Panda3D
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fftCompressor.h
00001 // Filename: fftCompressor.h
00002 // Created by:  drose (11Dec00)
00003 //
00004 ////////////////////////////////////////////////////////////////////
00005 //
00006 // PANDA 3D SOFTWARE
00007 // Copyright (c) Carnegie Mellon University.  All rights reserved.
00008 //
00009 // All use of this software is subject to the terms of the revised BSD
00010 // license.  You should have received a copy of this license along
00011 // with this source code in a file named "LICENSE."
00012 //
00013 ////////////////////////////////////////////////////////////////////
00014 
00015 #ifndef FFTCOMPRESSOR_H
00016 #define FFTCOMPRESSOR_H
00017 
00018 #include "pandabase.h"
00019 
00020 #include "pvector.h"
00021 #include "pointerToArray.h"
00022 #include "vector_stdfloat.h"
00023 #include "vector_double.h"
00024 #include "luse.h"
00025 
00026 class Datagram;
00027 class DatagramIterator;
00028 
00029 ////////////////////////////////////////////////////////////////////
00030 //       Class : FFTCompressor
00031 // Description : This class manages a lossy compression and
00032 //               decompression of a stream of floating-point numbers
00033 //               to a datagram, based a fourier transform algorithm
00034 //               (similar in principle to JPEG compression).
00035 //
00036 //               Actually, it doesn't do any real compression on its
00037 //               own; it just outputs a stream of integers that should
00038 //               compress much tighter via gzip than the original
00039 //               stream of floats would have.
00040 //
00041 //               This class depends on the external FFTW library;
00042 //               without it, it will fall back on lossless output of
00043 //               the original data.
00044 ////////////////////////////////////////////////////////////////////
00045 class EXPCL_PANDA_MATHUTIL FFTCompressor {
00046 public:
00047   FFTCompressor();
00048 
00049   static bool is_compression_available();
00050 
00051   void set_quality(int quality);
00052   int get_quality() const;
00053 
00054   void set_use_error_threshold(bool use_error_threshold);
00055   bool get_use_error_threshold() const;
00056 
00057   void set_transpose_quats(bool flag);
00058   bool get_transpose_quats() const;
00059 
00060   void write_header(Datagram &datagram);
00061   void write_reals(Datagram &datagram, const PN_stdfloat *array, int length);
00062   void write_hprs(Datagram &datagram, const LVecBase3 *array, int length);
00063 
00064   bool read_header(DatagramIterator &di, int bam_minor_version);
00065   bool read_reals(DatagramIterator &di, vector_stdfloat &array);
00066   bool read_hprs(DatagramIterator &di, pvector<LVecBase3> &array,
00067                  bool new_hpr);
00068   bool read_hprs(DatagramIterator &di, pvector<LVecBase3> &array);
00069 
00070   static void free_storage();
00071 
00072 private:
00073   enum RunWidth {
00074     // We write a byte to the datagram at the beginning of each run to
00075     // encode the width and length of the run.  The width is indicated
00076     // by the top two bits, while the length fits in the lower six,
00077     // except RW_double, which is a special case.
00078     RW_width_mask  = 0xc0,
00079     RW_length_mask = 0x3f,
00080     RW_0           = 0x00,
00081     RW_8           = 0x40,
00082     RW_16          = 0x80,
00083     RW_32          = 0xc0,
00084     RW_double      = 0xff,
00085     RW_invalid     = 0x01
00086   };
00087 
00088   int write_run(Datagram &datagram, RunWidth run_width,
00089                 const vector_double &run);
00090   int read_run(DatagramIterator &di, vector_double &run);
00091   double get_scale_factor(int i, int length) const;
00092   static double interpolate(double t, double a, double b);
00093 
00094   PN_stdfloat get_compressability(const PN_stdfloat *data, int length) const;
00095 
00096   int _bam_minor_version;
00097   int _quality;
00098   bool _use_error_threshold;
00099   double _fft_offset;
00100   double _fft_factor;
00101   double _fft_exponent;
00102   bool _transpose_quats;
00103 };
00104 
00105 #endif
00106 
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