The dotXSI format (typically referred to simply as XSI, an acronym for X|SoftImage) is one of three model formats usable by Battlezone II's engine. The format is related to the DirectX-based .X format , which Battlezone II is also capable of interpreting. When an XSI model (or an X model, though the DirectX format is not fully compatible with the game) is read for the first time, the game munges it to a MSH file for more efficient use.
The models used in Battlezone II were created using Softimage 3D, a 3D modelling program first released in 1988 and famously used to animate the dinosaurs in Jurassic Park. Its parent company Softimage was acquired by Microsoft in 1994 and re-branded Softimge|3D, who in turn sold Softimage to Avid Technology in 1998. Softimage|3D was discontinued in 2002, having been gradually replaced by Softimate|XSI over the preceeding two years. In 2008, Softimage's 3D and animation assets were acquired by Autodesk, and the re-branded Autodesk Softimage package is due to be discontinued in 2015.
Modern versions of the .XSI file format are incompatible with the Battlezone II engine, as the version its models use (dotXSI) was introduced with Softimage|3D 3.8, released on July 20th 1998.
XSI models are composed of parts called frames laid out in a hierarchy structure. Each frame can contain several other frames or meshes, the latter of which contain vertex co-ordinates that make up the model structure and reference a material for use as a texture. Several frames with specific names are required in certain types of models, including hardpoints which are used for indicating particular locations on a model for use in-game (such as weapon points and the cockpit).
Despite Softimage|3D having been discontinued, many mod developers have found their own ways of creating and editing XSI files. A few of the tools used are listed below.
- BZ2ME: Specially created by John Kempen for use with the dotXSI format, the Battlezone II Model Editor is not overly reliable (particularly when dealing with animations). Capable only of basic copy-paste modelling. Also occasionally known as ThreeD.
- 3D Exploration: A viewer only, but provides greater functionality in this regard than ThreeD. Capable of displying animations correctly, though has some difficulties with older XSI models such as those from the Battlezone II Demo. DeepExploration, a CAD program by the same developer, is also used (though more rarely).
- 3DS Max: Another Autodesk product, 3DS Max is the most commonly used modelling package amongst the Battlezone II community. Importing an exporting models to it involves several format conversions with which ThreeD and 3DEx are typically helpful.
- Notepad: Notepad programs are also capable of opening dotXSI files due to their ASCII encoding. The resulting file is difficult to read to inexperienced users, but advanced users can use a notepad program to modify parts of a model as required, with swapping textures and copying parts becoming just as easy as (and more reliable than) performing the same task using ThreeD.
- Blender: A free and open-source 3D modelling application that is capable of directly exporting to Battlezone II's format of dotXSI with a community-made plugin , which can export all types of dotXSI information used by Battlezone II including bone animations. A limited blender importer is also available.