# SoVRMLFog Class Reference
[VRML97 classes]

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

Inheritance diagram for SoVRMLFog:

List of all members.

## Detailed Description

The SoVRMLFog class is used to specify a global scene fog.

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:

      Fog {
        exposedField SFColor  color            1 1 1      # [0,1]
        exposedField SFString fogType          "LINEAR"
        exposedField SFFloat  visibilityRange  0          # [0,inf)
        eventIn      SFBool   set_bind
        eventOut     SFBool   isBound
      }

The Fog node provides a way to simulate atmospheric effects by blending objects with the colour specified by the color field based on the distances of the various objects from the viewer. The distances are calculated in the coordinate space of the Fog node. The visibilityRange specifies the distance in metres (in the local coordinate system) at which objects are totally obscured by the fog. Objects located outside the visibilityRange from the viewer are drawn with a constant colour of color. Objects very close to the viewer are blended very little with the fog color.

A visibilityRange of 0.0 disables the Fog node. The visibilityRange is affected by the scaling transformations of the Fog node's parents; translations and rotations have no affect on visibilityRange. Values of the visibilityRange field shall be in the range [0, ).

Since Fog nodes are bindable children nodes (see 4.6.10, Bindable children nodes http://www.web3d.org/technicalinfo/specifications/vrml97/part1/concepts.html#4.6.10), a Fog node stack exists, in which the top- most Fog node on the stack is currently active. To push a Fog node onto the top of the stack, a TRUE value is sent to the set_bind eventIn. Once active, the Fog node is bound to the browser view. A FALSE value sent to set_bind, pops the Fog node from the stack and unbinds it from the browser viewer. More details on the Fog node stack can be found in 4.6.10, Bindable children nodes (<http://www.web3d.org/technicalinfo/specifications/vrml97/part1/concepts.html#4.6.10>).

The fogType field controls how much of the fog colour is blended with the object as a function of distance. If fogType is "LINEAR", the amount of blending is a linear function of the distance, resulting in a depth cueing effect. If fogType is "EXPONENTIAL," an exponential increase in blending is used, resulting in a more natural fog appearance. The effect of fog on lighting calculations is described in 4.14, Lighting model (<http://www.web3d.org/technicalinfo/specifications/vrml97/part1/concepts.html#4.6.14>).

## Public Member Functions

| SoVRMLFog (void)
virtual void | GLRender (SoGLRenderAction *action)

## Static Public Member Functions

void | initClass (void)

## Public Attributes

SoSFString | fogType
SoSFFloat | visibilityRange
SoSFColor | color

## Protected Member Functions

virtual | ~SoVRMLFog ()

## Protected Attributes

SoSFBool | set_bind
SoSFBool | isBound

## Constructor & Destructor Documentation

SoVRMLFog::SoVRMLFog | ( | void |  | ) |

| Constructor.

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

| Destructor.

## Member Function Documentation

void SoVRMLFog::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 SoVRMLFog::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

SoSFString SoVRMLFog::fogType

| Type of fog. Can be either "LINEAR" or "EXPONENTIAL". Default value is "LINEAR".

SoSFFloat SoVRMLFog::visibilityRange

| Range of visibility. The distance when only the fog color can be seen. Default value is (0.0).

SoSFColor SoVRMLFog::color

| The fog color. Default value is (1, 1, 1).

SoSFBool SoVRMLFog::set_bind `[protected]`

| An eventIn that is used to bind this node (make the node active).

SoSFBool SoVRMLFog::isBound `[protected]`

| An eventOut that is sent when the node is bound/unbound.

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

- SoVRMLFog.h
- Fog.cpp