Boundary Format
From World Wind Wiki
This has been translated from the original page in French.
Note: The usefulness or effectiveness of the altitude in pkg files with World Wind 1.3 is up in the air. See this thread for details
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Introduction
The wwb files are used to define boundaries (countries and states), and you can make a pathlist with them using PathListArchiver.exe.
The pkg and idx files are used to define the pathlist (in 3D).
This document details the binary formats of these files and thus the associated XML files.
The types used are:
int32 32-bit integer int64 64-bit integer smallint 16-bit integer Single 1.5 x 10^-45 .. 3.4 x 10^38 4-byte real number Double 5.0 x 10^-324 .. 1.7 x 10^308 8-byte real number Pstring string : A byte indicating the length of the string followed by characters
The altitudes are important, they allow the paths to float above the terrain, otherwise the disappear within the mountains.
wwb Format
The file begins with a 32-bit integer containing the number of entries in the file. The file continues with a series of entries consisting of a float latitude and float longitude.
int32 number of pairs (latitude, longitude) in the file // entry 1 single latitude single longitude // entry 2 single latitude single longitude
IDX Format
The file begins with the number of wwb files associated in a 32-bit integer. Next is an entry for each wwb file. Each entry consists of a string, the west, south, east, and north limits in a double, and a 64-bit integer for the offset of the data in the pkg file.
int32 Number of wwb files = Number of groups in this package // wwb file 1 (wwb offset 1) PString name of a wwb file, a string double west double south double east double north Int64 offset wwb 1 = offset of data in pkg file // wwb file 2 (wwb offset 2) PString name of a wwb file, a string double west double south double east double north Int64 offset wwb 1 = offset of data in pkg file // wwb file 3 (wwb offset 3) ...
pkg format
The file contains a list of the entries containing the coordinates of each of the associated wwb files. Every description starts with a 32-bit number indicating the number of entries in the section, followed by the number of elements per entry (3 for latitude, longitude and altitude). Next are the list of entries (lat, long, h).
// wwb file 1 (wwb offset 1) int32 number of entries (lat, long, h) byte number of elements per entry = 3 (lat, long, h) // entry 1 double lat double long smallint h (16 bits) // entry 2 double lat double long smallint h (16 bits) ... // wwb file 2 (wwb 2) int32 number of entries (lat, long, h) byte number of elements per entry = 3 (lat, long, h) // entry 1 double lat double long smallint h (16 bits) // entry 2 double lat double long smallint h (16 bits) ... // wwb file 3 ...
Example of the XML file associated with a pathlist
<?xml version="1.0" encoding="UTF-8"?> <LayerSet Name="" ShowOnlyOneLayer="false" ShowAtStartup="false" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="C:\WorldWind\bin\Debug\Configuration\EarthLayers\LayerSet.xsd"> <PathList ShowAtStartup="true"> <Name>Trail</Name> <DistanceAboveSurface>1000</DistanceAboveSurface> <MinDisplayAltitude>0</MinDisplayAltitude> <MaxDisplayAltitude>6000000</MaxDisplayAltitude> <PathsDirectory>Data\WorldWindow.Earth\monchemin</PathsDirectory> <WinColorName>Cyan</WinColorName> </PathList>
The folder Data\WorldWindow.Earth\monchemin contains a file pathlist.pkg and a file pathlist.idx that define the path.
