vmmlib  1.12.0
Templatized C++ vector and matrix math library
lowpassFilter.hpp
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32 
33 /* @author Jafet Villafranca
34  *
35  * Implements low pass filtering on a templated data type, which needs to
36  * implement multiplication by a scalar float for smoothing
37  */
38 
39 #ifndef __VMML__LOWPASS_FILTER__HPP__
40 #define __VMML__LOWPASS_FILTER__HPP__
41 
42 #include <deque>
43 
44 namespace vmml
45 {
46 template< size_t M, typename T > class LowpassFilter
47 {
48 public:
50  LowpassFilter( const float F ) : _smoothFactor( F ) {}
51  ~LowpassFilter() {}
52 
54  const T& get() const { return _value; }
55 
57  const T* operator->() const { return &_value; }
58 
60  const T& operator*() const { return _value; }
61 
63  const T& add( const T& value );
64 
65 private:
66  std::deque< T > _data;
67  float _smoothFactor;
68  T _value;
69 };
70 
71 
72 template< size_t M, typename T >
73 const T& LowpassFilter< M, T >::add( const T& value )
74 {
75  _data.push_front( value );
76 
77  while( _data.size() > M )
78  _data.pop_back();
79 
80  // update
81  typename std::deque< T >::const_iterator i = _data.begin();
82  _value = *i;
83  double weight = _smoothFactor;
84 
85  for( ++i ; i != _data.end(); ++i )
86  {
87  _value = _value * (1 - weight) + (*i) * weight;
88  weight *= _smoothFactor;
89  }
90 
91  return _value;
92 }
93 
94 } // namespace vmml
95 
96 #endif
LowpassFilter(const float F)
Construct a new lowpass filter with the given smoothing.
const T * operator->() const
Access the filtered value.
heavily inspired by boost::enable_if http://www.boost.org, file: boost/utility/enable_if.hpp, Copyright 2003 Jaakko Järvi, Jeremiah Willcock, Andrew Lumsdaine
Definition: aabb.hpp:40
const T & operator*() const
Access the filtered value.
const T & add(const T &value)
Add a value to the data set and return the filtered output.