This node specifies a user position and parameters. In most cases, only a single unnamed user is necessary. However, in more general cases, it is possible to assign Users to specific Viewports to provide a more fine-grained control over the rendering that occurs in that viewport.

Attributes

name special [ string ]

Specifies the name of this user. Each user needs to have a unique name, but there also has to be exactly one user present that has an empty name (or without a name attribute) which is used as the default user.

eyeSeparation optional [ float >= 0 ]

Determines the eye separation used for stereoscopic viewports. If no viewports in the configuration are using stereo, this setting is ignored.

Children

Pos [ 0 - 1 ]

A linear offset of the user position. Must define three float attributes x, y, and z. The default values are x=0, y=0, z=0, meaning that no linear offset is applied to the user’s position.

Orientation [ 0 - 1 ]

Describes a fixed orientation for the viewing direction of this user. This can be provided either as Euler angles or as a quaternion. The two modes cannot be mixed. The following descibes the different attributes that can be used for the orientation. Please note that all attributes for the chosen method have to be specified. If the Matrix attribute is also specified, it will overwrite the value specified here.

Euler angles:

• pitch or elevation: negative numbers tilt the camera downwards; positive numbers tilt upwards. The allowed range is [-90, 90].
• yaw, heading, or azimuth: negative numbers pan the camera to the left; positive numbers pan to the right. The allowed range is [-360, 360].
• roll or bank: negative numbers rotate the camera to the left; positive numbers to the right. The allowed range is [-180, 180].

Quaternion:

• x
• y
• z
• w

Example: <Orientation pitch="20.0" elevation="-12.0" roll="0.0" />

Matrix [ 0 - 1 ]

A generic transformation matrix that is applied to the orientation of this user. This value will overwrite the value specified in Orientation. The attributes used for the matrix are named x0, y0, z0, w0, x1, y1, z1, w2, x2, y2, z2, w2, x3, y3, z3, w3 and are used in this order to initialize the matrix in a column-major order. All 16 of these values have to be present in this attribute and have to be floating point values.

transpose optional [ boolean ]

If this value is present and true the values provided are interpreted as being in row-major order, rather than column-major order. The default is false, making the matrix column-major.

Tracking [ 0 - 1 ]

Provides information about whether this user should be tracked using a VRPN-based tracker. This child node contains two attributes with information about the tracker that this user should be associated with.

tracker [ string ]

The name of the tracker group that this user should be linked with. This name must be a name of a Tracker that is specified in this configuration.

device [ string ]

The name of the device in the tracker group that should be used to control the tracking for this user. The specified device has to be a Device that was specified in the Tracker tracker.

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