Dragging Sensors

Dragging sensors are a special kind of sensors that not only track users motion but also move the objects within the same group as the sensor. There are three type of dragging sensors:

PlaneSensor: lets the user move objects in the XY plane.

CylinderSensor: Maps the movement to the surface of a conceptual cylinder.

SphereSensor: Maps the movement to the surface of a conceptual sphere.

The above sensors all share the following fields:

enabled defines the status of the sensor

offset indicates the initial position of the shapes within the group, a zero offset will mean that the shapes will be moved from their original position, whereas an offset different from zero will indicate that dragging starts at the original position plus the specified offset. The offset value is ignored if autoOffset is TRUE. Note that the type of the offset field varies with the type of the sensor.

autoOffset specifies if the browser should track the current position or do all dragging operations relative to the original position. Only relevant for the second and subsequent draggings. If autoOffset is TRUE then the second dragging will start where the first one ended, if FALSE then the shapes will return to their original position each time a new dragging operation begins.

The following events are common to all the sensors:

isActive indicates whether a dragging operation is being done. The isActive will output TRUE if the user has the mouse pressed over a shape within the same group as the sensor, and FALSE otherwise.

trackPoint_changed provides the actual coordinates in the surface defined by the sensor

rotation_changed (SphereSensor and CylinderSensor) and translation_changed (PlaneSensor) provides the relative orientation or translation being made.

In order to actually move the shapes you should place the shapes inside a Transform node. The Transform node should be in the same group as the sensor. You then need to route this events to fields in a Transform group. See the examples provided for each sensor.

If using multiple sensors in the same group it is up to you to specify which does what, they will all generate events when any of the shapes within the group is affected.

If using multiple drag sensors in nested groups then the inner group sensors grab the users action and the outer group sensors will ignore it.