Sweet Home 3D files format specifications like extension sh3d versus zip , jar format

[jenderek]

Hello,

some days ago i must create a floor plan. So i used interior design
application "Sweet Home 3D" version 5.7 to do this work. My created
plans are stored as files with name extension ".sh3d".

When i use TrID software (found at http://mark0.net/soft-trid-e.html) to identify SH3D files, i got "ZIP compressed archive" as file type description.

So i know foobar.sh3d is just a ZIP archive. But some examples like
SweetHome3DExample2.sh3d found in Gallery section with URL
http://www.sweethome3d.com/gallery.jsp are identified by standard Unix
file identifying command as "Java archive data (JAR)". Furthermore i got for such examples as mime type "application/java-archive" instead of standard "application/zip" for ZIP files.

After looking inside sh3d files i would describe such files as:

SH3D files are ZIP archive with first member "Home". It also seems to
contain a file "Home.xml". But i do not know if this always true.

So i wanted to know if there exist an "official" file format
specification (offset magic bytes, mime type, etc.) describing how to
distinguish from other ZIP files.

Furthermore installer for Windows version 5.7 add for eTeks Sweet Home
3D Textures Library (*.sh3t) neither description nor icon inside Windows registry. Because SH3D files are just ZIP archive, in registry
PerceivedType key should be "compressed" instead empty/missing.

thanks for hints about Sweet Home 3D files formats.

[Puybaret]

SH3D and JAR files are just ZIP files, compressed or not.

The main entry of a SH3D file is named [font=courier new]Home[/font] and contains a Java serialization of the Home class instance that describes the designed home. In old versions, this entry had to be the first one in a SH3D file.
From version 5.3, there’s also a copy of the designed home in a new entry named [font=courier new]Home.xml[/font] which respects SweetHome3D.dtd. This XML entry was added to be able to read and save SH3D files in JavaScript and other environments. This entry is read in priority when a SH3D file is opened and the [font=courier new]Home[/font] is stilll saved for compatibility with previous versions of Sweet Home 3D.

During a few more versions, I foresee to save [font=courier new]Home[/font] and [font=courier new]Home.xml[/font] in a SH3D file even if they contain similar data. This is to ensure a smooth transition with future files where [font=courier new]Home[/font] entry won’t be saved anymore. The extension of these future files will be .sh3x which is already associated with Sweet Home 3D application since version 5.3 too. Future versions will also be able to read SH3D files without a [font=courier new]Home.xml[/font] entry as long as Java deserialization will be possible with [font=courier new]Home[/font] entry.

The other entries of a SH3D file are the optional entry named [font=courier new]ContentDigests[/font] (added in version 4.4) which contains digests of home data to help repair a corrupted SH3D file, and numbered entries that contain images and 3D models used by a home.