trusty (3) SoVRMLTimeSensor.3.gz
NAME
SoVRMLTimeSensor -
The SoVRMLTimeSensor class is a multi-purpose time event generator.
The detailed class documentation is taken verbatim from the VRML97 standard (ISO/IEC 14772-1:1997). It is
copyright The Web3D Consortium, and is used by permission of the Consortium:
SYNOPSIS
#include <Inventor/VRMLnodes/SoVRMLTimeSensor.h>
Inherits SoNodeEngine.
Public Member Functions
virtual SoType getTypeId (void) const
Returns the type identification of an object derived from a class inheriting SoBase. This is used for
run-time type checking and 'downward' casting.
virtual const SoEngineOutputData * getOutputData (void) const
SoVRMLTimeSensor (void)
virtual void notify (SoNotList *list)
virtual void handleEvent (SoHandleEventAction *action)
virtual void write (SoWriteAction *action)
Static Public Member Functions
static SoType getClassTypeId (void)
static void * createInstance (void)
static void initClass (void)
Public Attributes
SoSFTime cycleInterval
SoSFBool enabled
SoSFBool loop
SoSFTime startTime
SoSFTime stopTime
SoEngineOutput cycleTime
SoEngineOutput fraction_changed
SoEngineOutput isActive
SoEngineOutput time
Protected Member Functions
virtual const SoFieldData * getFieldData (void) const
virtual ~SoVRMLTimeSensor ()
virtual void inputChanged (SoField *whichInput)
Static Protected Member Functions
static const SoFieldData ** getFieldDataPtr (void)
static const SoEngineOutputData ** getOutputDataPtr (void)
Additional Inherited Members
Detailed Description
The SoVRMLTimeSensor class is a multi-purpose time event generator.
The detailed class documentation is taken verbatim from the VRML97 standard (ISO/IEC 14772-1:1997). It is
copyright The Web3D Consortium, and is used by permission of the Consortium:
TimeSensor {
exposedField SFTime cycleInterval 1 # (0,inf)
exposedField SFBool enabled TRUE
exposedField SFBool loop FALSE
exposedField SFTime startTime 0 # (-inf,inf)
exposedField SFTime stopTime 0 # (-inf,inf)
eventOut SFTime cycleTime
eventOut SFFloat fraction_changed # [0, 1]
eventOut SFBool isActive
eventOut SFTime time
}
TimeSensor nodes generate events as time passes. TimeSensor nodes can be used for many purposes
including:
• driving continuous simulations and animations;
• controlling periodic activities (e.g., one per minute);
• initiating single occurrence events such as an alarm clock.
The TimeSensor node contains two discrete eventOuts: isActive and cycleTime. The isActive eventOut sends
TRUE when the TimeSensor node begins running, and FALSE when it stops running. The cycleTime eventOut
sends a time event at startTime and at the beginning of each new cycle (useful for synchronization with
other time-based objects). The remaining eventOuts generate continuous events. The fraction_changed
eventOut, an SFFloat in the closed interval [0,1], sends the completed fraction of the current cycle. The
time eventOut sends the absolute time for a given simulation tick.
If the enabled exposedField is TRUE, the TimeSensor node is enabled and may be running. If a set_enabled
FALSE event is received while the TimeSensor node is running, the sensor performs the following actions:
• evaluates and sends all relevant outputs;
• sends a FALSE value for isActive;
• disables itself.
Events on the exposedFields of the TimeSensor node (e.g., set_startTime) are processed and their
corresponding eventOuts (e.g., startTime_changed) are sent regardless of the state of the enabled field.
The remaining discussion assumes enabled is TRUE.
The e\ loop, startTime, and stopTime exposedFields and the isActive eventOut and their effects on the
TimeSensor node are discussed in detail in 4.6.9, Time-dependent nodes
(http://www.web3d.org/x3d/specifications/vrml/ISO-IEC-14772-VRML97/part1/concepts.html#4.6.9). The
'cycle' of a TimeSensor node lasts for cycleInterval seconds. The value of cycleInterval shall be greater
than zero.
A cycleTime eventOut can be used for synchronization purposes such as 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 a TimeSensor node can be used as an alarm (single pulse at a specified
time).
When a TimeSensor node becomes active, it generates an isActive = TRUE event and begins generating time,
fraction_changed, and cycleTime events which may be routed to other nodes to drive animation or simulated
behaviours. The behaviour at read time is described below. The time event sends the absolute time for a
given tick of the TimeSensor node (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]. At startTime the
value of fraction_changed is 0. After startTime, the value of fraction_changed in any cycle will progress
through the range (0.0, 1.0]. At startTime + N cycleInterval, for N = 1, 2, ..., that is, at the end of
every cycle, the value of fraction_changed is 1.
Let now represent the time at the current simulation tick. Then the time and fraction_changed eventOuts
can then be computed as:
time = now
temp = (now - startTime) / cycleInterval
f = fractionalPart(temp)
if (f == 0.0 && now > startTime) fraction_changed = 1.0
else fraction_changed = f
where fractionalPart(x) is a function that returns the fractional part, (that is, the digits to the right
of the decimal point), of a nonnegative floating point number.
