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  #ifdef HAVE_CONFIG_H
  #include <config.h>
  #endif // HAVE_CONFIG_H
  
  #ifdef HAVE_VRML97
  
  /*!
    \class SoVRMLScalarInterpolator SoVRMLScalarInterpolator.h Inventor/VRMLnodes/SoVRMLScalarInterpolator.h
    \brief The SoVRMLScalarInterpolator class is used to interpolate scalar values.
  
    \ingroup VRMLnodes
    
    \verbatim
    ScalarInterpolator {
      eventIn      SFFloat set_fraction         # (-inf, inf)
      exposedField MFFloat key           []     # (-inf, inf)
      exposedField MFFloat keyValue      []     # (-inf, inf)
      eventOut     SFFloat value_changed
    }
    \endverbatim
  
    This node linearly interpolates among a list of SFFloat values. This
    interpolator is appropriate for any parameter defined using a single
    floating point value. Examples include width, radius, and intensity
    fields. The keyValue field shall contain exactly as many numbers as
    there are keyframes in the key field.  A more detailed discussion of
    interpolators is available in 4.6.8, Interpolator nodes
    (<http://www.web3d.org/documents/specifications/14772/V2.0/part1/concepts.html#4.6.8>).
     
  */
  
  /*!
    \var SoMFFloat SoVRMLScalarInterpolator::keyValue
    The keyValue vector.
  */
  
  /*!
    \var SoEngineOutput SoVRMLScalarInterpolator::value_changed
    The eventOut which is sent every time the interpolator has calculated a new value.
  */
  
  #include <Inventor/VRMLnodes/SoVRMLScalarInterpolator.h>
  
  #include <Inventor/VRMLnodes/SoVRMLMacros.h>
  
  #include "engines/SoSubNodeEngineP.h"
  
  SO_NODEENGINE_SOURCE(SoVRMLScalarInterpolator);
  
  // Doc in parent
  void
  SoVRMLScalarInterpolator::initClass(void) // static
  {
    SO_NODEENGINE_INTERNAL_INIT_CLASS(SoVRMLScalarInterpolator);
  }
  
  /*!
    Constructor.
  */
  SoVRMLScalarInterpolator::SoVRMLScalarInterpolator(void)
  {
    SO_NODEENGINE_INTERNAL_CONSTRUCTOR(SoVRMLScalarInterpolator);
  
    SO_VRMLNODE_ADD_EMPTY_EXPOSED_MFIELD(keyValue);
    SO_NODEENGINE_ADD_OUTPUT(value_changed, SoSFFloat);
  }
  
  /*!
    Destructor.
  */
  SoVRMLScalarInterpolator::~SoVRMLScalarInterpolator()
  {
  }
  
  // Doc in parent
  void
  SoVRMLScalarInterpolator::evaluate(void)
  {
    float interp;
    int idx = this->getKeyValueIndex(interp, this->keyValue.getNum());
    if (idx < 0) return;
  
    const float * v = this->keyValue.getValues(0);
  
    float v0 = v[idx];
    if (interp > 0.0f) {
      float v1 = v[idx+1];
      v0 = v0 + (v1-v0)*interp;
    }
    SO_ENGINE_OUTPUT(value_changed, SoSFFloat, setValue(v0));
  }
  
  #endif // HAVE_VRML97
  