This class manages a lossy compression and decompression of a stream of floating-point numbers to a datagram, based a fourier transform algorithm (similar in principle to JPEG compression). More...
#include "fftCompressor.h"
Public Member Functions | |
| FFTCompressor () | |
| Constructs a new compressor object with default parameters. More... | |
| int | get_quality () const |
| Returns the quality number that was previously set via set_quality(). More... | |
| bool | get_transpose_quats () const |
| Returns the transpose_quats flag. More... | |
| bool | get_use_error_threshold () const |
| Returns whether the error threshold measurement is enabled. More... | |
| bool | read_header (DatagramIterator &di, int bam_minor_version) |
| Reads the compression header that was written previously. More... | |
| bool | read_hprs (DatagramIterator &di, pvector< LVecBase3 > &array, bool new_hpr) |
| Reads an array of HPR angles. More... | |
| bool | read_hprs (DatagramIterator &di, pvector< LVecBase3 > &array) |
| Reads an array of HPR angles. More... | |
| bool | read_reals (DatagramIterator &di, vector_stdfloat &array) |
| Reads an array of floating-point numbers. More... | |
| void | set_quality (int quality) |
| Sets the quality factor for the compression. More... | |
| void | set_transpose_quats (bool flag) |
| Sets the transpose_quats flag. More... | |
| void | set_use_error_threshold (bool use_error_threshold) |
| Enables or disables the use of the error threshold measurement to put a cap on the amount of damage done by lossy compression. More... | |
| void | write_header (Datagram &datagram) |
| Writes the compression parameters to the indicated datagram. More... | |
| void | write_hprs (Datagram &datagram, const LVecBase3 *array, int length) |
| Writes an array of HPR angles to the indicated datagram. More... | |
| void | write_reals (Datagram &datagram, const PN_stdfloat *array, int length) |
| Writes an array of floating-point numbers to the indicated datagram. More... | |
Static Public Member Functions | |
| static void | free_storage () |
| Frees memory that has been allocated during past runs of the FFTCompressor. More... | |
| static bool | is_compression_available () |
| Returns true if the FFTW library is compiled in, so that this class is actually capable of doing useful compression/decompression work. More... | |
This class manages a lossy compression and decompression of a stream of floating-point numbers to a datagram, based a fourier transform algorithm (similar in principle to JPEG compression).
Actually, it doesn't do any real compression on its own; it just outputs a stream of integers that should compress much tighter via gzip than the original stream of floats would have.
This class depends on the external FFTW library; without it, it will fall back on lossless output of the original data.
Definition at line 40 of file fftCompressor.h.
| FFTCompressor::FFTCompressor | ( | ) |
Constructs a new compressor object with default parameters.
Definition at line 49 of file fftCompressor.cxx.
References set_quality().
|
static |
Frees memory that has been allocated during past runs of the FFTCompressor.
This is an optional call, but it may be made from time to time to empty the global cache that the compressor objects keep to facilitate fast compression/decompression.
Definition at line 820 of file fftCompressor.cxx.
| int FFTCompressor::get_quality | ( | ) | const |
Returns the quality number that was previously set via set_quality().
Definition at line 139 of file fftCompressor.cxx.
| bool FFTCompressor::get_transpose_quats | ( | ) | const |
Returns the transpose_quats flag.
Definition at line 179 of file fftCompressor.cxx.
| bool FFTCompressor::get_use_error_threshold | ( | ) | const |
Returns whether the error threshold measurement is enabled.
See set_use_error_threshold().
Definition at line 161 of file fftCompressor.cxx.
|
static |
Returns true if the FFTW library is compiled in, so that this class is actually capable of doing useful compression/decompression work.
Returns false otherwise, in which case any attempt to write a compressed stream will actually write an uncompressed stream, and any attempt to read a compressed stream will fail.
Definition at line 64 of file fftCompressor.cxx.
Referenced by EggJointData::score_reparent_to().
| bool FFTCompressor::read_header | ( | DatagramIterator & | di, |
| int | bam_minor_version | ||
| ) |
Reads the compression header that was written previously.
