• Alias - An asset which takes it's mesh from another asset, but replaces one or more of the original textures with locally provided ones. Commonly used to reskin an asset.
  • Note: Trainz 2009 (version 2.9) onwards do not accept aliased assets in Content Manager, though they still work in the game.
• Alpha blending - The process of using an opacity setting or texture alpha channel to allow partial transparency. Alpha blending is a hardware operation, however by itself blending does not combine well with a traditional hardware depth-buffer technique.
  • The end result is that multiple overlapping layers of alpha blending will not be rendered in the physically correct order without some alternative non-hardware-accelerated techniques. Such techniques should be avoided due to the associated performance losses.
  • In short: use alpha blending sparingly, and do not apply an alpha-blended material to polygons which could do without.
• Alpha masking - The process of using a texture alpha channel to "mask out" parts of the texture, allowing arbitrary see-through areas on the texture. Unlike alpha blending, alpha masking does not allow semi-transparent areas - each resultant texel is either fully textured, or fully transparent. Alpha masking is a fully hardware-accelerated technique, and so acceptable.
• Asset - A single item of content in the Trainz environment, consisting of a config.txt file and any associated resource files.
  • Sometimes, even frequently,... used (incorrectly) interchangeably with 'content'; technically, content is an asset included in a route or session—until then an asset is an potential content item.
  • Each asset is uniquely identified by its KUID. An asset may reference any number of dependencies which are required for correct operation.
• Blender - A free Modeling tool with similar functionality to the commercial MAX software.
• Bogey - Asset type used to represent wheels and suspension components. Used for anything that needs to rotate as the train moves along the track (e.g. wheels), or move (by rotation or translation) to match the angle and position of the track (e.g. subframe and suspension components). In the US this is normally referred to as a truck, and in the UK as a bogie.
• Bump mapping - Another term for Normal mapping.

• Cab / Cabin / Interior - Asset made to represent the inside of an object, typically a Vehicle.
• Content Manager - Program for querying and editing the Trainz Asset Database.
  • Common tasks performed with Content Manager include downloading, uploading, installing, editing, archiving, error trapping (testing for, generation of) and removing content.
• Dependency - An asset which is required by this asset in order to function properly.
• Dependent - An asset which requires this asset in order to function properly.∅
• Geometry - A three-dimensional mesh, without any related textures or material properties.
• Indices - Each triangle has three indices. Each index is a reference to a vertex. (Vertices can be shared between multiple polygons).
• KUID - Unique identifier for a specific Trainz asset. Consists of Creator ID, Content ID and Version number fields.
• KUID Table - The kuid-table container of an asset's config.txt file. Used to specify dependencies.
• Level-Of-Detail (LOD) - A technique where an object (typically a mesh) is built with a number of variations which look as close as possible to identical, but which trade off quality as distance from the viewing point increases and that aids rendering performance to differing degrees.
  • The Auran JET graphics engine selects between the various levels at runtime based on metrics such as distance from the observer.
  • For textures, mip-mapping serves a similar purpose without requiring manual attention.
  • All medium-to-high-detail meshes should supply LOD variants. LM.txt_files are used for LOD on moving/animated models.
• Material - A named object with a specific material type in combination with its necessary parameters and textures.
• MAX / 3D Studio Max, or obsolescent Gmax once bundled with early Trainz retail releases - The commercial Modeling tool used and supported by Auran.

