Package org.web3d.vrml.export.compressors

Class CompressionTools

java.lang.Object

org.web3d.vrml.export.compressors.CompressionTools

public class CompressionTools
extends Object

A set of general tools for compression routines.

Version:

$Revision: 1.19 $

Author:

Alan Hudson

Constructor Summary

Constructors

Constructor	Description
CompressionTools()

Method Summary

Modifier and Type	Method	Description
static int	calcRange(boolean delta, int span, int[] ival)
static float	calcTolerance(float[] coordinates, float percent)	Calculate a tolerance value as a percentage of the minimum bounds.
static void	compressByteArrayDeltaHuffman(DataOutputStream dos, byte[] data)	Compress a byte array.
static void	compressFloatArray(DataOutputStream dos, boolean delta, int span, float[] fval)	Compress an array of floats.
static void	compressIntArrayDeltaHuffman(DataOutputStream dos, int[] data)	Compress an integer array.
static void	compressShortArrayDeltaHuffman(DataOutputStream dos, short[] data)	Compress a byte array.
static int	computeBits(int value)
static int	convertFloatArrayToIntArray(float[] fval, int[] vals)	Convert an array of floats into an array of integers.
static float[]	decompressFloatArray(InputStream dis, boolean delta, int span)	Decompress a stream into an array of floats.
static int[]	decompressIntArrayDeltaHuffman(InputStream dis)	Decompress an integer array.
static float[]	dequantizeFloatArray(InputStream is)
static float[]	dequantizeFloatArrayHuffman(InputStream is)
static float[]	dequantizeFloatArrayInflater(byte[] data, int start, int length, boolean useLen)
static float[]	dequantizeFloatArrayLZW(InputStream is)
static float[]	dequantizeVector(InputStream is, int exponent, int mantissa, boolean signed, int len)	Dequantize a color vector.
static void	findFloatParams(float[] origvals, float tolerance, int[] output)	Find the float parameters of exponent, mantissa and sign that will express the array of float values within the tolerance specified.
static void	findFloatParams(float origval, float tolerance, int[] output)	Find the float parameters of exponent, mantissa and sign that will express the float value within the tolerance specified.
static void	findFloatParamsOld(float[] origvals, float tolerance, int[] output)	Find the float parameters of exponent, mantissa and sign that will express the array of float values within the tolerance specified.
static void	main(String[] args)
static void	printStats()
static void	quantizeFloatArray(DataOutputStream dos, float[] fval, float tolerance)
static void	quantizeFloatArrayDeflater(DataOutputStream dos, float[] fval, float tolerance, boolean useLen)	Compress a float array by quantizing its values.
static void	quantizeFloatArrayHuffman(DataOutputStream dos, float[] fval, float tolerance)
static void	quantizeFloatArrayLZW(DataOutputStream dos, float[] fval, float tolerance)
static void	quantizeVector(DataOutputStream dos, int exponent, int mantissa, boolean signed, float[] fval)	Quantize a short vector.
static void	rangeCompressIntArray(DataOutputStream dos, boolean delta, int span, int[] ival)	Compress an array of integers by determining the number of bits needed to express the range of values.
static int[]	rangeDecompressIntArray(InputStream dis, boolean delta, int span)	Decompress an array of integers compressed by determining the number of bits needed to express the range of values.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

CompressionTools

public CompressionTools()

Method Details

convertFloatArrayToIntArray

public static int convertFloatArrayToIntArray(float[] fval,
 int[] vals)

Convert an array of floats into an array of integers. A multiplication factor 10^n is returned.

Parameters:

fval - The float data

vals - The integer result. Preallocate this.

Returns:

the multiplier used.

calcTolerance

public static float calcTolerance(float[] coordinates,
 float percent)

Calculate a tolerance value as a percentage of the minimum bounds.

Parameters:

coordinates - The array of coordinates.

percent - The percent of the maximum coordinate range to use as an error.

Returns:

The tolerance value to use.

quantizeFloatArray

public static void quantizeFloatArray(DataOutputStream dos,
 float[] fval,
 float tolerance)
                               throws IOException

Parameters:

dos -

fval -

tolerance -

Throws:

IOException

dequantizeFloatArray

public static float[] dequantizeFloatArray(InputStream is)
                                    throws IOException

Parameters:

is -

Returns:

Throws:

IOException

quantizeVector

public static void quantizeVector(DataOutputStream dos,
 int exponent,
 int mantissa,
 boolean signed,
 float[] fval)
                           throws IOException

Quantize a short vector. The length will not be stored. The (exponent + mantissa + signed) * len must be a multiple of 8.

Parameters:

dos - The output stream

exponent - How many bits to store for the exponent

mantissa - How many bits to store for the mantissa

signed - Is the number sometimes negative

fval - The vector

Throws:

IOException

dequantizeVector

public static float[] dequantizeVector(InputStream is,
 int exponent,
 int mantissa,
 boolean signed,
 int len)
                                throws IOException

Dequantize a color vector. The (exponent + mantissa + sign) * len must be a multiple of 8.

Parameters:

is - The input stream

exponent - How many bits to store for the exponent

mantissa - How many bits to store for the mantissa

signed - Is the number sometimes negative

len - The length of the vector.

Returns:

The decoded vector

Throws:

IOException

compressFloatArray

public static void compressFloatArray(DataOutputStream dos,
 boolean delta,
 int span,
 float[] fval)
                               throws IOException

Compress an array of floats.

