Revision as of 10:51, 25 September 2012

KIND Track provides the sole asset kind for spline-based assets. Contrary to the name, assets of this kind include simple track, multitrack, bridges, tunnels, hedges, roads, walls, embankments, local power lines, high-voltage power lines, and so on. Assets of this kind use a rendering technique previously known as "stitched track". Now that all other spline rendering is obsolete, it is simply known as "track".

KIND Hierarchy

Parent Classes

• KIND TrainzBaseSpec

Child Classes

• none

Supported Tags

The KIND Track config.txt file supports the following tags. Each tag is show here with its default value.

mesh-table
{
}
track
{
}
endcap-prev
{
}
endcap-next
{
}
attached-splines
{
}
season-selector
{
}
carrate 0
isroad 0
isfreeway 0
is_silent 0
numlanes 0
istrack 0
istunnel 0
surveyor-only 0
visible-on-minimap (opposite of surveyor-only)
track-sound
{
}
traffic-speed 10.0
tunnel-roof-height 0.0

mesh-table

The "mesh-table" Container provides details about the track and end-cap meshes which comprise this asset. Most advanced mesh-table options are not available for use at the current time. The important thing is to specify the meshes.

track

The "track" tag is compulsory and determines how the spline geometry is formed from meshes. It is specified as a Track Part Container.

attached-splines

The "attached-splines" container provides a mechanism for having child splines attached which follow the shape of this parent spline at a slightly offset. Attached splines are used where a spline with one set of rendering or functional behaviour needs to be coupled with a spline with a different set of rendering or functional behaviours. For example, a bridge (scenery) with attached track (functional), or a set of pylons (no stretching or shearing) with some wires strung between them (shearing and stretching to fit.) The attached splines may be render-only splines which effectively don't exist beyond of their rendering behaviour, or they may be fully functional splines whose only specialty is that they move and delete with their parent.

endcap-prev & endcap-next

The "endcap-prev" and "endcap-next" tags are specified in the same way, but are not compulsory. If present, these end caps are inserted past the ends of the spline in each direction unless the spline flows onto another spline of the same type. This allows the content creator to "seal" the spline geometry without having to introduce inefficient sealing polygons at each subdivision. The endcaps obey the normal fit-to-spline behavior except that they continue straight in the instantaneous direction of the end of the spline. The endcaps inherit their default settings from the asset's "track" tag but any individual values may be overridden as desired.

Season-selector

The "Season-selector" container allows for the selection of a season index, which may be used by the "track-lod-tree" container.

carrate

(Only applicable to splines which have 'isroad' set.)

The game waits between 1x to 3x this decimal value between generating carz on this road.

isroad

If set (1), splines of this type are considered roads. Roads support the generation of Carz. Roads are flagged as blocked by KIND MOCrossing while the crossing gate is closed. Road splines can generally be joined, even if they are different assets.

If not otherwise specified, assets with the 'isroad' tag set are members of the "Road Spline Group" <kuid:30501:100045>.

isfreeway

(Only applicable to splines which have 'isroad' set.)

If set (1), this boolean tag causes a multilane road to act as a freeway. This allows carz to change lanes at will, and causes all traffic to flow in the spline's forward direction only. Overtaking is still allowed on non-freeway roads.

is_silent

(Only applicable to splines which have 'istrack' set.)

If set (1), this boolean tag disables the playing of per-axle sounds for vehicles on the spline.

numlanes

(Only applicable to splines which have 'isroad' set.)

Defines the number of carz lanes on a road. Each lane is considered to be 1.7 meters wide. If the road is a freeway, all traffic flows in the same direction. TBD: What, if anything, does this mean for a non-freeway road?

istrack

If set (1), this boolean tag causes the spline to be treated as a "track", meaning that trains can be expected to run on the spline.

This affects the visibility of the spline on the minimap, where the spline assets shows up in the surveyor pickers, which surveyor tools can operator on the asset, and whether automatic junction placement is enabled.

Track splines can generally be joined, even if they are different assets.

If not otherwise specified, assets with the 'istrack' tag set are members of the "Track Spline Group" <kuid:30501:100043>.

istunnel

Tunnel splines attempt to curve such that the spline terminates at a 45° angle increment. This helps ensure that entrance holes can be successfully created through the terrain mesh.

Tunnel splines have slightly modified editing semantics in Surveyor. Vertex markers are visible in different conditions. Smoothing the ground around a tunnel is not permitted. The tunnel spline always follows the spline gradient rather than reacting to the ground height.

