QNode Class

(Qt3DCore::QNode)

QNode is the base class of all Qt3D node classes used to build a Qt3D scene. More...

Header:	#include <QNode>
qmake:	QT += 3dcore
Since:	Qt 5.5
Inherits:	QObject
Inherited By:	Qt3DAnimation::QAbstractAnimationClip, Qt3DAnimation::QAbstractClipBlendNode, Qt3DAnimation::QChannelMapper, Qt3DCore::QAbstractSkeleton, Qt3DCore::QComponent, Qt3DCore::QEntity, Qt3DCore::QJoint, Qt3DInput::QAbstractActionInput, Qt3DInput::QAbstractAxisInput, Qt3DInput::QAbstractPhysicalDevice, Qt3DInput::QAction, Qt3DInput::QAxis, Qt3DInput::QAxisSetting, Qt3DRender::QAbstractTexture, Qt3DRender::QAbstractTextureImage, Qt3DRender::QAttribute, Qt3DRender::QBuffer, Qt3DRender::QEffect, Qt3DRender::QFilterKey, Qt3DRender::QFrameGraphNode, Qt3DRender::QGeometry, Qt3DRender::QParameter, Qt3DRender::QPickingSettings, Qt3DRender::QRenderPass, Qt3DRender::QRenderState, Qt3DRender::QRenderTargetOutput, Qt3DRender::QShaderImage, Qt3DRender::QShaderProgram, Qt3DRender::QShaderProgramBuilder, Qt3DRender::QTechnique, and Qt3DRender::Quick::QScene2D

This class was introduced in Qt 5.5.

• List of all members, including inherited members

Public Types

enum	PropertyTrackingMode { TrackFinalValues, DontTrackValues, TrackAllValues }

Properties

• defaultPropertyTrackingMode : PropertyTrackingMode
• enabled : bool
• parent : Qt3DCore::QNode*

Public Functions

	QNode(Qt3DCore::QNode *parent = nullptr)
bool	blockNotifications(bool block)
Qt3DCore::QNodeVector	childNodes() const
void	clearPropertyTracking(const QString &propertyName)
void	clearPropertyTrackings()
Qt3DCore::QNode::PropertyTrackingMode	defaultPropertyTrackingMode() const
Qt3DCore::QNodeId	id() const
bool	isEnabled() const
bool	notificationsBlocked() const
Qt3DCore::QNode *	parentNode() const
Qt3DCore::QNode::PropertyTrackingMode	propertyTracking(const QString &propertyName) const
QNodeCommand::CommandId	sendCommand(const QString &name, const QVariant &data = QVariant(), QNodeCommand::CommandId replyTo = QNodeCommand::CommandId())
void	sendReply(const Qt3DCore::QNodeCommandPtr &command)
void	setPropertyTracking(const QString &propertyName, Qt3DCore::QNode::PropertyTrackingMode trackMode)

Public Slots

void	setDefaultPropertyTrackingMode(Qt3DCore::QNode::PropertyTrackingMode mode)
void	setEnabled(bool isEnabled)
void	setParent(Qt3DCore::QNode *parent)

Signals

void	defaultPropertyTrackingModeChanged(Qt3DCore::QNode::PropertyTrackingMode mode)
void	enabledChanged(bool enabled)
void	nodeDestroyed()
void	parentChanged(QObject *parent)

Protected Functions

void	notifyObservers(const Qt3DCore::QSceneChangePtr &change)
virtual void	sceneChangeEvent(const Qt3DCore::QSceneChangePtr &change)

Related Non-Members

typedef	QNodePtr
typedef	QNodeVector
Qt3DCore::QNodeId	qIdForNode(Qt3DCore::QNode *node)
Qt3DCore::QNodeIdVector	qIdsForNodes(const T &nodes)

Detailed Description

The owernship of QNode is determined by the QObject parent/child relationship between nodes. By itself, a QNode has no visual appearance and no particular meaning, it is there as a way of building a node based tree structure.

