QMemoryBarrier Class

(Qt3DRender::QMemoryBarrier)

Class to emplace a memory barrier. More...

Header:	#include <QMemoryBarrier>
qmake:	QT += 3drender
Since:	Qt 5.9
Instantiated By:	MemoryBarrier
Inherits:	Qt3DRender::QFrameGraphNode

• List of all members, including inherited members
• Obsolete members

Public Types

enum	Operation { None, ElementArray, Uniform, TextureFetch, ..., All }
flags	Operations

Public Functions

	QMemoryBarrier(Qt3DCore::QNode *parent = nullptr)
virtual	~QMemoryBarrier()
Qt3DRender::QMemoryBarrier::Operations	waitOperations() const

• 1 public function inherited from Qt3DRender::QFrameGraphNode
• 13 public functions inherited from Qt3DCore::QNode
• 31 public functions inherited from QObject

Public Slots

void	setWaitOperations(QMemoryBarrier::Operations operations)

• 3 public slots inherited from Qt3DCore::QNode
• 1 public slot inherited from QObject

Signals

void	waitOperationsChanged(QMemoryBarrier::Operations barrierTypes)

• 4 signals inherited from Qt3DCore::QNode
• 2 signals inherited from QObject

Static Public Members

const QMetaObject

staticMetaObject

• 9 static public members inherited from QObject

Protected Functions

QMemoryBarrier(Qt3DRender::QMemoryBarrierPrivate &dd, Qt3DCore::QNode *parent = nullptr)

• 1 protected function inherited from Qt3DRender::QFrameGraphNode
• 2 protected functions inherited from Qt3DCore::QNode
• 9 protected functions inherited from QObject

Additional Inherited Members

• 3 properties inherited from Qt3DCore::QNode
• 1 property inherited from QObject

Detailed Description

Class to emplace a memory barrier.

A Qt3DRender::QMemoryBarrier FrameGraph node is used to emplace a specific memory barrier at a specific time of the rendering. This is required to properly synchronize drawing and compute commands on the GPU.

The barrier defines the ordering of memory operations issued by a prior command. This means that if command1 is manipulating a buffer that is to be used as a vertex attribute buffer in a following command2, then the memory barrier should be placed after command1 and setting the appropriate barrier type for vertex attribute buffer.

When a QMemoryBarrier node is found in a FrameGraph branch, the barrier will be enforced prior to any draw or compute command even if these are defined deeper in the branch.

For OpenGL rendering, this page gives more info about the Memory Model

Member Type Documentation

enum QMemoryBarrier::Operationflags QMemoryBarrier::Operations

This enum type describes types of buffer to be cleared.

Constant	Value
Qt3DRender::QMemoryBarrier::None	0
Qt3DRender::QMemoryBarrier::ElementArray	(1 << 1)
Qt3DRender::QMemoryBarrier::Uniform	(1 << 2)
Qt3DRender::QMemoryBarrier::TextureFetch	(1 << 3)
Qt3DRender::QMemoryBarrier::ShaderImageAccess	(1 << 4)
Qt3DRender::QMemoryBarrier::Command	(1 << 5)
Qt3DRender::QMemoryBarrier::PixelBuffer	(1 << 6)
Qt3DRender::QMemoryBarrier::TextureUpdate	(1 << 7)
Qt3DRender::QMemoryBarrier::BufferUpdate	(1 << 8)
Qt3DRender::QMemoryBarrier::FrameBuffer	(1 << 9)
Qt3DRender::QMemoryBarrier::TransformFeedback	(1 << 10)
Qt3DRender::QMemoryBarrier::AtomicCounter	(1 << 11)
Qt3DRender::QMemoryBarrier::ShaderStorage	(1 << 12)
Qt3DRender::QMemoryBarrier::QueryBuffer	(1 << 13)
Qt3DRender::QMemoryBarrier::VertexAttributeArray	(1 << 0)
Qt3DRender::QMemoryBarrier::All	0xFFFFFFFF

The Operations type is a typedef for QFlags<Operation>. It stores an OR combination of Operation values.

Member Function Documentation

QMemoryBarrier::QMemoryBarrier(Qt3DCore::QNode *parent = nullptr)

Default constructs an instance of QMemoryBarrier.

[protected] QMemoryBarrier::QMemoryBarrier(Qt3DRender::QMemoryBarrierPrivate &dd, Qt3DCore::QNode *parent = nullptr)

Default constructs an instance of QMemoryBarrier.

[virtual] QMemoryBarrier::~QMemoryBarrier()

Destroys the instance of QMemoryBarrier. The destructor is virtual.

[slot] void QMemoryBarrier::setWaitOperations(QMemoryBarrier::Operations operations)

See also waitOperations().

Qt3DRender::QMemoryBarrier::Operations QMemoryBarrier::waitOperations() const

See also setWaitOperations().

[signal] void QMemoryBarrier::waitOperationsChanged(QMemoryBarrier::Operations barrierTypes)