---
name: "sensors"
section: "3"
platform: "linux"
package: "libcoin80-doc"
version: "3.1.4~abc9f50-7"
release: "Debian 8 (Jessie)"
platforms: ["linux"]
url: "https://new.carta.tech/sensors/3"
---

# sensors(3)

## NAME

Sensor Classes -

### Classes

class **SoAlarmSensor**\
 *The* **SoAlarmSensor** *class is a sensor which will trigger once at a specified time.*

**SoAlarmSensor** provides a convenient way of setting up triggers for jobs which should be executed only once when they are scheduled. **"** class **SoDataSensor**\
 *The* **SoDataSensor** *class is the abstract base class for sensors monitoring changes in a scene graph.*

**If you need to know when a particular entity (as a field or a node) changes, subclasses of SoDataSensor can be used to monitor the entity and notify you when it changes. "** class **SoDelayQueueSensor**\
 *The* **SoDelayQueueSensor** *class is the abstract base class for priority scheduled sensors.*

**Delay queue sensors are invoked upon various events** *not* **related to time occurrences. See documentation of subclasses to see which types of events can be surveilled by the builtin sensor types.** *"* class **SoFieldSensor**\
 *The* **SoFieldSensor** *class detects changes to a field.*

*Attach a field to a sensor of this type to put it under surveillance, so you can act upon changes to the field.* **"** class **SoIdleSensor**\
 *The* **SoIdleSensor** *class is a sensor which will trigger as soon as the application is idle.*

**An SoIdleSensor differs from an SoOneShotSensor in that it will not trigger if the delay queue processing is occurring due to the delay queue timeout, but** *only* **when the application is idle.** *"* class **SoNodeSensor**\
 *The* **SoNodeSensor** *class detects changes to nodes.*

*Attach a node to a sensor of this type to put it under surveillance, so you can act upon changes to the node.* **"** class **SoOneShotSensor**\
 *The* **SoOneShotSensor** *class is a sensor which will trigger once.*

**Since SoOneShotSensor is a subclass of SoDelayQueueSensor, it will trigger as soon as either the run-time system is idle, or if it is continually busy it will trigger within a fixed amount of time (this is by default 1/12th of a second, see SoSensorManager::setDelaySensorTimeout()). "** class **SoPathSensor**\
 *The* **SoPathSensor** *class detects changes to paths.*

**If you need to know when a path changes (i.e. nodes in the path has been removed, or new nodes is added), use this sensor to get a notification. "** class **SoSensor**\
 *The* **SoSensor** *class is the abstract base class for all sensors.*

**Sensors is a mechanism in Coin for scheduling jobs to be run upon specific events. The events in question could be particular points in time, or changes to entities in the scene graph. "** class **SoSensorManager**\
 *The* **SoSensorManager** *class handles the sensor queues.*

**There are two major sensor types in Coin, 'delay' sensors and 'timer' sensors: "** class **SoTimerQueueSensor**\
 *The* **SoTimerQueueSensor** *class is the abstract base class for sensors triggering on certain timer events.*

**Timer sensors triggers upon specific points in time. "** class **SoTimerSensor**\
 *The* **SoTimerSensor** *class is a sensor which will trigger at given intervals.*

**Use sensors of this class when you want a job repeated at a certain interval, without explicitly needing to reschedule the sensor (i.e. SoTimerSensor automatically re-schedules itself after it has been triggered). "**

## Detailed Description

**Sensors are objects that monitor other objects for changes and invoke callbacks when changes occur.**

## Author

**Generated automatically by Doxygen for Coin from the source code.**