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Subsections


Tracker Form

Figure 4.14: The Tracker form
\resizebox{3in}{!}{\includegraphics{pictures/ug_tracker2}}

The Tracker form is used to set up external 3D pointers, buttons, force-feedback devices, and the VMD ``tools'' that they control.

Supported devices and how to configure them

VMD currently can only communicate with devices in two ways: through the CAVE software or using the Virtual Reality Peripheral Network (VRPN). VRPN is a system which allows workstations to use many types of devices over the network. This means that VMD does not have to be running on the same computer that the devices are plugged into. In the CAVE, VMD recognizes two types of devices: buttons and three-dimensional trackers. With VRPN, you may use buttons, trackers, and also force-feedback (haptic) devices such as the PHANToM. More types of devices may be added in the future.

To use these kinds of devices with VMD, you need to create a sensor configuration file, in your home directory, called .vmdsensors. In this file, any number of devices can be specified, using a universal sensor locator (USL). The format for a USL is as follows:

The lines of a sensor configuration file come in four flavors:

Here is an example, showing all the possible things you can do with a sensor configuration file:

# the PHANToM connected to the computer "odessa"
device phantomtracker vrpntracker://odessa/Phantom0
scale 10
rot left 0 0 -1 0 1 0 1 0 0

device phantombuttons vrpnbuttons://odessa/Phantom0
device   phantomfeedback vrpnfeedback://odessa/Phantom0

# Polhemus fastrak on titan
device fastrak1 vrpntracker://titan/Tracker0:0
rot right 0 0 1 1 0 0 0 1 0
rot left 0 0 -1 -1 0 0 0 -1 0
device fastrak2 vrpntracker://titan/Tracker0:1
rot right 0 0 1 1 0 0 0 1 0
rot left 0 0 -1 -1 0 0 0 -1 0

#### Configuration for the CAVE
# CAVE tracker
device cavetracker cavetracker://cave/cave
scale 0.32
offset 0 -3.03 0

# CAVE buttons
device cavebuttons cavebuttons://cave/cave:0,1,2,3

# CAVE buttons (for left-handers)
device cavebuttons cavebuttons://cave/cave:3,2,1,0


Using devices with VMD

There are several different ``tools'', each of which can be used with any of the input devices4.1:

To add a new tool to a VMD session, open the tracker form and click the Create Tool button. The tool's number and type are displayed in the list to the left. Devices can be added to the tool by selecting them from the Add Device menu, or removed with the Delete Device button. Some of the options that can be specified in the sensor configuration file can be edited in using the controls below, and the tool's type can be changed with the Type menu.
next up previous contents index
Next: Sim Form Up: Description of each VMD Previous: Render Form   Contents   Index
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