A TimeSensor node can be set up to be active at read time by specifying loop TRUE (not the default) and
stopTime less than or equal to startTime (satisfied by the default values). The time events output
absolute times for each tick of the TimeSensor node simulation. The time events shall start at the first
simulation tick greater than or equal to startTime. time events end at stopTime, or at startTime + N
cycleInterval for some positive integer value of N, or loop forever depending on the values of the other
fields. An active TimeSensor node shall stop at the first simulation tick when now >= stopTime >
startTime.
No guarantees are made with respect to how often a TimeSensor node generates time events, but a
TimeSensor node shall generate events at least at every simulation tick. TimeSensor nodes are guaranteed
to generate final time and fraction_changed events. If loop is FALSE at the end of the Nth cycleInterval
and was TRUE at startTime + M cycleInterval for all 0 < M < N, the final time event will be generated
with a value of (startTime + N cycleInterval) or stopTime (if stopTime > startTime), whichever value is
less. If loop is TRUE at the completion of every cycle, the final event is generated as evaluated at
stopTime (if stopTime > startTime) or never.
An active TimeSensor node ignores set_cycleInterval and set_startTime events. An active TimeSensor node
also ignores set_stopTime events for set_stopTime less than or equal to startTime. For example, if a
set_startTime event is received while a TimeSensor node is active, that set_startTime event is ignored
(the startTime field is not changed, and a startTime_changed eventOut is not generated). If an active
TimeSensor node receives a set_stopTime event that is less than the current time, and greater than
startTime, it behaves as if the stopTime requested is the current time and sends the final events based
on the current time (note that stopTime is set as specified in the eventIn).
A TimeSensor read from a VRML file shall generate isActive TRUE, time and fraction_changed events if the
sensor is enabled and all conditions for a TimeSensor to be active are met.
Constructor & Destructor Documentation
SoVRMLTimeSensor::SoVRMLTimeSensor (void)
Constructor.
SoVRMLTimeSensor::~SoVRMLTimeSensor () [protected], [virtual]
Destructor.
Member Function Documentation
SoType SoVRMLTimeSensor::getTypeId (void) const [virtual]
Returns the type identification of an object derived from a class inheriting SoBase. This is used for
run-time type checking and 'downward' casting. Usage example:
void foo(SoNode * node)
{
if (node->getTypeId() == SoFile::getClassTypeId()) {
SoFile * filenode = (SoFile *)node; // safe downward cast, knows the type
}
}
For application programmers wanting to extend the library with new nodes, engines, nodekits, draggers or
others: this method needs to be overridden in all subclasses. This is typically done as part of setting
up the full type system for extension classes, which is usually accomplished by using the pre-defined
macros available through for instance Inventor/nodes/SoSubNode.h (SO_NODE_INIT_CLASS and
SO_NODE_CONSTRUCTOR for node classes), Inventor/engines/SoSubEngine.h (for engine classes) and so on.
For more information on writing Coin extensions, see the class documentation of the toplevel superclasses
for the various class groups.
Implements SoBase.
const SoFieldData * SoVRMLTimeSensor::getFieldData (void) const [protected], [virtual]
Returns a pointer to the class-wide field data storage object for this instance. If no fields are
present, returns NULL.
Reimplemented from SoFieldContainer.
const SoEngineOutputData * SoVRMLTimeSensor::getOutputData (void) const [virtual]
This API member is considered internal to the library, as it is not likely to be of interest to the
application programmer.
Implements SoNodeEngine.
void SoVRMLTimeSensor::notify (SoNotList *l) [virtual]
Notifies all auditors for this instance when changes are made.
Reimplemented from SoNodeEngine.
void SoVRMLTimeSensor::handleEvent (SoHandleEventAction *action) [virtual]
Action method for SoHandleEventAction.
Inspects the event data from action, and processes it if it is something which this node should react to.
Nodes influencing relevant state variables for how event handling is done also overrides this method.
Reimplemented from SoNode.
void SoVRMLTimeSensor::write (SoWriteAction *action) [virtual]
Action method for SoWriteAction.
Writes out a node object, and any connected nodes, engines etc, if necessary.
Reimplemented from SoNode.
void SoVRMLTimeSensor::inputChanged (SoField *which) [protected], [virtual]
Called when an input is changed. The default method does nothing, but subclasses may override this method
to do the The Right Thing when a specific field is changed.
Reimplemented from SoNodeEngine.
Member Data Documentation
SoSFTime SoVRMLTimeSensor::cycleInterval
The cycle interval. Default value is 1. Must be > 0.
SoSFBool SoVRMLTimeSensor::enabled
Used to enable/disable timer. Default value is TRUE.
SoSFBool SoVRMLTimeSensor::loop
TRUE if timer should loop. Default value is FALSE.
SoSFTime SoVRMLTimeSensor::startTime
The timer start time. Default value is 0.0.
SoSFTime SoVRMLTimeSensor::stopTime
The timer stop time. Default value is 0.0.
SoEngineOutput SoVRMLTimeSensor::cycleTime
An eventOut that is sent when a new cycle is started.
SoEngineOutput SoVRMLTimeSensor::fraction_changed
An eventOut that is sent for each tick, containing a number between 0 and 1.
SoEngineOutput SoVRMLTimeSensor::isActive
An eventOut that is sent when the timer is enabled/disabled.
SoEngineOutput SoVRMLTimeSensor::time
An eventOut that is sent for each tick, containing the current time.
Author
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