/**************************************************************************\
 *
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 *  Copyright (C) 1998-2006 by Systems in Motion.  All rights reserved.
 *
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 *  ("GPL") version 2 as published by the Free Software Foundation.
 *  See the file LICENSE.GPL at the root directory of this source
 *  distribution for additional information about the GNU GPL.
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 *  GPL, and for taking advantage of the additional benefits of our
 *  support services, please contact Systems in Motion about acquiring
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 *
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 *
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\**************************************************************************/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif // HAVE_CONFIG_H

#ifdef HAVE_VRML97

/*!
  \class SoVRMLPositionInterpolator SoVRMLPositionInterpolator.h Inventor/VRMLnodes/SoVRMLPositionInterpolator.h
  \brief The SoVRMLPositionInterpolator class is used to interpolate 3D points.
  \ingroup VRMLnodes

  \WEB3DCOPYRIGHT

  \verbatim
  PositionInterpolator {
    eventIn      SFFloat set_fraction        # (-,)
    exposedField MFFloat key           []    # (-,)
    exposedField MFVec3f keyValue      []    # (-,)
    eventOut     SFVec3f value_changed
  }
  \endverbatim
  
  The PositionInterpolator node linearly interpolates among a list of
  3D vectors. The keyValue field shall contain exactly as many values
  as in the key field.  4.6.8, Interpolator nodes
  (<http://www.web3d.org/x3d/specifications/vrml/ISO-IEC-14772-VRML97/part1/concepts.html#4.6.8>),
  contains a more detailed discussion of interpolators.

*/

/*!
  \var SoMFVec3f SoVRMLPositionInterpolator::keyValue
  The keyValue vector.
*/

/*!
  \var SoEngineOutput SoVRMLPositionInterpolator::value_changed
  The eventOut which is sent every time the interpolator has calculated a new value.
*/

#include <Inventor/VRMLnodes/SoVRMLPositionInterpolator.h>
#include <Inventor/VRMLnodes/SoVRMLMacros.h>
#include <Inventor/engines/SoSubNodeEngineP.h>

SO_NODEENGINE_SOURCE(SoVRMLPositionInterpolator);

// Doc in parent
void
SoVRMLPositionInterpolator::initClass(void) // static
{
  SO_NODEENGINE_INTERNAL_INIT_CLASS(SoVRMLPositionInterpolator);
}

/*!
  Constructor.
*/
SoVRMLPositionInterpolator::SoVRMLPositionInterpolator(void)
{
  SO_NODEENGINE_INTERNAL_CONSTRUCTOR(SoVRMLPositionInterpolator);

  SO_VRMLNODE_ADD_EMPTY_EXPOSED_MFIELD(keyValue);
  SO_NODEENGINE_ADD_OUTPUT(value_changed, SoSFVec3f);
}

/*!
  Destructor.
*/
SoVRMLPositionInterpolator::~SoVRMLPositionInterpolator()
{
}

// Doc in parent
void
SoVRMLPositionInterpolator::evaluate(void)
{
  float interp;
  int idx = this->getKeyValueIndex(interp);
  if (idx < 0) return;

  const SbVec3f * v = this->keyValue.getValues(0);

  SbVec3f v0 = v[idx];
  if (interp > 0.0f) {
    SbVec3f v1 = v[idx+1];
    v0 = v0 + (v1-v0)*interp;
  }
  SO_ENGINE_OUTPUT(value_changed, SoSFVec3f, setValue(v0));
}

#endif // HAVE_VRML97
