_OPENGL and/or QMAKE_LIBDIR_OPENGL in the config file for your system).

When you install Qt for Windows and Mac OS X, the QtOpenGL module is always included. X11 users might like to read the notes on overlays below.

The QGL documentation assumes that you are familiar with OpenGL programming. If you're new to the subject a good starting point is http://www.opengl.org/.

How to Use X11 Overlays with Qt

X11 overlays are a powerful mechanism for drawing annotations etc., on top of an image without destroying it, thus saving a great deal of image rendering time. For more information, see the highly recommended book OpenGL Programming for the X Window System (Mark Kilgard, Addison Wesley Developers Press 1996).

Warning: The Qt OpenGL Extension includes direct support for the use of OpenGL overlays. For many uses of overlays, this makes the technique described below redundant. The following is a discussion on how to use non-QGL widgets in overlay planes.

In the typical case, X11 overlays can easily be used together with the current version of Qt and the Qt OpenGL Extension. The following requirements apply:

  1. Your X server and graphics card/hardware must support overlays. For many X servers, overlay support can be turned on with a configuration option; consult your X server installation documentation.
  2. Your X server must (be configured to) use an overlay visual as the default visual. Most modern X servers do this, since this has the added advantage that pop-up menus, overlapping windows etc., will not affect underlying images in the main plane, thereby avoiding expensive redraws.
  3. The best (deepest) visual for OpenGL rendering is in the main plane. This is the normal case. Typically, X servers that support overlays provide a 24-bit TrueColor visual in the main plane, and an 8-bit PseudoColor (default) visual in the overlay plane.

Assuming that the requirements mentioned above are met, a QGLWidget will default to using the main plane visual, while all other widgets will use the overlay visual. Thus, we can place a normal widget on top of the QGLWidget, and do drawing on it, without affecting the image in the OpenGL window. In other words, we can use all the drawing capabilities of QPainter to draw annotations, rubberbands, etc. For the typical use of overlays, this is much easier than using OpenGL for rendering annotations.

An overlay plane has a specific color called the transparent color. Pixels drawn in this color will not be visible; instead the underlying OpenGL image will show through.

To use this technique, you must not use the QApplication::ManyColor or QApplication::TrueColor color specification for QApplication, because this will force the normal Qt widgets to use a TrueColor visual, which will typically be in the main plane, not in the overlay plane as desired.

[Previous: QtNetwork Module] [Qt's Modules] [Next: QtSql Module]

Publicité

Best Of

Actualités les plus lues

Semaine
Mois
Année
  1. « Quelque chose ne va vraiment pas avec les développeurs "modernes" », un développeur à "l'ancienne" critique la multiplication des bibliothèques 94
  2. Apercevoir la troisième dimension ou l'utilisation multithreadée d'OpenGL dans Qt, un article des Qt Quarterly traduit par Guillaume Belz 0
  3. Les développeurs ignorent-ils trop les failles découvertes dans leur code ? Prenez-vous en compte les remarques des autres ? 17
  4. Pourquoi les programmeurs sont-ils moins payés que les gestionnaires de programmes ? Manquent-ils de pouvoir de négociation ? 42
  5. Quelles nouveautés de C++11 Visual C++ doit-il rapidement intégrer ? Donnez-nous votre avis 10
  6. Adieu qmake, bienvenue qbs : Qt Building Suite, un outil déclaratif et extensible pour la compilation de projets Qt 17
  7. 2017 : un quinquennat pour une nouvelle version du C++ ? Possible, selon Herb Sutter 9
Page suivante

Le Qt Labs au hasard

Logo

Velours et QML Scene Graph

Les Qt Labs sont les laboratoires des développeurs de Qt, où ils peuvent partager des impressions sur le framework, son utilisation, ce que pourrait être son futur. Lire l'article.

Communauté

Ressources

Liens utiles

Contact

  • Vous souhaitez rejoindre la rédaction ou proposer un tutoriel, une traduction, une question... ? Postez dans le forum Contribuez ou contactez-nous par MP ou par email (voir en bas de page).

Qt dans le magazine

Cette page est une traduction d'une page de la documentation de Qt, écrite par Nokia Corporation and/or its subsidiary(-ies). Les éventuels problèmes résultant d'une mauvaise traduction ne sont pas imputables à Nokia. Qt 4.3
Copyright © 2012 Developpez LLC. Tous droits réservés Developpez LLC. Aucune reproduction, même partielle, ne peut être faite de ce site et de l'ensemble de son contenu : textes, documents et images sans l'autorisation expresse de Developpez LLC. Sinon, vous encourez selon la loi jusqu'à 3 ans de prison et jusqu'à 300 000 E de dommages et intérêts. Cette page est déposée à la SACD.
Vous avez déniché une erreur ? Un bug ? Une redirection cassée ? Ou tout autre problème, quel qu'il soit ? Ou bien vous désirez participer à ce projet de traduction ? N'hésitez pas à nous contacter ou par MP !
 
 
 
 
Partenaires

Hébergement Web