compressedgeometryfile.java

JAVA3D矩陈的相关类

/*
 * $RCSfile: CompressedGeometryFile.java,v $
 *
 * Copyright (c) 2007 Sun Microsystems, Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistribution of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistribution in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in
 *   the documentation and/or other materials provided with the
 *   distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of
 * contributors may be used to endorse or promote products derived
 * from this software without specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any
 * kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND
 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY
 * EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL
 * NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF
 * USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR
 * ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL,
 * CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND
 * REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF OR
 * INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 *
 * You acknowledge that this software is not designed, licensed or
 * intended for use in the design, construction, operation or
 * maintenance of any nuclear facility.
 *
 * $Revision: 1.3 $
 * $Date: 2007/02/09 17:20:21 $
 * $State: Exp $
 */

package com.sun.j3d.utils.geometry.compression;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;

//
// The compressed geometry file format supported by this class has a 32
// byte header followed by multiple compressed geometry objects.
//
// Each object consists of a block of compressed data and an 8-byte
// individual block header describing its contents.
//
// The file ends with a directory data structure used for random access,
// containing a 64-bit offset for each object in the order in which it
// appears in the file.  This is also used to find the size of the largest
// object in the file and must be present.
//

/**
 * This class provides methods to read and write compressed geometry resource
 * files.  These files usually end with the .cg extension and support
 * sequential as well as random access to multiple compressed geometry
 * objects.
 *
 * @since Java 3D 1.5
 */
public class CompressedGeometryFile {
    private static final boolean print = false ;
    private static final boolean benchmark = false ;

    /**
     * The magic number which identifies the compressed geometry file type.
     */
    static final int MAGIC_NUMBER = 0xbaddfab4 ;

    /**
     * Byte offset of the magic number from start of file.
     */
    static final int MAGIC_NUMBER_OFFSET = 0 ;

    /**
     * Byte offset of the major version number from start of file.
     */
    static final int MAJOR_VERSION_OFFSET = 4 ;

    /**
     * Byte offset of the minor version number from start of file.
     */
    static final int MINOR_VERSION_OFFSET = 8 ;

    /**
     * Byte offset of the minor minor version number from start of file.
     */
    static final int MINOR_MINOR_VERSION_OFFSET = 12 ;

    /**
     * Byte offset of the number of objects from start of file.
     */
    static final int OBJECT_COUNT_OFFSET  = 16 ;

    /**
     * Byte offset of the directory offset from start of file.
     * This offset is long word aligned since the directory offset is a long.
     */
    static final int DIRECTORY_OFFSET_OFFSET = 24 ;

    /**
     * File header total size in bytes.
     */
    static final int HEADER_SIZE = 32 ;

    /**
     * Byte offset of the object size from start of individual compressed
     * geometry block.
     */
    static final int OBJECT_SIZE_OFFSET = 0 ;

    /**
     * Byte offset of the compressed geometry data descriptor from start of
     * individual compressed geometry block.
     */
    static final int GEOM_DATA_OFFSET = 4 ;

    /**
     * Bits in compressed geometry data descriptor which encode the buffer type.
     */
    static final int TYPE_MASK = 0x03 ;

    /**
     * Bit in compressed geometry data descriptor encoding presence of normals.
     */
    static final int NORMAL_PRESENT_MASK = 0x04 ;

    /**
     * Bit in compressed geometry data descriptor encoding presence of colors.
     */
    static final int COLOR_PRESENT_MASK = 0x08 ;

    /**
     * Bit in compressed geometry data descriptor encoding presence of alphas.
     */
    static final int ALPHA_PRESENT_MASK = 0x10 ;

    /**
     * Value in compressed geometry data descriptor for a point buffer type.
     */
    static final int TYPE_POINT = 1 ;

    /**
     * Value in compressed geometry data descriptor for a line buffer type.
     */
    static final int TYPE_LINE = 2 ;

    /**
     * Value in compressed geometry data descriptor for a triangle buffer type.
     */
    static final int TYPE_TRIANGLE = 3 ;

    /**
     * Block header total size in bytes.
     */
    static final int BLOCK_HEADER_SIZE = 8 ;

    // The name of the compressed geometry resource file.
    String fileName = null ;

    // The major, minor, and subminor version number of the most recent
    // compressor used to compress any of the objects in the compressed
    // geometry resource file.
    int majorVersionNumber ;
    int minorVersionNumber ;
    int minorMinorVersionNumber ;

