javax.media.j3d
Interface InputDevice

public interface InputDevice

InputDevice is the interface through which Java 3D and Java 3D application programs communicate with a device driver. All input devices that Java 3D uses must implement the InputDevice interface and be registered with Java 3D via a call to PhysicalEnvironment.addInputDevice(InputDevice). An input device transfers information to the Java 3D implementation and Java 3D applications by writing transform information to sensors that the device driver has created and manages. The driver can update its sensor information each time the pollAndProcessInput method is called.

Version:

1.26, 02/04/01 14:56:33

Field Summary

static int	BLOCKING Signifies that the driver for a device is a blocking driver and that it should be scheduled for regular reads by Java 3D.
static int	DEMAND_DRIVEN Signifies that the Java 3D implementation should not schedule regular reads on the sensors of this device; the Java 3D implementation will only call pollAndProcessInput when one of the device's sensors' getRead methods is called.
static int	NON_BLOCKING Signifies that the driver for a device is a non-blocking driver and that it should be scheduled for regular reads by Java 3D.

Method Summary

void	close() Code to process the clean up of the device and relinquish associated resources.
int	getProcessingMode() This method retrieves the device's processing mode: one of BLOCKING, NON_BLOCKING, or DEMAND_DRIVEN.
Sensor	getSensor(int sensorIndex) Gets the specified Sensor associated with the device.
int	getSensorCount() This method gets the number of sensors associated with the device.
boolean	initialize() This method initializes the device.
void	pollAndProcessInput() This method causes the device's sensor readings to be updated by the device driver.
void	processStreamInput() This method will not be called by the Java 3D implementation and should be implemented as an empty method.
void	setNominalPositionAndOrientation() This method sets the device's current position and orientation as the devices nominal position and orientation (establish its reference frame relative to the "Tracker base" reference frame).
void	setProcessingMode(int mode) This method sets the device's processing mode to one of: BLOCKING, NON_BLOCKING, or DEMAND_DRIVEN.

Field Detail

BLOCKING

public static final int BLOCKING

Signifies that the driver for a device is a blocking driver and that it should be scheduled for regular reads by Java 3D. A blocking driver is defined as a driver that can cause the thread accessing the driver (the Java 3D implementation thread calling the pollAndProcessInput method) to block while the data is being accessed from the driver.

See Also:

Constant Field Values

NON_BLOCKING

public static final int NON_BLOCKING

Signifies that the driver for a device is a non-blocking driver and that it should be scheduled for regular reads by Java 3D. A non-blocking driver is defined as a driver that does not cause the calling thread to block while data is being retrieved from the driver. If no data is available from the device, pollAndProcessInput should return without updating the sensor read value.

See Also:

Constant Field Values

DEMAND_DRIVEN

public static final int DEMAND_DRIVEN

Signifies that the Java 3D implementation should not schedule regular reads on the sensors of this device; the Java 3D implementation will only call pollAndProcessInput when one of the device's sensors' getRead methods is called. A DEMAND_DRIVEN driver must always provide the current value of the sensor on demand whenever pollAndProcessInput is called. This means that DEMAND_DRIVEN drivers are non-blocking by definition.

See Also:

Constant Field Values

Method Detail

initialize

public boolean initialize()

This method initializes the device. A device should be initialized before it is registered with Java 3D via the PhysicalEnvironment.addInputDevice(InputDevice) method call.

Returns:

return true for succesful initialization, false for failure

setNominalPositionAndOrientation

public void setNominalPositionAndOrientation()

This method sets the device's current position and orientation as the devices nominal position and orientation (establish its reference frame relative to the "Tracker base" reference frame).

pollAndProcessInput

public void pollAndProcessInput()

This method causes the device's sensor readings to be updated by the device driver. For BLOCKING and NON_BLOCKING drivers, this method is called regularly and the Java 3D implementation can cache the sensor values. For DEMAND_DRIVEN drivers this method is called each time one of the Sensor.getRead methods is called, and is not otherwise called.

processStreamInput

public void processStreamInput()

This method will not be called by the Java 3D implementation and should be implemented as an empty method.

close

public void close()

Code to process the clean up of the device and relinquish associated resources. This method should be called after the device has been unregistered from Java 3D via the PhysicalEnvironment.removeInputDevice(InputDevice) method call.

getProcessingMode

public int getProcessingMode()

This method retrieves the device's processing mode: one of BLOCKING, NON_BLOCKING, or DEMAND_DRIVEN. The Java 3D implementation calls this method when PhysicalEnvironment.addInputDevice(InputDevice) is called to register the device with Java 3D. If this method returns any value other than BLOCKING, NON_BLOCKING, or DEMAND_DRIVEN, addInputDevice will throw an IllegalArgumentException.

Returns:

Returns the devices processing mode, one of BLOCKING, NON_BLOCKING, or DEMAND_DRIVEN

setProcessingMode

public void setProcessingMode(int mode)

This method sets the device's processing mode to one of: BLOCKING, NON_BLOCKING, or DEMAND_DRIVEN. Many drivers will be written to run in only one mode. Applications using such drivers should not attempt to set the processing mode. This method should throw an IllegalArgumentException if there is an attempt to set the processing mode to anything other than the aforementioned three values.

NOTE: this method should not be called after the input device has been added to a PhysicalEnvironment. The processingMode must remain constant while a device is attached to a PhysicalEnvironment.

Parameters:

mode - One of BLOCKING, NON_BLOCKING, or DEMAND_DRIVEN

getSensorCount

public int getSensorCount()

This method gets the number of sensors associated with the device.

Returns:

the device's sensor count.

getSensor

public Sensor getSensor(int sensorIndex)

Gets the specified Sensor associated with the device. Each InputDevice implementation is responsible for creating and managing its own set of sensors. The sensor indices begin at zero and end at number of sensors minus one. Each sensor should have had Sensor.setDevice(InputDevice) set properly before addInputDevice is called.

Parameters:

sensorIndex - the sensor to retrieve

Returns:

Returns the specified sensor.