Panda3D

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 "pointerToArray.h"
00021 #include "vector_float.h"
00022 #include "vector_double.h"
00023 #include "vector_LVecBase3f.h"
00024 
00025 class Datagram;
00026 class DatagramIterator;
00027 
00028 ////////////////////////////////////////////////////////////////////
00029 //       Class : FFTCompressor
00030 // Description : This class manages a lossy compression and
00031 //               decompression of a stream of floating-point numbers
00032 //               to a datagram, based a fourier transform algorithm
00033 //               (similar in principle to JPEG compression).
00034 //
00035 //               Actually, it doesn't do any real compression on its
00036 //               own; it just outputs a stream of integers that should
00037 //               compress much tighter via gzip than the original
00038 //               stream of floats would have.
00039 //
00040 //               This class depends on the external FFTW library;
00041 //               without it, it will fall back on lossless output of
00042 //               the original data.
00043 ////////////////////////////////////////////////////////////////////
00044 class EXPCL_PANDA_MATHUTIL FFTCompressor {
00045 public:
00046   FFTCompressor();
00047 
00048   static bool is_compression_available();
00049 
00050   void set_quality(int quality);
00051   int get_quality() const;
00052 
00053   void set_use_error_threshold(bool use_error_threshold);
00054   bool get_use_error_threshold() const;
00055 
00056   void set_transpose_quats(bool flag);
00057   bool get_transpose_quats() const;
00058 
00059   void write_header(Datagram &datagram);
00060   void write_reals(Datagram &datagram, const float *array, int length);
00061   void write_hprs(Datagram &datagram, const LVecBase3f *array, int length);
00062 
00063   bool read_header(DatagramIterator &di, int bam_minor_version);
00064   bool read_reals(DatagramIterator &di, vector_float &array);
00065   bool read_hprs(DatagramIterator &di, vector_LVecBase3f &array,
00066                  bool new_hpr);
00067   bool read_hprs(DatagramIterator &di, vector_LVecBase3f &array);
00068 
00069   static void free_storage();
00070 
00071 private:
00072   enum RunWidth {
00073     // We write a byte to the datagram at the beginning of each run to
00074     // encode the width and length of the run.  The width is indicated
00075     // by the top two bits, while the length fits in the lower six,
00076     // except RW_double, which is a special case.
00077     RW_width_mask  = 0xc0,
00078     RW_length_mask = 0x3f,
00079     RW_0           = 0x00,
00080     RW_8           = 0x40,
00081     RW_16          = 0x80,
00082     RW_32          = 0xc0,
00083     RW_double      = 0xff,
00084     RW_invalid     = 0x01
00085   };
00086 
00087   int write_run(Datagram &datagram, RunWidth run_width,
00088                 const vector_double &run);
00089   int read_run(DatagramIterator &di, vector_double &run);
00090   double get_scale_factor(int i, int length) const;
00091   static double interpolate(double t, double a, double b);
00092 
00093   float get_compressability(const float *data, int length) const;
00094 
00095   int _bam_minor_version;
00096   int _quality;
00097   bool _use_error_threshold;
00098   double _fft_offset;
00099   double _fft_factor;
00100   double _fft_exponent;
00101   bool _transpose_quats;
00102 };
00103 
00104 #endif
00105 
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