The Add Attribute Gui example demonstrates the following:

• How to build a plugin module for the VR-Forces Gui
  • How to create a protocol dependent accessory and add GUI elements to it
  • How to extend a VR-Link state repository to include additional FOM level data
  • How to transfer the new VR-Link state repository data to the GUI thread using the extendedStateData

In order to incorporate a protocol-specific extension in the VR-Forces front-end, the VR-Vantage Accessories concept is used. An accessory is an external plugin that can be used in association with a particular application driver (scene, transport, etc). In the case of this example, a transport driver is used to extend functionality of the system, in this case the HLA13 and HLA1516 drivers.

When using accessories to extend the protocol-specific workings, it is important to note the following:

• The isCompatible method must be overriden to return "true" if the accessory is compatible with the supplied driver
  • The install method must be overriden so as to set up connections that send notifications when the driver has been connected
  • Similarly, the uninstall method must be overridden so that any connections made during the run of this plugin are disconnected

This accessory introduces the concept of the VR-Link state repository interceptor and the simulation data repository

The interceptor plays the role of capturing VR-Link information and sending out signals to notify developers when particular data members of the state repository have changed. While the signal is not specifically used in this example, the override is necessary to make sure that the extended state repository gets created when entities appear on the network.