SoVRMLFog(3) The SoVRMLFog class is used to specify a global scene fog.


#include <Inventor/VRMLnodes/SoVRMLFog.h>

Inherits SoNode.

Public Member Functions

virtual SoType getTypeId (void) const

SoVRMLFog (void)

virtual void GLRender (SoGLRenderAction *action)

Static Public Member Functions

static SoType getClassTypeId (void)

static void initClass (void)

Public Attributes

SoSFString fogType

SoSFFloat visibilityRange

SoSFColor color

Protected Member Functions

virtual const SoFieldData * getFieldData (void) const

virtual ~SoVRMLFog ()

Static Protected Member Functions

static const SoFieldData ** getFieldDataPtr (void)

Protected Attributes

SoSFBool set_bind

SoSFBool isBound

Additional Inherited 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, 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 (
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 ( 

Constructor & Destructor Documentation

SoVRMLFog::SoVRMLFog (void)


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


Member Function Documentation

SoType SoVRMLFog::getClassTypeId (void) [static]

This static method returns the SoType object associated with objects of this class.

Reimplemented from SoNode.

SoType SoVRMLFog::getTypeId (void) const [virtual]

Returns the type identification of an object derived from a class inheriting SoBase. This is used for run-time type checking and 'downward' casting.

Usage example:

  void foo(SoNode * node)
    if (node->getTypeId() == SoFile::getClassTypeId()) {
      SoFile * filenode = (SoFile *)node;  // safe downward cast, knows the type

For application programmers wanting to extend the library with new nodes, engines, nodekits, draggers or others: this method needs to be overridden in all subclasses. This is typically done as part of setting up the full type system for extension classes, which is usually accomplished by using the pre-defined macros available through for instance Inventor/nodes/SoSubNode.h (SO_NODE_INIT_CLASS and SO_NODE_CONSTRUCTOR for node classes), Inventor/engines/SoSubEngine.h (for engine classes) and so on.

For more information on writing Coin extensions, see the class documentation of the toplevel superclasses for the various class groups.

Implements SoBase.

const SoFieldData ** SoVRMLFog::getFieldDataPtr (void) [static], [protected]

This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

Reimplemented from SoNode.

const SoFieldData * SoVRMLFog::getFieldData (void) const [protected], [virtual]

Returns a pointer to the class-wide field data storage object for this instance. If no fields are present, returns NULL.

Reimplemented from SoFieldContainer.

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.


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