SoVRMLSound -

#include <Inventor/VRMLnodes/SoVRMLSound.h>

Inherits SoNode.

The SoVRMLSound class is used to represent a sound source.

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:.

  Sound {
    exposedField SFVec3f  direction     0 0 1   # (-inf, inf)
    exposedField SFFloat  intensity     1       # [0,1]
    exposedField SFVec3f  location      0 0 0   # (-inf, inf)
    exposedField SFFloat  maxBack       10      # [0,inf)
    exposedField SFFloat  maxFront      10      # [0,inf)
    exposedField SFFloat  minBack       1       # [0,inf)
    exposedField SFFloat  minFront      1       # [0,inf)
    exposedField SFFloat  priority      0       # [0,1]
    exposedField SFNode   source        NULL
    field        SFBool   spatialize    TRUE
  }
  .fi


The Sound node specifies the spatial presentation of a sound in a VRML scene. The sound is located at a point in the local coordinate system and emits sound in an elliptical pattern (defined by two ellipsoids). The ellipsoids are oriented in a direction specified by the direction field. The shape of the ellipsoids may be modified to provide more or less directional focus from the location of the sound.

The source field specifies the sound source for the Sound node. If the source field is not specified, the Sound node will not emit audio. The source field shall specify either an AudioClip node or a MovieTexture node. If a MovieTexture node is specified as the sound source, the MovieTexture shall refer to a movie format that supports sound (e.g., MPEG1-Systems).

The intensity field adjusts the loudness (decibels) of the sound emitted by the Sound node (note: this is different from the traditional definition of intensity with respect to sound).

The intensity field has a value that ranges from 0.0 to 1.0 and specifies a factor which shall be used to scale the normalized sample data of the sound source during playback. A Sound node with an intensity of 1.0 shall emit audio at its maximum loudness (before attenuation), and a Sound node with an intensity of 0.0 shall emit no audio. Between these values, the loudness should increase linearly from a -20 dB change approaching an intensity of 0.0 to a 0 dB change at an intensity of 1.0.

The priority field provides a hint for the browser to choose which sounds to play when there are more active Sound nodes than can be played at once due to either limited system resources or system load. 7.3.4, Sound priority, attenuation, and spatialization (<http://www.web3d.org/x3d/specifications/vrml/ISO-IEC-14772-IS-VRML97WithAmendment1/part1/concepts.html#7.3.4>), describes a recommended algorithm for determining which sounds to play under such circumstances. The priority field ranges from 0.0 to 1.0, with 1.0 being the highest priority and 0.0 the lowest priority.

The location field determines the location of the sound emitter in the local coordinate system. A Sound node's output is audible only if it is part of the traversed scene. Sound nodes that are descended from LOD, Switch, or any grouping or prototype node that disables traversal (i.e., drawing) of its children are not audible unless they are traversed. If a Sound node is disabled by a Switch or LOD node, and later it becomes part of the traversal again, the sound shall resume where it would have been had it been playing continuously.

The Sound node has an inner ellipsoid that defines a volume of space in which the maximum level of the sound is audible. Within this ellipsoid, the normalized sample data is scaled by the intensity field and there is no attenuation. The inner ellipsoid is defined by extending the direction vector through the location.

The minBack and minFront fields specify distances behind and in front of the location along the direction vector respectively. The inner ellipsoid has one of its foci at location (the second focus is implicit) and intersects the direction vector at minBack and minFront. The Sound node has an outer ellipsoid that defines a volume of space that bounds the audibility of the sound. No sound can be heard outside of this outer ellipsoid.

The outer ellipsoid is defined by extending the direction vector through the location. The maxBack and maxFront fields specify distances behind and in front of the location along the direction vector respectively. The outer ellipsoid has one of its foci at location (the second focus is implicit) and intersects the direction vector at maxBack and maxFront. The minFront, maxFront, minBack, and maxBack fields are defined in local coordinates, and shall be greater than or equal to zero. The minBack field shall be less than or equal to maxBack, and minFront shall be less than or equal to maxFront. The ellipsoid parameters are specified in the local coordinate system but the ellipsoids' geometry is affected by ancestors' transformations.

Between the two ellipsoids, there shall be a linear attenuation ramp in loudness, from 0 dB at the minimum ellipsoid to -20 dB at the maximum ellipsoid: attenuation = -20 × (d' / d') where d' is the distance along the location-to-viewer vector, measured from the transformed minimum ellipsoid boundary to the viewer, and d' is the distance along the location-to-viewer vector from the transformed minimum ellipsoid boundary to the transformed maximum ellipsoid boundary (see Figure 6.14).

  Figure 6.14 -- Sound node geometry 

The spatialize field specifies if the sound is perceived as being directionally located relative to the viewer. If the spatialize field is TRUE and the viewer is located between the transformed inner and outer ellipsoids, the viewer's direction and the relative location of the Sound node should be taken into account during playback. Details outlining the minimum required spatialization functionality can be found in 7.3.4, Sound priority, attenuation, and spatialization (<http://www.web3d.org/x3d/specifications/vrml/ISO-IEC-14772-IS-VRML97WithAmendment1/part1/concepts.html#7.3.4>), If the spatialize field is FALSE, then directional effects are ignored, but the ellipsoid dimensions and intensity will still affect the loudness of the sound. If the sound source is multi-channel (e.g., stereo), then the source should retain its channel separation during playback. 

Public Member Functions

Static Public Member Functions

Public Attributes

Protected Member Functions

Static Protected Member Functions

Friends

SoVRMLSound::SoVRMLSound (void)

SoVRMLSound::~SoVRMLSound (void) [protected, virtual]

SoType SoVRMLSound::getClassTypeId (void) [static]

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

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

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

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

void SoVRMLSound::initClass (void) [static]

void SoVRMLSound::setDopplerVelocity (float velocity)

float SoVRMLSound::getDopplerVelocity ()

void SoVRMLSound::setDopplerFactor (float factor)

float SoVRMLSound::getDopplerFactor ()

void SoVRMLSound::startPlaying (SoPath * path, void * userdataptr)

void SoVRMLSound::stopPlaying (SoPath * path, void * userdataptr)

void SoVRMLSound::audioRender (SoAudioRenderAction * action) [virtual]

SoSFNode SoVRMLSound::source

SoSFFloat SoVRMLSound::intensity

SoSFFloat SoVRMLSound::priority

SoSFVec3f SoVRMLSound::location

SoSFVec3f SoVRMLSound::direction

SoSFFloat SoVRMLSound::minFront

SoSFFloat SoVRMLSound::maxFront

SoSFFloat SoVRMLSound::minBack

SoSFFloat SoVRMLSound::maxBack

SoSFBool SoVRMLSound::spatialize

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