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QNode Class

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

This class was introduced in Qt 5.5.

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QNode Class

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

See also QEntity, 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

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:

Notifier signal:

  • void defaultPropertyTrackingModeChanged( mode)

enabled : bool

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

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.

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

Access functions:

  • *parentNode() const

  • void setParent( *parent)

Notifier signal:

  • void parentChanged( *parent)

Member Function Documentation

 

[explicit] QNode::QNode(Qt3DCore::QNode *parent = nullptr)

Creates a new QNode instance with parent parent.

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

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

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.

Getter function for property defaultPropertyTrackingMode.

See Also

Qt3DCore::QNodeId QNode::id() const

Returns the id that uniquely identifies the QNode instance.

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

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

Returns the tracking mode of propertyName.

See Also

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.

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

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

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

Sets the property tracking for propertyName and trackMode.

See Also

See also propertyTracking()

Related Non-Members

 

QNodePtr

A shared pointer for QNode.

QNodeVector

List of QNode pointers.

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

Returns node id for node.

Qt3DCore::QNodeIdVector qIdsForNodes(const T &nodes)

Returns vector of node ids for nodes.

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