Virtual Reality Private Network (VRPN)

VRPN is a protocol used in Virtual Reality to exchange data with external devices. See http://www.cs.unc.edu/Research/vrpn/.

BlenderVR behaves like a VRPN client. At the other end, a VRPN server will host different tracker or sensors that would be as many haptic arms, tracked stereoscopic glasses or Wiimote devices. The server will associate a name to these device, along with a variable “info” that holds the useful information about the considered device.

In BlenderVR, the receiving of VRPN messages and definition of associated methods is done in the <blender_scene_name>.processor.py script attached to a scene (see examples in the samples folder).

Document Sections

• Interaction Setup
• Example with a Nintendo Wii Controller

Interaction Setup

To be able to interact in your BlenderVR scene with a VRPN compatible interface you will have to:

1. Define the interface in your vprn.cfg script
2. Define the related processor method in the BlenderVR .xml configuration script
3. Define the processor method in the <blender_scene_name>.processor.py script attached to your BlenderVR scene

Example with a Nintendo Wii Controller

1. In your vrpn.cfg file, add:

vrpn_WiiMote WiiMote0 1 0 0 1

2. In the BlenderVR .xml configuration script (e.g. single.xml), add:

<processor>
  (...)
  <plugins>
    <vrpn>
      <analog device="WiiMote0" host="localhost" processor_method="wiiAnalog"/>
      <button device="WiiMote0" host="localhost" processor_method="wiiButton"/>
    </vrpn>
  </plugins>
</processor>

Analog will receive accelerometer data from the WiiMote, button only the pressed button states.

Note

You also need to specify the folder containing your vrpn library in the configuration file.

3. In the <blend_file_name>.processor.py script (e.g. BlenderVR_API.processor.py), add:

import blendervr

if blendervr.is_virtual_environment():
  import bge

  class Processor(blendervr.processor.getProcessor()):
    (...)

    def wiiAnalog(self, info):
      self.logger.info("Analog from Wii through VPRN ", info)

    def wiiButton(self, info):
      self.logger.info("Button from Wii through VPRN ", info)

Here, both functions will be executed whenever the VRPN server receives data from the WiiMote (the wiiButton when your touch a button, the wiiAnalog when you move the WiiMote).