Parameters:

dos - The stream to write the results.

delta - Whether to use delta encoding.

span - The repeating frequency of data, a MFVec3f would be a span of 3.

fval - The float array to compress

Throws:

IOException - on an IO error

decompressFloatArray

public static float[] decompressFloatArray(InputStream dis,
 boolean delta,
 int span)
                                    throws IOException

Decompress a stream into an array of floats. This stream must of been encoded via the compressFloatArray call.

Parameters:

dis - The stream to read.

delta - Whether to use delta encoding.

span - The repeating frequency of data, a MFVec3f would be a span of 3.

Returns:

The float array decompressed.

Throws:

IOException - on an IO error

calcRange

public static int calcRange(boolean delta,
 int span,
 int[] ival)

Parameters:

delta -

span -

ival -

Returns:

quantizeFloatArrayHuffman

public static void quantizeFloatArrayHuffman(DataOutputStream dos,
 float[] fval,
 float tolerance)
                                      throws IOException

Parameters:

dos -

fval -

tolerance -

Throws:

IOException

dequantizeFloatArrayHuffman

public static float[] dequantizeFloatArrayHuffman(InputStream is)
                                           throws IOException

Parameters:

is -

Returns:

Throws:

IOException

quantizeFloatArrayLZW

public static void quantizeFloatArrayLZW(DataOutputStream dos,
 float[] fval,
 float tolerance)
                                  throws IOException

Parameters:

dos -

fval -

tolerance -

Throws:

IOException

quantizeFloatArrayDeflater

public static void quantizeFloatArrayDeflater(DataOutputStream dos,
 float[] fval,
 float tolerance,
 boolean useLen)
                                       throws IOException

Compress a float array by quantizing its values.

Parameters:

dos - The output stream

fval - The float values

tolerance - The tolerance allowed between equal values

useLen -

Throws:

IOException

dequantizeFloatArrayInflater

public static float[] dequantizeFloatArrayInflater(byte[] data,
 int start,
 int length,
 boolean useLen)
                                            throws IOException

Parameters:

data -

start - the start position in the array

length - number of values to read from the array

useLen -

Returns:

Throws:

IOException

dequantizeFloatArrayLZW

public static float[] dequantizeFloatArrayLZW(InputStream is)
                                       throws IOException

Parameters:

is -

Returns:

Throws:

IOException

compressIntArrayDeltaHuffman

public static void compressIntArrayDeltaHuffman(DataOutputStream dos,
 int[] data)
                                         throws IOException

Compress an integer array. Uses delta encoding if applicable. Huffman encodes the result.

Parameters:

dos - The stream to write to

data - The integer array to encode.

Throws:

IOException

decompressIntArrayDeltaHuffman

public static int[] decompressIntArrayDeltaHuffman(InputStream dis)
                                            throws IOException

Decompress an integer array. Uses delta encoding if applicable. Huffman encodes the result.

Parameters:

dis - The stream to write to

Returns:

The integer array with the decompressed info

Throws:

IOException

compressByteArrayDeltaHuffman

public static void compressByteArrayDeltaHuffman(DataOutputStream dos,
 byte[] data)
                                          throws IOException

Compress a byte array. Uses delta encoding if applicable. Huffman encodes the result.

Parameters:

dos - The stream to write to

data - The integer array to encode.

Throws:

IOException

compressShortArrayDeltaHuffman

public static void compressShortArrayDeltaHuffman(DataOutputStream dos,
 short[] data)
                                           throws IOException

Compress a byte array. Uses delta encoding if applicable. Huffman encodes the result.

Parameters:

dos - The stream to write to

data - The integer array to encode.

Throws:

IOException

rangeCompressIntArray

public static void rangeCompressIntArray(DataOutputStream dos,
 boolean delta,
 int span,
 int[] ival)
                                  throws IOException

Compress an array of integers by determining the number of bits needed to express the range of values. Optional delta coding is provided. Format: Number of ints encoded(27, nothing else if length=0) Number if bits per entry(5) Shift(32) Initial value(32 * span,if delta encoding)

Parameters:

dos -

delta -

span -

ival -

Throws:

IOException

rangeDecompressIntArray

public static int[] rangeDecompressIntArray(InputStream dis,
 boolean delta,
 int span)
                                     throws IOException

Decompress an array of integers compressed by determining the number of bits needed to express the range of values. Optional delta coding is provided. Format: Number of ints encoded(27) Number if bits per entry(5, nothing else if length=0) Shift(32) Initial value(32 * span,if delta encoding)

Parameters:

dis -

delta -

span -

Returns:

Throws:

IOException

computeBits

public static int computeBits(int value)

Parameters:

value -

Returns:

printStats

public static void printStats()

findFloatParams

public static void findFloatParams(float origval,
 float tolerance,
 int[] output)

Find the float parameters of exponent, mantissa and sign that will express the float value within the tolerance specified.

Parameters:

origval - The original value

tolerance - The error tolerance

output - The exponent, mantissa and sign bits needed

findFloatParams

public static void findFloatParams(float[] origvals,
 float tolerance,
 int[] output)

Find the float parameters of exponent, mantissa and sign that will express the array of float values within the tolerance specified.

Parameters:

origvals - The original value

tolerance - The error tolerance

output - The exponent, mantissa and sign bits needed

findFloatParamsOld

public static void findFloatParamsOld(float[] origvals,
 float tolerance,
 int[] output)

Find the float parameters of exponent, mantissa and sign that will express the array of float values within the tolerance specified.

Parameters:

origvals - The original value

tolerance - The error tolerance

output - The exponent, mantissa and sign bits needed

main

public static void main(String[] args)

Parameters:

args -