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David Rose
53 lines
2.4 KiB
Plaintext
53 lines
2.4 KiB
Plaintext
OVERVIEW
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The ClientBase class (and subsequent children) were created to
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solve the problem of interfaces to device API's that don't match up
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well with panda (especially the DataGraph), and to allow for threading
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of the polling of these devices in a manageable way.
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To use, simply create an instance of the particular client
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that you need. In most cases, this will be VrpnClient, when you
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create the client you will specify the name of the server that is
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controlling the devices.
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After you have created it, you can tell it to "add" whatever
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kind of device that you are interested in. When you do this it will
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setup the connection to that device and prepare itself to poll that
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device. (If you have asynchronous-clients $t in you config file, and
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call fork_asynchronous_thread(), then a thread will be created to
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continuously poll the device(s) in the background for you). Whenever
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you want, possibly, new data from the device simply call the
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appropriate get function.
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INTERFACE TO DATAGRAPH
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The interface to the data graph in panda is fairly simple, and
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best explained through an existing example. The DataGraph is
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traversed every frame, and each node in it, should defined as a
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sub-class of DataNode. Any sub-class of DataNode should have a method
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called transmit_data. Each traversal transmit_data will be called on
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each node. Those nodes will, if they are devices, package up their
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data and send it down the line to the next node, or, if they are
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tforms, take the incoming data, and put that data in some usable form
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on the scene graph. For Clients to fit in, a sub-class of DataNode
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should be defined that takes a pointer to a ClientBase object, and
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calls the appropriate add and get functions as necessary for whatever
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kind of device is appropriate.
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EXAMPLE
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TrackerNode inherits from DataNode and takes a ClientBase,
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tracker name and sensor number as paramaters at creation. On
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creation, it calls add_remote_tracker() on the Client object. When
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transmit_data() is called, it calls get_tracker_data() and sends that
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data down the line.
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TrackerTransform inherits from DataNode. When transmit_data()
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is called, it grabs the postion and orientation information as sent to
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it from a TrackerNode above it, and creates a matrix from that data
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and sends that matrix down the line.
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Transform2SG inherits from DataNode. When transmit_data() is
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called, it grabs the matrix as sent to it by some DataNode above it
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and stuffs that matrix onto a speficied arc in the SceneGraph.
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