This fills in the compression parameters necessary to correctly decompress the following data.
Returns true if the header is read successfully, false otherwise.
Definition at line 541 of file fftCompressor.cxx.
References DatagramIterator::get_float64(), DatagramIterator::get_int8(), and set_quality().
| bool FFTCompressor::read_hprs | ( | DatagramIterator & | di, |
| pvector< LVecBase3 > & | array, | ||
| bool | new_hpr | ||
| ) |
Reads an array of HPR angles.
The result is pushed onto the end of the indicated vector, which is not cleared first; it is the user's responsibility to ensure that the array is initially empty.
new_hpr is a temporary, transitional parameter. If it is set false, the hprs are decompressed according to the old, broken hpr calculation; if true, the hprs are decompressed according to the new, correct hpr calculation.
Definition at line 681 of file fftCompressor.cxx.
Referenced by read_hprs().
| bool FFTCompressor::read_hprs | ( | DatagramIterator & | di, |
| pvector< LVecBase3 > & | array | ||
| ) |
Reads an array of HPR angles.
The result is pushed onto the end of the indicated vector, which is not cleared first; it is the user's responsibility to ensure that the array is initially empty.
Definition at line 808 of file fftCompressor.cxx.
References read_hprs().
| bool FFTCompressor::read_reals | ( | DatagramIterator & | di, |
| vector_stdfloat & | array | ||
| ) |
Reads an array of floating-point numbers.
The result is pushed onto the end of the indicated vector, which is not cleared first; it is the user's responsibility to ensure that the array is initially empty. Returns true if the data is read correctly, false if there is an error.
Definition at line 576 of file fftCompressor.cxx.
References DatagramIterator::get_int32().
| void FFTCompressor::set_quality | ( | int | quality | ) |
Sets the quality factor for the compression.
This is an integer in the range 0 - 100 that roughly controls how aggressively the reals are compressed; lower numbers mean smaller output, and more data loss.
There are a few special cases. Quality -1 means to use whatever individual parameters are set in the user's Configrc file, rather than the single quality dial. Quality 101 or higher means to generate lossless output (this is the default if libfftw is not available).
Quality 102 writes all four components of quaternions to the output file, rather than just three, quality 103 converts hpr to matrix (instead of quat) and writes a 9-component matrix, and quality 104 just writes out hpr directly. Quality levels 102 and greater are strictly for debugging purposes, and are only available if NDEBUG is not defined.
Definition at line 89 of file fftCompressor.cxx.
Referenced by FFTCompressor(), and read_header().
| void FFTCompressor::set_transpose_quats | ( | bool | flag | ) |
Sets the transpose_quats flag.
This is provided mainly for backward compatibility with old bam files that were written out with the quaternions inadvertently transposed.
Definition at line 171 of file fftCompressor.cxx.
| void FFTCompressor::set_use_error_threshold | ( | bool | use_error_threshold | ) |
Enables or disables the use of the error threshold measurement to put a cap on the amount of damage done by lossy compression.
When this is enabled, the potential results of the compression are analyzed before the data is written; if it is determined that the compression will damage a particular string of reals too much, that particular string of reals is written uncompressed.
Definition at line 152 of file fftCompressor.cxx.
| void FFTCompressor::write_header | ( | Datagram & | datagram | ) |
Writes the compression parameters to the indicated datagram.
It is necessary to call this before writing anything else to the datagram, since these parameters will be necessary to correctly decompress the data later.
Definition at line 189 of file fftCompressor.cxx.
References Datagram::add_float64(), and Datagram::add_int8().
| void FFTCompressor::write_hprs | ( | Datagram & | datagram, |
| const LVecBase3 * | array, | ||
| int | length | ||
| ) |
Writes an array of HPR angles to the indicated datagram.
Definition at line 371 of file fftCompressor.cxx.
| void FFTCompressor::write_reals | ( | Datagram & | datagram, |
| const PN_stdfloat * | array, | ||
| int | length | ||
| ) |
Writes an array of floating-point numbers to the indicated datagram.
Definition at line 202 of file fftCompressor.cxx.
References Datagram::add_int32().
1.8.15