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# SoVRMLVisibilitySensor Class Reference
[VRML97 classes]

`#include <Inventor/VRMLnodes/SoVRMLVisibilitySensor.h>`

Inheritance diagram for SoVRMLVisibilitySensor:

List of all members.

## Detailed Description

The SoVRMLVisibilitySensor class will generate events based on visibility.

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:

      VisibilitySensor {
        exposedField SFVec3f center   0 0 0      # (-,)
        exposedField SFBool  enabled  TRUE
        exposedField SFVec3f size     0 0 0      # [0,)
        eventOut     SFTime  enterTime
        eventOut     SFTime  exitTime
        eventOut     SFBool  isActive
      }

The VisibilitySensor node detects visibility changes of a rectangular box as the user navigates the world. VisibilitySensor is typically used to detect when the user can see a specific object or region in the scene in order to activate or deactivate some behaviour or animation. The purpose is often to attract the attention of the user or to improve performance.

The enabled field enables and disables the VisibilitySensor node. If enabled is set to FALSE, the VisibilitySensor node does not send events. If enabled is TRUE, the VisibilitySensor node detects changes to the visibility status of the box specified and sends events through the isActive eventOut. A TRUE event is output to isActive when any portion of the box impacts the rendered view. A FALSE event is sent when the box has no effect on the view. Browsers shall guarantee that, if isActive is FALSE, the box has absolutely no effect on the rendered view. Browsers may err liberally when isActive is TRUE. For example, the box may affect the rendering.

The exposed fields center and size specify the object space location of the box centre and the extents of the box (i.e., width, height, and depth). The VisibilitySensor node's box is affected by hierarchical transformations of its parents. The components of the size field shall be greater than or equal to zero.

The enterTime event is generated whenever the isActive TRUE event is generated, and exitTime events are generated whenever isActive FALSE events are generated. A VisibilitySensor read from a VRML file shall generate isActive TRUE and enterTime events if the sensor is enabled and the visibility box is visible. A VisibilitySensor inserted into the transformation hierarchy shall generate isActive TRUE and enterTime events if the sensor is enabled and the visibility box is visible. A VisibilitySensor removed from the transformation hierarchy shall generate isActive FALSE and exitTime events if the sensor is enabled and the visibility box is visible.

Each VisibilitySensor node behaves independently of all other VisibilitySensor nodes. Every enabled VisibilitySensor node that is affected by the user's movement receives and sends events, possibly resulting in multiple VisibilitySensor nodes receiving and sending events simultaneously. Unlike TouchSensor nodes, there is no notion of a VisibilitySensor node lower in the scene graph "grabbing" events. Multiply instanced VisibilitySensor nodes (i.e., DEF/USE) use the union of all the boxes defined by their instances. An instanced VisibilitySensor node shall detect visibility changes for all instances of the box and send events appropriately.

## Public Member Functions
| SoVRMLVisibilitySensor (void)
virtual void | GLRender (SoGLRenderAction *action)
## Static Public Member Functions
void | initClass (void)
## Public Attributes
SoSFVec3f | center
SoSFVec3f | size
SoSFBool | enabled
## Protected Member Functions
virtual | ~SoVRMLVisibilitySensor ()
## Protected Attributes
SoSFTime | enterTime
SoSFTime | exitTime
SoSFBool | isActive

## Constructor & Destructor Documentation

SoVRMLVisibilitySensor::SoVRMLVisibilitySensor | ( | void |  | ) |

| Constructor.

SoVRMLVisibilitySensor::~SoVRMLVisibilitySensor | ( |  | ) | `[protected, virtual]`

| Destructor.

## Member Function Documentation

void SoVRMLVisibilitySensor::initClass | ( | void |  | ) | `[static]`

| Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system. Reimplemented from SoNode.

void SoVRMLVisibilitySensor::GLRender | ( | SoGLRenderAction * | action | ) | `[virtual]`

| Action method for the SoGLRenderAction. This is called during rendering traversals. Nodes influencing the rendering state in any way or who wants to throw geometry primitives at OpenGL overrides this method. Reimplemented from SoNode.

## Member Data Documentation

SoSFVec3f SoVRMLVisibilitySensor::center

| Visibility area center. Default value is (0, 0, 0).

SoSFVec3f SoVRMLVisibilitySensor::size

| Visibility area size. Default value is (0, 0, 0).

SoSFBool SoVRMLVisibilitySensor::enabled

| Enable/disable sensor. Default value is TRUE.

SoSFTime SoVRMLVisibilitySensor::enterTime`[protected]`

| An event out that is triggered when the region becomes visible.

SoSFTime SoVRMLVisibilitySensor::exitTime`[protected]`

| An event out that is triggered when the region becomes not visible.

SoSFBool SoVRMLVisibilitySensor::isActive`[protected]`

| An event out that is generated when the visibility state changes.

The documentation for this class was generated from the following files:

- SoVRMLVisibilitySensor.h
- VisibilitySensor.cpp