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VRPN Add-On

Virtual Reality Peripheral Network (VRPN) is a device-independent system for accessing virtual reality peripherals in VR applications. The VRPN system consists of programming interfaces for both the client application and the hardware drivers and a server application that communicates with the hardware devices. TheDTrack application often goes as a server application.

A Virtual Reality Peripheral Network (VRPN) plugin represents the client application which is connected to the server and used for receiving input data from different input devices (joysticks, 3D motion and orientation tracking sensors and so on) via the Network. The plugin is provided as an add-on.

For example, by using the VRPN plugin, you can implement an application that processes input data from ART controls.

See Also

  • VrpnAnalogDevice class
  • VrpnButtonDevice class
  • VrpnTackerDevice class
  • Samples on plugin usage:
    • data/samples/plugins/vrpn_client_00 that demonstrates receiving data from the FlyStick device and two sensors, tracking this device and a head. The data is presented as a text.
    • data/samples/plugins/vrpn_client_01 that demonstrates receiving data from the virtual FlyStick device and two sensors, tracking this device and a head, inside the UNIGINE scene.
    Notice
    The samples will be available if you add the VRPN plugin add-on to your project via UNIGINE SDK Browser.

Launching VRPN Plugin

Notice
Before launching the plugin, you should run a server application (it is usually DTrack) that receives input data from an input device. The VRPN plugin will connect to this server and receive data from it.

To use the VRPN plugin, you should perform the following:

  1. Install the VRPN plugin (available via UNIGINE SDK Browser in the Add-Ons section) and add it to your project (by clicking Configure Project -> Add-ons in the Projects section of UNIGINE SDK Browser).
  2. Specify the extern_plugin command line option on the application start-up:
    Shell commands
    main_x86 -extern_plugin "VrpnClient"

Implementing Application Using VRPN Plugin

When the VRPN plugin add-on is added and run, the following classes are added to UnigineScript:

  • VrpnAnalogDevice that receives data about input devices sticks.
  • VrpnButtonDevice that receives data about input devices buttons states.
  • VrpnTrackerDevice that receives about position, orientation, velocity and acceleration of tracked objects from 3D tracking sensors.
Notice
Each class can be instanced more than once.

When implementing an application using the plugin, instances of the classes listed above should be created on engine initialization.

Notice
The server address and the device name should be passed to constructors of the UnigineScript classes (VrpnAnalogDevice, VrpnButtonDevice, VrpnTrackerDevice) as follows: device_name@server_address.

For example, if the VRPN server is set on the PC via the DTrack application, the following should be passed: DTrack@localhost. If the server is set on another PC, instead of the localhost, you should specify the PC's IP address. Also you should call the update() method for each initialized device on engine update.

Source code (UnigineScript)
#ifdef HAS_VRPN_CLIENT

VrpnTrackerDevice tracker;
VrpnButtonDevice button;
VrpnAnalogDevice analog;

int init() {
	
	tracker = new VrpnTrackerDevice("DTrack@localhost");
	button = new VrpnButtonDevice("DTrack@localhost");
	analog = new VrpnAnalogDevice("DTrack@localhost");
	
	return 1;
}

int shutdown() {

	delete tracker;
	delete button;
	delete analog;
	
	return 1;
}

int update() {
	
	tracker.update();
	button.update();
	analog.update();
	
	return 1;
}

#else

int init() {
	log.warning("No VRPN plugin detected\n");
	return 1;
}

int shutdown() {
	return 1;
}

#endif
Last update: 2017-10-20