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include/cinder/Filter.h

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00001 /*
00002  Copyright (c) 2010, The Barbarian Group
00003  All rights reserved.
00004 
00005  Redistribution and use in source and binary forms, with or without modification, are permitted provided that
00006  the following conditions are met:
00007 
00008     * Redistributions of source code must retain the above copyright notice, this list of conditions and
00009     the following disclaimer.
00010     * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and
00011     the following disclaimer in the documentation and/or other materials provided with the distribution.
00012 
00013  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
00014  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
00015  PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
00016  ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
00017  TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
00018  HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
00019  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
00020  POSSIBILITY OF SUCH DAMAGE.
00021 */
00022 
00023 #pragma once
00024 
00025 #include "cinder/CinderMath.h"
00026 
00027 namespace cinder {
00028 
00029 class FilterBase {
00030  public:
00031     FilterBase( float aSupport ) : mSupport( aSupport ) {}
00032     virtual ~FilterBase() {};
00033     
00034     float           getSupport() const { return mSupport; }
00035     void            setSupport( float aSupport ) { mSupport = aSupport; }
00036     
00037     virtual float   operator()( float x ) const = 0;
00038  protected:
00039     float           mSupport;
00040 };
00041 
00042 // box, pulse, nearest-neighbor, Fourier window, 1st order (constant) b-spline 
00043 class FilterBox : public FilterBase {
00044  public:
00045     FilterBox( float aSupport = 0.5f ) : FilterBase( aSupport ) {}
00046     
00047     virtual float operator()( float x ) const {
00048         if ( x < -0.5f ) return 0.0f;
00049         else if ( x < 0.5f ) return 1.0f;
00050         return 0.0f;
00051     }
00052 };
00053 
00054 // triangle, Bartlett window, 2nd order (linear) b-spline
00055 class FilterTriangle : public FilterBase {
00056  public:
00057     FilterTriangle( float aSupport = 1.0f ) : FilterBase( aSupport ) {}
00058     
00059     virtual float operator()( float x ) const {
00060         if ( x < -1.0f ) return 0.0f;
00061         else if ( x < 0.0f ) return 1.0f + x;
00062         else if ( x < 1.0f ) return 1.0f - x;
00063         return 0.0f;
00064     }
00065 };
00066 
00067 // 3rd order (quadratic) b-spline
00068 class FilterQuadratic : public FilterBase {
00069  public:
00070     FilterQuadratic( float aSupport = 1.5f ) : FilterBase( aSupport ) {}
00071     
00072     virtual float operator()( float x ) const {
00073         float t;
00074 
00075         if ( x < -1.5f ) return 0.0f;
00076         else if ( x < -0.5f ) { t = x + 1.5f; return 0.5f * t * t; }
00077         else if ( x < 0.5f ) return 0.75f - x * x;
00078         else if ( x < 1.5f ) { t = x - 1.5f; return 0.5f * t * t; }
00079         return 0.0f;
00080     }
00081 };
00082 
00083 // 4th order (cubic) b-spline
00084 class FilterCubic : public FilterBase {
00085  public:
00086     FilterCubic( float aSupport = 2.0f ) : FilterBase( aSupport ) {}
00087     
00088     virtual float operator()( float x ) const {
00089         float t;
00090 
00091         if ( x < -2.0f ) return 0.0f;
00092         else if ( x < -1.0f ) { t = 2.0f + x; return t * t * t / 6.0f; }
00093         else if ( x < 0.0f ) return ( 4.0f + x * x * ( -6.0f + x * -3.0f ) ) / 6.0f;
00094         else if ( x < 1.0f ) return ( 4.0f + x * x * ( -6.0f + x * 3.0f ) ) / 6.0f;
00095         else if ( x < 2.0f ) { t = 2.0f - x; return t * t * t / 6.0f; }
00096         return 0.0f;
00097     }
00098 };
00099 
00100 // Catmull-Rom spline, Overhauser spline
