Qt 5.9 | Qt Quick | Scene Graph Adaptations

Qt 5.9.9 Reference Documentation

# Scene Graph Adaptations

## Scene Graph Adaptations in Qt Quick

Originally Qt Quick always relied on OpenGL (OpenGL ES 2.0 or OpenGL 2.0) for parsing the scene graph and rendering the results to a render target. From Qt 5.8 onwards Qt Quick also supports rendering in software and with Direct3D 12.

## Switching Between the Adaptation Used by the Application

The default rendering backend is still OpenGL, or - in Qt builds with disabled OpenGL support - the software renderer. This can be overridden either by using an environment variable or a C++ API. The former consists of setting the `QT_QUICK_BACKEND` or the legacy `QMLSCENE_DEVICE` environment variable before launching applications. The latter is done by calling QQuickWindow::setSceneGraphBackend() early in the application's main() function.

The supported backends are the following

- OpenGL - Requested by the string `""` or the enum value QSGRendererInterface::OpenGL.
- Software - Requested by the string `"software"` or the enum value QSGRendererInterface::Software.
- Direct3D 12 - Requested by the string `"d3d12"` or the enum value QSGRendererInterface::Direct3D12.
- OpenVG - Requested by the string `"openvg"` or the enum value QSGRendererInterface::OpenVG.

When in doubt which backend is in use, enable basic scenegraph information logging via the `QSG_INFO` environment variable or the `qt.scenegraph.general` logging category. This will result in printing some information during application startup onto the debug output.

Note: Adaptations other than OpenGL will typically come with a set of limitations since they are unlikely to provide a feature set 100% compatible with OpenGL. However, they may provide their own specific advantages in certain areas. Refer to the sections below for more information on the various adaptations.

## OpenGL ES 2.0 and OpenGL 2.0 Adaptation

The default adaptation capable of providing the full Qt Quick 2 feature set is the OpenGL adaptation. All of the details of the OpenGL adaptation can are available here: OpenGL Adaptation

## Software Adaptation

The Software adaptation is an alternative renderer for Qt Quick 2 that uses the raster paint engine to render the contents of the scene graph. The details for this adaptation are available here: Software Adaptation

## Direct3D 12 (experimental)

The Direct3D 12 adaptation is an alternative renderer for Qt Quick 2 when running on Windows 10, both for Win32 and UWP applications. The details for this adaptation are available here: Direct3D 12 Adaptation

## OpenVG

The OpenVG adaptation is an alternative renderer for Qt Quick 2 that will renderer the contents of the scene graph using OpenVG commands to provide hardware-acclerated 2D vector and raster graphics. The details for this adaptation are available here: OpenVG Adaptation