Sensors can be thought of in two categories, those associated with geometry and one for sensing time.
The list of sensors is :
* CylinderSensor
* PlaneSensor
* ProximitySensor
* SphereSensor
* TouchSensor
* VisibilitySensor
* TimeSensor
The sensors can respond to various conditions such as proximity to an avatar,mouse clicks, mouse movement or whether an object is in the field of view of the user.
In addition, cylinder, sphere and plane sensors move the geometry associated with them when they are active.
Do not place a sensor in the same transform node as the geometry as this can result in undefined behaviour