00101 class FilterCatmullRom : public FilterBase {
00102  public:
00103     FilterCatmullRom( float aSupport = 2.0f ) : FilterBase( aSupport ) {}
00104     
00105     virtual float operator()( float x ) const {
00106         if ( x < -2.0f ) return 0.0f;
00107         else if ( x < -1.0f ) return 0.5f * ( 4.0f + x * ( 8.0f + x * ( 5.0f + x ) ) );
00108         else if ( x < 0.0f ) return 0.5f * ( 2.0f + x * x * ( -5.0f + x * -3.0f ) );
00109         else if ( x < 1.0f ) return 0.5f * ( 2.0f + x * x * ( -5.0f + x * 3.0f ) );
00110         else if ( x < 2.0f ) return 0.5f * ( 4.0f + x * ( -8.0f + x * ( 5.0f - x ) ) );
00111         return 0.0f;
00112     }
00113 };
00114 
00115 // Mitchell & Netravali's two-parameter cubic
00116 // see Mitchell&Netravali, "Reconstruction Filters in Computer Graphics", SIGGRAPH 88
00117 class FilterMitchell : public FilterBase {
00118  public:
00119     FilterMitchell( float aSupport = 2.0f, float b = 0.3333333333f, float c = 0.3333333333f ) : FilterBase( aSupport ) {
00120         mP0 = ( 6.0f - 2.0f * b ) / 6.0f;
00121         mP2 = ( -18.0f + 12.0f * b + 6.0f * c ) / 6.0f;
00122         mP3 = ( 12.0f - 9.0f * b - 6.0f * c ) / 6.0f;
00123         mQ0 = ( 8.0f * b + 24.0f * c ) / 6.0f;
00124         mQ1 = ( - 12.0f * b - 48.0f * c ) / 6.0f;
00125         mQ2 = ( 6.0f * b + 30.0f * c ) / 6.0f;
00126         mQ3 = ( -b - 6.0f * c ) / 6.0f;
00127     }
00128     
00129     virtual float operator()( float x ) const {
00130         if ( x < -2.0f ) return 0.;
00131         else if ( x < -1.0f ) return mQ0 - x * ( mQ1 - x * ( mQ2 - x * mQ3 ) );
00132         else if ( x < 0.0f ) return mP0 + x * x * ( mP2 - x * mP3 );
00133         else if ( x < 1.0f ) return mP0 + x * x * ( mP2 + x * mP3 );
00134         else if ( x < 2.0f ) return mQ0 + x * ( mQ1 + x * ( mQ2 + x * mQ3 ) );
00135         return 0.0f;
00136     }
00137     
00138  private:
00139     float mQ0, mQ1, mQ2, mQ3;
00140     float mP0, mP2, mP3;
00141 };
00142 
00143 // sinc filter, windowed by blackman
00144 class FilterSincBlackman : public FilterBase {
00145  public:
00146     FilterSincBlackman( float aSupport = 4.0f ) : FilterBase( aSupport ) {}
00147     
00148     virtual float operator()( float x ) const {
00149         float v( ( x == 0.0f ) ? 1.0f : math<float>::sin( 3.14159265358979323846f * x ) / ( 3.14159265358979323846f * x ) );
00150         // blackman
00151         x /= mSupport;
00152         return v * ( 0.42f + 0.50f * math<float>::cos( 3.14159265358979323846f * x ) + 0.08f * math<float>::cos( 6.2831853071795862f * x ) );
00153     }
00154 };
00155 
00156 // sinc filter, windowed by blackman
00157 class FilterGaussian : public FilterBase {
00158  public:
00159     FilterGaussian( float aSupport = 1.25f ) : FilterBase( aSupport ) {}
00160     
00161     virtual float operator()( float x ) const {
00162         return ( math<float>::exp( -2.0f * x * x ) * math<float>::sqrt( 2.0f / 3.14159265358979323846f ) );
00163     }
00164 };
00165 
00166 #if ! defined( CINDER_COCOA_TOUCH )
00167 class FilterBesselBlackman : public FilterBase {
00168  public:
00169     FilterBesselBlackman( float aSupport = 3.2383f ) : FilterBase( aSupport ) {}
00170     
00171     virtual float operator()( float x ) const {
00172 #if defined (CINDER_MSW)
00173         // According to VS.Net 2K5, j1 was depcreated, use _j1 instead. 
00174         float v( ( x == 0.0f ) ? ( 3.14159265358979323846f / 4.0f ) : static_cast<float>( _j1( 3.14159265358979323846f * x ) ) / ( 2.0f * x ) );
00175 #else 
00176         float v( ( x == 0.0f ) ? ( 3.14159265358979323846f / 4.0f ) : static_cast<float>( j1( 3.14159265358979323846f * x ) ) / ( 2.0f * x ) );
00177 #endif 
00178         // always bet on blackman
00179         x /= mSupport;
00180         return v * ( 0.42f + 0.50f * math<float>::cos( 3.14159265358979323846f * x ) + 0.08f * math<float>::cos( 6.2831853071795862f * x ) );       
00181     }
00182 };
00183 #endif
00184 
00185 } // namespace cinder