    // The number of objects in the compressed geometry resource file.
    int objectCount ;

    // The index of the current object in the file.
    int objectIndex = 0 ;

    // The random access file associated with this instance.
    RandomAccessFile cgFile = null ;

    // The magic number identifying the file type.
    int magicNumber ;

    // These fields are set from each individual block of compressed geometry.
    byte cgBuffer[] ;
    int geomSize ;
    int geomStart ;
    int geomDataType ;

    // The directory of object offsets is read from the end of the file.
    long directory[] ;
    long directoryOffset ;

    // The object sizes are computed from the directory offsets.  These are
    // used to allocate a buffer large enough to hold the largest object and
    // to determine how many consecutive objects can be read into that buffer.
    int objectSizes[] ;
    int bufferObjectStart ;
    int bufferObjectCount ;
    int bufferNextObjectCount ;
    int bufferNextObjectOffset ;

    // The shared compressed geometry header object.
    CompressedGeometryData.Header cgh ;

    // Flag indicating file update.
    boolean fileUpdate = false ;

    /**
     * Construct a new CompressedGeometryFile instance associated with the
     * specified file.  An attempt is made to open the file with read-only
     * access; if this fails then a FileNotFoundException is thrown.
     *
     * @param file path to the compressed geometry resource file
     * @exception FileNotFoundException if file doesn't exist or
     * cannot be read
     * @exception IllegalArgumentException if the file is not a compressed
     * geometry resource file
     * @exception IOException if there is a header or directory read error
     */
    public CompressedGeometryFile(String file) throws IOException {
	this(file, false) ;
    }

    /**
     * Construct a new CompressedGeometryFile instance associated with the
     * specified file.
     *
     * @param file path to the compressed geometry resource file
     * @param rw if true, opens the file for read and write access or attempts
     * to create one if it doesn't exist; if false, opens the file with
     * read-only access
     * @exception FileNotFoundException if file doesn't exist or
     * access permissions disallow access
     * @exception IllegalArgumentException if the file is not a compressed
     * geometry resource file
     * @exception IOException if there is a header or directory read error
     */
    public CompressedGeometryFile(String file, boolean rw) throws IOException {
	// Open the file and read the file header.
	open(file, rw) ;

	// Copy the file name.
	fileName = new String(file) ;

	// Set up the file fields.
	initialize() ;
    }

    /**
     * Construct a new CompressedGeometryFile instance associated with a
     * currently open RandomAccessFile.
     *
     * @param file currently open RandomAccessFile
     * @exception IllegalArgumentException if the file is not a compressed
     * geometry resource file
     * @exception IOException if there is a header or directory read error
     */
    public CompressedGeometryFile(RandomAccessFile file) throws IOException {
	// Copy the file reference.
	cgFile = file ;
	
	// Set up the file fields.
	initialize() ;
    }

    /**
     * Delete all compressed objects from this instance.  This method may only
     * be called after successfully creating a CompressedGeometryFile instance
     * with read-write access, so a corrupted or otherwise invalid resource
     * must be removed manually before it can be rewritten.  The close()
     * method must be called sometime after invoking clear() in order to write
     * out the new directory structure.
     * 
     * @exception IOException if clear fails
     */
    public void clear() throws IOException {
	// Truncate the file.
	cgFile.setLength(0) ;

	// Set up the file fields.
	initialize() ;
    }

    /**
     * Return a string containing the file name associated with this instance
     * or null if there is none.
     *
     * @return file name associated with this instance or null if there is
     * none
     */
    public String getFileName() {
	return fileName ;
    }

    /**
     * Return the major version number of the most recent compressor used to
     * compress any of the objects in this instance.
     *
     * @return major version number
     */
    public int getMajorVersionNumber() {
	return majorVersionNumber ;
    }

    /**
     * Return the minor version number of the most recent compressor used to
     * compress any of the objects in this instance.
     *
     * @return minor version number
     */
    public int getMinorVersionNumber() {
	return minorVersionNumber ;
    }

    /**
     * Return the subminor version number of the most recent compressor used to
     * compress any of the objects in this instance.
     *
     * @return subminor version number
     */
    public int getMinorMinorVersionNumber() {
	return minorMinorVersionNumber ;
    }

    /**
     * Return the number of compressed objects in this instance.
     *
     * @return number of compressed objects
     */
    public int getObjectCount() {