quaternion QML Value Type

This represents an orientation in free space in quaternion form. More...

Properties

• eulerAngles : vector3d
• rpy : vector3
• rpyDegrees : vector3
• scalar : double
• w : double
• x : double
• y : double
• z : double

Methods

• QQuaternion toQuaternion()

Detailed Description

quaternion is a structured value type usable in QML. It maps directly to the geometry_msgs::msg::Quaternion ROS 2 message type.

Similar to QtQuick's quaternion value type but stored as four double components (x, y, z, w) rather than float, matching the ROS 2 wire format. Use toQuaternion() / fromQuaternion to bridge to quaternion when its math API (slerp, normalize, multiplication) is needed.

A literal value is a JavaScript object such as ({ x: 0, y: 0, z: 0, w: 1 }) (w defaults to 1). The Quaternion helper's fromEulerAngles takes ROS roll/pitch/yaw (about X/Y/Z, Z-up) in degrees; do not use QtQuick3D's Quaternion, whose argument order is pitch/yaw/roll in a Y-up frame, or the axes come out wrong when published to ROS.

Construct a quaternion in QML by assigning a JavaScript object whose keys are its component properties, by setting those properties individually, or by composing it with a factory function of the Quaternion helper type.

See also Quaternion, QuaternionPublisher, and QuaternionSubscriber.

Property Documentation

eulerAngles : vector3d

Orientation as Euler angles in degrees, as a vector3d.

Components are (x = roll about X, y = pitch about Y, z = yaw about Z) using the ROS Z-up axis convention. Single precision (QVector3D), for direct binding to Qt Quick 3D's eulerRotation.

See rpy for radians and rpyDegrees for degrees as a double-precision vector3 (usable without Qt Quick).

rpy : vector3

Orientation as roll/pitch/yaw in radians (ROS convention).

Components are (x = roll, y = pitch, z = yaw) in radians, as a double-precision vector3. This is the ROS-native form and, unlike eulerAngles, is usable from a QCoreApplication (it does not need the Qt Quick vector3d value type).

Precision may still degrade near gimbal singularities (pitch = ±90°).

rpyDegrees : vector3

Orientation as roll/pitch/yaw in degrees, as a vector3.

Components are (x = roll, y = pitch, z = yaw) in degrees, as a double-precision vector3. Like rpy (and unlike eulerAngles) it is usable without Qt Quick — convenient for a headless QCoreApplication consumer that works in degrees.

scalar : double

The scalar (real) component; an alias of w.

Lets a QtQuick quaternion assigned to this type map its scalar onto w (QML converts value types by name).

w : double

x : double

y : double

z : double

Method Documentation

QQuaternion toQuaternion()

Return a single-precision quaternion with the same orientation.

Useful for accessing quaternion's math API (slerp, normalize, multiplication).