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NotRoadType Spec

Essential

• split RoadType to StreetType and TramType
• per tile, one StreetType and one TramType may be present
• they can coexist on the same tile in some cases, but do not influence each other
• construction tools for StreetType and TramType are independent
• adding/removing/converting StreetType on a tile does not affect TramType for tile and vice-versa
• subtypes
  • up to 15 StreetType subtypes and 15 TramType subtypes (implementation detail: uses 4 bits each, uses 8 bits free in m4)
• drawing
  • (lowest) Ground -> StreetType -> TramType -> Sidewalks + Decoration -> StreetTypeCatenary -> TramTypeCatenary (highest)
  • drawing of rail crossings may or may not be fixed (road tile is enforced for tram crossings currently, this looked non-trivial to fix when I tried)
  • methods may be provided to enable more control over appearance, e.g. snow above snowline etc
• catenary
  • both StreetType and TramType can provide catenary on a tile (implementation detail: flag or cb returning sprites)
  • vehicle power on a tile is determined by vehicle against subtype label, unrelated to drawing of catenary sprites
  • there is sophisticated handling of rail catenary to preserve continuity where railtypes cross, something similar needs to be provided for NotRoadTypes
• converting between subtypes
  • a convert tool is needed, similar to rail conversion
  • this will need to consider ownership carefully
    • too restrictive = can’t overbuild current subtype in towns
    • too permissive = deliberate or accidental breaking of existing routes by overbuilding current subtype
• drive-in stops:
  • behaviour of articulated vehicles and trams unchanged, can’t use drive-in stops
  • catenary needs to be provided for StreetType drive-in stops
• vehicles
  • vehicles are StreetType XOR TramType (bool flag)
  • each subtype has a label
  • vehicle compatibility with a subtype is determined by label
  • vehicle may determine some properties by subtype (power, possibly others)
• overtaking: out of scope
• newgrf author considerations
  • user should be able to see whether catenary exists for road, tram, or both
  • authors will need to draw catenary carefully to avoid it looking bad when StreetType and RoadType catenary are combined on a tile

Optional (proposed by frosch)

• split global toolbar to ‘road’ (StreetType) and ‘light rail’ (TramType)
• this makes the distinction between the transport types obvious
• in this way it’s clear that a tile can have
  • 1 type of rail
  • 1 type of road
  • 1 type of light rail
• unknown: would the various vehicle menus, station menus etc also be split for ‘road’ and ‘light rail’?  !