• Mesh - A three-dimensional model used in the game environment. The word mesh is often used to refer to a specific game file containing the three-dimensional geometry without related properties such as the model's textures.
• Mesh Library - An asset which other assets use. These assets refer to the mesh library by KUID, using a 'mesh-asset' tag in their mesh table. Nothing special is needed for an asset to be a mesh library, it just has to contain mesh files.
• Mesh stitching - A runtime optimization process which combines multiple individual mesh instances into a single draw call for performance reasons. This results in higher performance with no visible changes.
• Mesh Table - The "mesh-table" Container of an asset's config.txt file.
• Mip mapping] - Process to reduce texture detail for objects in the distance, or at a sharp angle to the camera. Used to avoid problems with aliasing (flicker), which can occur where the texture is of comparable or higher detail than the display equipment.
• Model - A three-dimensional definition of an virtual 3D object, built in a special modeling package such as Blender or Max. The word model is often used to describe the concept of a three-dimensional object including properties such as its textures.
• Normal mapping - A more advanced form of texture mapping which allows per-pixel control over the lighting conditions on the target geometry. Among other benefits, this technique allows a content creator to define small bumps and grooves in a surface in addition to simple coloration.
• Obsolete - An asset is obsolete if it has been replaced by a newer version with newer technology models and definitions, breaking the asset in part for a new "Trainz-build" tag (version).
  • A container type or tag in a KIND is obsolete because the programmers say so—because they have a real need to change the data structure in a new Trainz advance, normally without warning the user community first.
• String Table - The "String-table" container of an asset's config.txt file. Used for localization strings (i.e. anything that will be displayed to the user).
• Pixel - One individual point on a texture image, consisting of red, green, blue and alpha components (e.g. a texture size of 512 pixels by 512 pixels). May also refer to one individual point within a display (e.g. a display size of 1024 pixels by 768 pixels).
• Polygons - In modeling terms, a polygon is always a triangle. (Please note, this is different from the 3DSMax definition).

• Render call / Draw call - A single hardware rendering operation. This is an important concept when performance is a concern, as there is a substantial performance overhead to each draw call. By minimizing the number of draw calls, the same scene can be rendered at a notably higher frame rate. Each draw call associates one material with some quantity of vertices and indices.
• Route / Layout / Map - Asset created in Surveyor, consisting of a textured landscape and one or more Layers containing scenery objects, splines, trackside objects, Vehicles, etc.
• Scenery / Map object - A scenery object is an instance of an asset that is placed in Surveyor at a given location and orientation.
• Session - Asset created in surveyor, which extends a map by placing on it additional layers of objects - commonly Vehicles, but any scenery object, spline, trackside object, etc, can also be added. The Session also contains all the saved script data from any asset in the combination of map and session.
• Specular lighting - Lighting effects that vary dependent on the angle of incident light.
• Spline - A continuous linear 3D model such as a hedge, a fence, a road, or a track. Splines are placed in Surveyor as a series of spline control points and the geometry is built in a smoothed path between the control points.
• Texel - One texture pixel, once mapped onto a 3D Model and rendered in a scene. Does not correspond to one screen pixel.
• Texture - A two-dimensional image used for texture mapping.
• Texture Sharing - When two or more meshes in the same asset (which may be a mesh library, and thus used by many assets) use the same material and texture. Trainz can then use mesh stitching to render them in the same draw call, with corresponding performance improvements.

• Trackside object - A trackside object is a specialisation of a scenery object that is placed attached to a spline. When the spline is moved, the trackside object is also moved.
• TrainzScript / GameScript - Used interchangeably, these terms refer to the Trainz scripting language.
• Trainz Asset Database - Contains all the metadata information about Trainz content. Editable through Content Manager and TrainzUtil.
• TrainzUtil - Command line tool to query and edit the Trainz Asset Database.
• Trainz Native Interface - TBD
• Triangles - Three vertices (or specifically, three indices) form a triangle. The triangle is the basic unit of a mesh geometry.
• Vehicle - All assets which can be placed into a train (consist). Includes locomotives. Not to be confused with road cars, which are actually Trackside objects (as they are attached to roads).
• Vertices - The individual three-dimensional (x, y, z) coordinates that form the corner points of triangles in a mesh geometry.

File Formats

• config.txt file
• .texture.txt file
• .texture file
• .pm file
• .im file
• .lm file
• .gs file
• .gse file
• .cdp file
• .cmpa file

Abbreviations