Some types of derailment are disabled while in a tunnel because the resultant user experience would be poor due to inter-penentration of the tunnel and terrain by the train vehicles and the player's camera.

The script function Vehicle.IsInTunnel() returns 'true' while a vehicle's origin is on a tunnel spline.

If the user is in 'external' or 'auto tracking' camera mode while the camera target is in a tunnel, the camera changes to "tunnel external" mode instead.

While the camera target is in a tunnel, environmental sounds are reduced to 50% volume.

Some types of vehicle particle emitter are disabled while the vehicle is in a tunnel.

If not otherwise specified, assets with the 'istunnel' tag set are members of the "Tunnel Spline Group" <kuid:30501:100044>.

surveyor-only

If set (1), this boolean value causes the asset to be invisible and non-functional in Driver. This is typically used for splines which provide editing assistance, such as templates, markers or rulers.

visible-on-minimap

If clear (0), hides this spline from the minimap. Splines with non-render-only children are never shown on the minimap.

track-sound

TBD.

traffic-speed

(Only applicable to splines which have 'isroad' set.) Defines the carz speed limit of the road in meters per second. Carz currently travel at up to 80%-110% (depending on the car) of the speed limit, except when overtaking. This tag does not relate to trains in any way.

tunnel-roof-height

(Only applicable to splines which have 'istunnel' set.) Used by tunnels to determine the roof height in meters allowed by the terrain hole. If less than or equal to zero, no terrain holes are generated.

Base mesh

One of each base mesh is required. Several variants of each may be present, in which case they are selected in a position-dependant pseudo-random fashion. A single material (ie. single texture) must be used for all base meshes (not one for each.)

Base meshes may use either alpha masking (1-bit alpha) or alpha blending, however any alpha blends will not be sorted (not against other polygons in the track itself, nor against other alpha-blended polygons in the scene.) For this reason, alpha blending should only be used low to the ground such that a line from the camera to the mesh will pass through no other alpha-blended object before reaching the ground. Normal z-buffer behavior will apply to both alpha-blended and alpha-masked base meshes.

Base meshes make use of a normal map and a single high resolution diffuse texture.

The base mesh pieces are modelled in such that any type may fit to any other without an obvious seam. Pieces are not required to be symmetrical, as they will never be rotated with respect to the previous piece.

• Extreme detail mesh - used for close-ups. 1000 polys per 2m segment.

• High detail mesh - used at close range. 200 polys per 2m segment.

• Mid detail mesh - used at mid range. 100 polys per 10m segment.

• Low detail mesh - used at far range. 6 polys per 10m segment. Tracks are textured onto the ballast, rather than polygon-modelled.

• Initial end-cap - used at the start of the spline. 100 polys.

• Final end-cap - used at the end of the spline. 100 polys.

The end-caps provide any polygons necessary to "close" the spline so that it does not appear hollow when seen from end-on. The other meshes do not include any such polygons. The end-caps are used wherever a transition is made from one track type to another, or where the track begins or ends abruptly.

The length of each mesh is specified independantly. It is recommended that each is made as long as reasonably possible within the alloted polygon budget.

The top of the rail mesh can be no higher than 300mm. Any higher and the wheel rail head interface will not display properly

Spline Placement

Base meshes may be specified to follow their placement spline as closely as possible (previously: bendy) or to stay straight but shear to prevent seams.

Vertices on the mesh may fall into one of two height categories:

• Grounded - The vertex positioning is based on the ground height.
• Spline - The vertex positioning is based on the placement spline.

The height category of a vertex is determined from it's relative height within the mesh - if it is less than or equal to the per-mesh-specified grounding height, it is considered grounded.

Performance

Actual performance will vary based on the following factors:

• Distance at which the High-detail LODs drop out. Generally this should be extremely close.
• Number of polygons in the lower LODs. Generally this should be very low.
• Number of materials used. Ideally, a single material is used for all meshes, rather than one or more per mesh.
• Length of each mesh (longer is better).
• Efficiency of the "track-lod-tree" container.
• User-customisable detail settings.
• etc.

Downloads

• Media:TS2009-track.zip - The MAX source for the Auran TS2009 example track. Distributed from the TrainzDev site for education purposes only. No license for the reproduction or redistribution of the included model or textures is granted.

Related Links

• "track-lod-tree" container
• Modeling Splines
• Track Part Container

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