Terminology

This page describes some of the more common train-related, content-creation-related, and general computing terms used in the Trainz environment. Users are encouraged to add their own common terms to this page in a similar fashion. Please keep in mind that this site is dedicated to TS2009 content creation, and terms which are meaningless in this context may be removed.

General Train Terminology

• In Advance Of - Signalling term. A signal is said to be 'in advance of' something, if a driver stopped at that signal would have to drive forwards to get there.
• In Rear Of - Signalling term. A signal is said to be 'in rear of' something, if a driver stopped at that signal would have to drive backwards to get there.

TBD.

Trainz Content Creation

• TrainzScript / GameScript - Used interchangeably, these terms refer to the Trainz scripting language.
• Model - A three-dimensional 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.
• 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.
• Texture - A two-dimensional image used for texture mapping.
• Material - A named object with a specific material type in combination with its necessary parameters and textures.
• Asset - A single item of content in the Trainz environment, consisting of a config.txt file and any associated resource files. Each asset is uniquely identified by its KUID. An asset may reference any number of dependencies which are required for correct operation.
• 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.
• 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.
• 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.
• 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).
• Texel - One texture pixel, once mapped onto a 3D Model and rendered in a scene. Does not correspond to one screen pixel.
• Polygons - In modeling terms, a polygon is always a triangle. (Please note, this is different from the 3DSMax definition).
• Indices - Each triangle has three indices. Each index is a reference to a vertex. (Vertices can be shared between multiple polygons).
• Vertices - The individual three-dimensional (x, y, z) coordinates that form the corner points of triangles in a mesh geometry.
• Triangles - Three vertices (or specifically, three indices) form a triangle. The triangle is the basic unit of a mesh geometry.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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).
• 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.
• Map object / Scenery object - A scenery object is an instance of an asset that is placed in Surveyor at a given location and orientation.
• 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.
• 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.
• 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.
• 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.
• Bump mapping - Another term for Normal mapping.
• Specular lighting - Lighting effects that vary dependent on the angle of incident light.
• 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 and performance to differing degrees. The 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.
• 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
• Mesh Table - The "mesh-table" Container of an asset's config.txt file.
• 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.
• 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.
• Obsolete - An asset is obsolete if it has been replaced by a newer version.
• String Table - The string-table container of an asset's config.txt file. Used for translatable strings (i.e. anything that will be displayed to the user).
• Cab / Cabin / Interior - Asset made to represent the inside of an object, typically a Vehicle.
• MAX / 3D Studio Max - The commercial Modeling tool used and supported by Auran.
• Blender - A free Modeling tool with similar functionality to the commercial MAX software.
• Content Manager - Program for querying and editing the Trainz Asset Database. Common tasks performed with Content Manager include downloading, installing, editing, archiving and removing content.
• Geometry - A three-dimensional mesh, without any related textures or material properties.

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

• TAD - Trainz Asset Database.
• CM - Content Manager.
• LOD - Level-Of-Detail.
• IM - Indexed Mesh file format.
• PM - Progressive Mesh file format.
• LM - Level-of-detail Mesh file format.
• TNI - Trainz Native Interface.