Qt rendering using OpenGL

Question

I'm working on a QML application for an embedded platform which includes a GridView widget containing images. It's important for me that scrolling through the GridView will be smooth and will not put load on the CPU. Can I expect Qt to use OpenGL to render the GridView?

As far as I know about Qt QML you can use shaders (there are examples on the Qt site) ... I guess some OpenGl rendering is involved. — Thomas Vincent, Jun 27 '11 at 13:46
Shaders will come with QtQuick 2.0 (Qt 5.0) or you have to use QtQuick3D. — blakharaz, Jun 27 '11 at 18:36

score 5 · Accepted Answer · answered Jun 29 '11 at 10:01

5

I faced with the same problem.

QApplication::setGraphicsSystem(QLatin1String("opengl"));

haven`t work for me. So i set the OGWidget as a viewport:

QDeclarativeView mainwindow;
mainwindow.setSource(QUrl::fromLocalFile("./qml/app.qml"));
QGLFormat format = QGLFormat(QGL::DirectRendering); // you can play with other rendering formats like DoubleBuffer or SimpleBuffer
format.setSampleBuffers(false);
QGLWidget *glWidget = new QGLWidget(format);
glWidget->setAutoFillBackground(false);
mainwindow.setViewport(glWidget);

and do not forget to add opengl in *.pro file.

answered Jun 29 '11 at 10:01

avida

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which qt version did you use? – sayyed mohsen zahraee May 13 '15 at 06:15
It was latest version at the moment. AFAIR, 4.6 with qtquick 1.0 – avida May 14 '15 at 10:55

score 3 · Answer 2 · answered Jun 27 '11 at 18:33

3

Depending on your platform use

QApplication::setGraphicsSystem(QLatin1String("opengl"));

or (Symbian)

QApplication::setGraphicsSystem(QLatin1String("openvg"));

before you instantiate the QApplication object.

answered Jun 27 '11 at 18:33

blakharaz

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score 2 · Answer 3 · answered Jun 27 '11 at 17:37

2

By default Qt does not use the OpenGL render backend. You can enforce it by using a QGlWidget. In your case, as you want to use a stock widget, you can set the render backend as a command line option:

<binary name> -graphicssystem opengl

answered Jun 27 '11 at 17:37

ypnos

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["-graphicssystem" option was deleted from Qt5](https://bugreports.qt.io/browse/QTBUG-41265) – Color Oct 11 '17 at 00:11

Qt rendering using OpenGL

3 Answers3

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