QNode Class


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

Public Types

enum PropertyTrackingMode { TrackFinalValues, DontTrackValues, TrackAllValues }


  • 1 property inherited from QObject

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)
  • 34 public functions inherited from QObject

Public Slots

void setDefaultPropertyTrackingMode(Qt3DCore::QNode::PropertyTrackingMode mode)
void setEnabled(bool isEnabled)
void setParent(Qt3DCore::QNode *parent)
  • 1 public slot inherited from QObject


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)
  • 9 protected functions inherited from QObject
typedef QNodePtr
typedef QNodeVector
Qt3DCore::QNodeId qIdForNode(Qt3DCore::QNode *node)
Qt3DCore::QNodeIdVector qIdsForNodes(const T &nodes)

Additional Inherited Members

  • 1 public variable inherited from QObject
  • 10 static public members inherited from QObject
  • 2 protected variables inherited from QObject

Detailed Description

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

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

Property Documentation

defaultPropertyTrackingMode : PropertyTrackingMode

Holds the default property tracking mode which determines whether a QNode should be listening for property updates. This only applies to properties which haven't been overridden by a call to setPropertyTracking.

By default it is set to QNode::TrackFinalValues

Access functions:

Qt3DCore::QNode::PropertyTrackingMode defaultPropertyTrackingMode() const
void setDefaultPropertyTrackingMode(Qt3DCore::QNode::PropertyTrackingMode mode)

Notifier signal:

void defaultPropertyTrackingModeChanged(Qt3DCore::QNode::PropertyTrackingMode mode)

enabled : bool

Holds the QNode enabled flag. By default a QNode is always enabled.

Note: the interpretation of what enabled means is aspect-dependent. Even if enabled is set to false, some aspects may still consider the node in some manner. This is documented on a class by class basis.

Access functions:

bool isEnabled() const
void setEnabled(bool isEnabled)

Notifier signal:

void enabledChanged(bool enabled)

parent : Qt3DCore::QNode*

Holds the immediate QNode parent, or null if the node has no parent.

Setting the parent will notify the backend aspects about current QNode instance's parent change.

Note: if parent happens to be null, this will actually notify that the current QNode instance was removed from the scene.

Access functions:

Qt3DCore::QNode *parentNode() const
void setParent(Qt3DCore::QNode *parent)

Notifier signal:

void parentChanged(QObject *parent)

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().

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)

void QNode::clearPropertyTrackings()

Qt3DCore::QNodeId QNode::id() const

Returns the id that uniquely identifies the QNode instance.

[signal] void QNode::nodeDestroyed()

Emitted when the node is destroyed.

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.

For the common case of a QObject property change, QNode handles this for you automatically by sending a QPropertyUpdatedChange event to the backend nodes. You only need to call this function if you wish to send a specific type of change in place of the automatic handling.

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

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 messages 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 performe 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)

See also propertyTracking().

Related Non-Members

typedef Qt3DCore::QNodePtr

A shared pointer for QNode.

typedef Qt3DCore::QNodeVector

List of QNode pointers.

Qt3DCore::QNodeId Qt3DCore::qIdForNode(Qt3DCore::QNode *node)

Returns node id for node.

Qt3DCore::QNodeIdVector Qt3DCore::qIdsForNodes(const T &nodes)

Returns vector of node ids for nodes.

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