SoVRMLTimeSensors generate events as time passes. SoVRMLTimeSensors can be used to drive continuous simulations and animations, periodic activities (e.g., one per minute), and/or single occurrence events such as an alarm clock.

<font color="#0000FF">NOTE:</font> This class does not exist in Open Inventor 10.0 and later.

VRML97 SPECIFICATION

This section describes the expected behavior of the node in a conforming VRML97 browser application. In some cases, the application is responsible for implementing portions of the expected behavior. Open Inventor viewer classes and IVF classes implement some of the application behaviors.

This section may reference portions of the VRML97 specification that are not present in this help file. The complete VRML97 spec is available at http://www.web3d.org.

SoVRMLTimeSensors generate events as time passes. SoVRMLTimeSensors can be used to drive continuous simulations and animations, periodic activities (e.g., one per minute), and/or single occurrence events such as an alarm clock. SoVRMLTimeSensor discrete eventOuts include: isActive , which becomes true when the SoVRMLTimeSensor begins running, and false when it stops running, and cycleTime , a time event at startTime and at the beginning of each new cycle (useful for synchronization with other time-based objects). The remaining outputs generate continuous events and consist of fraction_changed , which is an SFFloat in the closed interval [0,1] representing the completed fraction of the current cycle, and time , an SFTime event specifying the absolute time for a given simulation tick.

If the enabled exposedField is true, the SoVRMLTimeSensor is enabled and may be running. If a set_enabled false event is received while the SoVRMLTimeSensor is running, then the sensor should evaluate and send all relevant outputs, send a false value for isActive, and disable itself. However, events on the exposedFields of the SoVRMLTimeSensor (such as set_startTime) are processed and their corresponding eventOuts ( startTime_changed) are sent regardless of the state of enabled. The remaining discussion assumes enabled is true.

The loop, startTime, and stopTime exposedFields, and the isActive eventOut and their affects on the SoVRMLTimeSensor node, are discussed in detail in the "Concepts - Time Dependent Nodes" section. The "cycle" of an SoVRMLTimeSensor lasts for cycleInterval seconds. The value of cycleInterval must be greater than 0 (a value less than or equal to 0 produces undefined results). Because the SoVRMLTimeSensor is more complex than the abstract SoVRMLTimeDep node and generates continuous eventOuts, some of the information in the "Time Dependent Nodes" section is repeated here.

A cycleTime eventOut can be used for synchronization purposes, e.g., sound with animation. The value of a cycleTime eventOut will be equal to the time at the beginning of the current cycle. A cycleTime eventOut is generated at the beginning of every cycle, including the cycle starting at startTime. The first cycleTime eventOut for an SoVRMLTimeSensor node can be used as an alarm (single pulse at a specified time).

When an SoVRMLTimeSensor becomes active it will generate an isActive = true event and begin generating time , fraction_changed, and cycleTime events, which may be routed to other nodes to drive animation or simulated behaviors - (see below for behavior at read time). The time event outputs the absolute time for a given tick of the SoVRMLTimeSensor (time fields and events represent the number of seconds since midnight GMT January 1, 1970). fraction_changed events output a floating point value in the closed interval [0, 1], where 0 corresponds to startTime and 1 corresponds to startTime + N*cycleInterval, where N = 1, 2, ... . That is, the time and fraction_changed eventOuts can be computed as:

   time = now
  f = fmod(now - startTime, cycleInterval)
  if (f == 0.0 && now > startTime)
  fraction_changed = 1.0
  else
  fraction_changed = f / cycleInterval

No guarantees are made with respect to how often an SoVRMLTimeSensor will generate time events, but an SoVRMLTimeSensor should generate events at least at every simulation tick. SoVRMLTimeSensors are guaranteed to generate final time and fraction_changed events. If loop is false, the final time event will be generated with a value of (startTime+cycleInterval) or stopTime (if stopTime > startTime), whichever value is less. If loop is true at the completion of every cycle, then the final event will be generated as evaluated at stopTime (if stopTime > startTime) or never.

An active SoVRMLTimeSensor ignores set_cycleInterval , and set_startTime events. An active SoVRMLTimeSensor also ignores set_stopTime events for set_stopTime < startTime. For example, if a set_startTime event is received while an SoVRMLTimeSensor is active, then that set_startTime event is ignored (the startTime field is not changed, and a startTime_changed eventOut is not generated). If an active SoVRMLTimeSensor receives a set_stopTime event that is less than now and greater than or equal to startTime, it behaves as if the stopTime requested is now and sends the final events based on now (note that stopTime is set as specified in the eventIn).

FILE FORMAT/DEFAULT

VRMLTimeSensor {

cycleInterval	1
enabled	true
loop	false
pauseTime	0
resumeTime	0
startTime	0
stopTime	0
metadata	NULL

}

EVENTS

eventIn

SoSFTime	set_cycleInterval
SoSFBool	set_enabled
SoSFBool	set_loop
SoSFTime	set_pauseTime (Note: Not implemented)
SoSFTime	set_resumeTime (Note: Not implemented)
SoSFTime	set_startTime
SoSFTime	set_stopTime
SoSFNode	set_metadata

eventOut

SoSFTime	cycleTime
SoSFFloat	fraction_changed
SoSFBool	isActive
SoSFBool	isPaused (Note: Not implemented)
SoSFTime	time
SoSFTime	cycleInterval_changed
SoSFBool	enabled_changed
SoSFBool	loop_changed
SoSFTime	pauseTime_changed (Note: Not implemented)
SoSFTime	resumeTime_changed (Note: Not implemented)
SoSFTime	startTime_changed
SoSFTime	stopTime_changed
SoSFTime	elapsedTime
SoSFNode	metadata_changed

Obsoletesince Open Inventor 9500 The VRML API is no longer supported. See section http://oivdoc95.vsg3d.com/content/compatibility-notes-4#Deprecation of the Reference Manual.

Reference