The parent of a QNode instance can only be another QNode instance.

Each QNode instance has a unique id that allows it to be recognizable from other instances.

When properties are defined on a QNode subclass, their NOTIFY signal will automatically generate notifications that the Qt3D backend aspects will receive.

See also QEntity and QComponent.

Member Type Documentation

enum QNode::PropertyTrackingMode

Indicates how a QNode listens for property updates.

Constant	Value	Description
Qt3DCore::QNode::TrackFinalValues	0	Tracks final values
Qt3DCore::QNode::DontTrackValues	1	Does not track values
Qt3DCore::QNode::TrackAllValues	2	Tracks all values

Member Function Documentation

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

Creates a new QNode instance with parent parent.

Note: The backend aspects will be notified that a QNode instance is part of the scene only if it has a parent; unless this is the root node of the Qt3D scene.

See also setParent().

[signal] void QNode::nodeDestroyed()

Emitted when the node is destroyed.

bool QNode::blockNotifications(bool block)

If block is true, property change notifications sent by this object to aspects are blocked. If block is false, no such blocking will occur.

The return value is the previous value of notificationsBlocked().

Note that the other notification types will be sent even if the notifications for this object have been blocked.

See also notificationsBlocked().

Qt3DCore::QNodeVector QNode::childNodes() const

Returns a list filled with the QNode children of the current QNode instance.

void QNode::clearPropertyTracking(const QString &propertyName)

Clears the tracking property called propertyName.

void QNode::clearPropertyTrackings()

Erases all values that have been saved by the property tracking.

Qt3DCore::QNode::PropertyTrackingMode QNode::defaultPropertyTrackingMode() const

Returns the default property tracking mode which determines whether a QNode should be listening for property updates.

Note: Getter function for property defaultPropertyTrackingMode.

See also setDefaultPropertyTrackingMode().

Qt3DCore::QNodeId QNode::id() const

Returns the id that uniquely identifies the QNode instance.

bool QNode::notificationsBlocked() const

Returns true if aspect notifications are blocked; otherwise returns false. By default, notifications are not blocked.

See also blockNotifications().

[protected] void QNode::notifyObservers(const Qt3DCore::QSceneChangePtr &change)

Sends the change QSceneChangePtr to any QBackendNodes in the registered aspects that correspond to this QNode.

You only need to call this function if you wish to send a specific type of change in place of the automatic handling.

Note: as of Qt 5.14, change messages are deprecated and should not be used, in particular for properties.

Qt3DCore::QNode::PropertyTrackingMode QNode::propertyTracking(const QString &propertyName) const

Returns the tracking mode of propertyName.

See also setPropertyTracking().

[virtual protected] void QNode::sceneChangeEvent(const Qt3DCore::QSceneChangePtr &change)

Called when one or more backend aspects sends a notification change to the current Qt3DCore::QNode instance.

Note: This method should be reimplemented in your subclasses to properly handle the change.

QNodeCommand::CommandId QNode::sendCommand(const QString &name, const QVariant &data = QVariant(), QNodeCommand::CommandId replyTo = QNodeCommand::CommandId())

Sends a command message to the backend node

Creates a QNodeCommand message and dispatches it to the backend node. The command is given and a name and some data which can be used in the backend node to perform various operations. This returns a CommandId which can be used to identify the initial command when receiving a message in reply. If the command message is to be sent in reply to another command, replyTo contains the id of that command.

See also QNodeCommand and QNode::sendReply.

void QNode::sendReply(const Qt3DCore::QNodeCommandPtr &command)

Send a command back to the backend node.

Assumes the command is to be to sent back in reply to itself to the backend node.

See also QNodeCommand and QNode::sendCommand.

void QNode::setPropertyTracking(const QString &propertyName, Qt3DCore::QNode::PropertyTrackingMode trackMode)

Sets the property tracking for propertyName and trackMode.

See also propertyTracking().