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/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:FDL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see http://www.qt.io/terms-conditions. For further
** information use the contact form at http://www.qt.io/contact-us.
**
** GNU Free Documentation License Usage
** Alternatively, this file may be used under the terms of the GNU Free
** Documentation License version 1.3 as published by the Free Software
** Foundation and appearing in the file included in the packaging of
** this file. Please review the following information to ensure
** the GNU Free Documentation License version 1.3 requirements
** will be met: http://www.gnu.org/copyleft/fdl.html.
** $QT_END_LICENSE$
**
****************************************************************************/
/*!
\title Scene Graph Adaptations
\page qtquick-visualcanvas-adaptations.html
\section1 Scene Graph Adaptations in Qt Quick
Originally Qt Quick only had one available renderer for parsing the scene graph
and rendering the results to a render target. This renderer is now the default
OpenGL Renderer which supports rendering either using the OpenGL ES 2.0 or
OpenGL 2.0 (with framebuffer object extensions) APIs. The Qt Quick APIs have
originally been designed with the assumption that OpenGL is always available.
However, it is now possible to use other graphics API's to render Qt Quick
scenes using the scene graph APIs.
\section1 Switching between the adaptation used by the application
The default of the OpenGL, or - in Qt builds with disabled OpenGL support - the
software adaptation, can be overridden either by using an environment variable
or a C++ API. The former consists of setting the \c{QT_QUICK_BACKEND} or the
legacy \c{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
\list
\li OpenGL - Requested by the string \c{""} or the enum value QSGRendererInterface::OpenGL.
\li Software - Requested by the string \c{"software"} or the enum value QSGRendererInterface::Software.
\li Direct3D 12 - Requested by the string \c{"d3d12"} or the enum value QSGRendererInterface::Direct3D12.
\endlist
When in doubt which backend is in use, enable basic scenegraph information
logging via the \c{QSG_INFO} environment variable or the
\c{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.
\section1 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
adpatation can are available here
\l{qtquick-visualcanvas-scenegraph-renderer.html}{OpenGL Adaptation}
\section1 Software Adaptation
The Software adaptation is an alternative renderer for \l {Qt Quick} 2 that uses the Raster
paint engine to render the contents of the scene graph instead of OpenGL.
As a result of not using OpenGL to render the scene graph, some features
and optimizations are no longer available. Most Qt Quick 2 applications
will run without modification though any attempts to use unsupported
features will be ignored. By using the Software adpatation it is possible to run Qt
Quick 2 applications on hardware and platforms that do not have OpenGL
support.
The Software adaptation was previously known as the Qt Quick 2D Renderer.
\section2 Shader Effects
ShaderEffect components in QtQuick 2 can not be rendered by the Software adptation.
\section2 Qt Graphical Effects Module
\l {Qt Graphical Effects} uses ShaderEffect items to render effects. If you use
graphical effects from this module, then you should not hide the source
item so that the original item can still be rendered.
\section2 Particle Effects
It is not possible to render particle effects with the Software adaptation. Whenever
possible, remove particles completely from the scene. Otherwise they will still
require some processing, even though they are not visible.
\section2 Sprites
The Sprite item depends on OpenGL functions and will not be visible.
\section2 Rendering Text
The text rendering with the Software adaptation is based on software
rasterization and does not respond as well to transformations such as scaling
as when using OpenGL. The quality is similar to choosing \l [QML] {Text::renderType}
{Text.NativeRendering} with \l [QML] {Text} items.
\section1 Direct3D 12 (experimental)
*/
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