Rollingcats Transit Expansion

First public beta.

Track geometry

• Four path modes: native, auto Bézier, multi-point curve fitting, manual Bézier
• Vertical curves with configurable radius; gradient shown in ‰
• Cant (superelevation) — roll distributed along the track. Vehicle body, camera and the player's standing plane all follow
• Geometry analysis: curvature, minimum radius, gradient rating with suggested speed

Construction tools

• Compound creator — draw a cross-section once and sweep it along the line. Follows curves automatically and rolls with cant
• Catenary planner — places masts and contact wire along the track, with adjustable span, stagger, height and side (requires MSD)
• Route path creator, displacement tool, bridge creators (1/2/3 blocks wide)
• Parallel line copy, along-line array, manual track chains with draggable endpoint handles
• Undo: sneak + right-click air

Legacy resource pack compatibility

MTR 3.x packs lose a lot of functionality under 4.0. This release adds a compatibility layer for the migration gap. Measured across 322 community packs, loading errors dropped from 567 to 19.

• Two JS runtimes — Rhino and GraalJS, selected per pack via the engine field
• Per-function script backoff, so one bad script can't throw every frame on every car
• Time base conversion between 3.x (ticks/seconds) and 4.0 (milliseconds)
• default.png base textures matched by filename instead of exact path
• Relaxed pack_format validation for packs built against older Minecraft versions
• DOORWAY parts derived from door positions — 3.x has no such concept, MTR 4 requires it
• Built-in gangway suppressed when the pack ships its own
• Oversized textures downscaled on read

Server-side data sync

Enabled when RTE is also installed on the server. Falls back to vanilla MTR behaviour when it isn't:

• Full vehicle path — fixes average speed and ETA derived by resource packs
• Full rail set, transferred in pages
• In-viewport vehicle positions at 10 Hz with extrapolation smoothing

Other

• Resource workbench — edit vehicle resources in game, export as JSON or a self-contained resource pack
• Railway dashboard: track overlay, route colouring, A* pathfinding visualisation
• Interface built on ImGui — Cloth Config is no longer required
• 10 languages

Documentation

• Manual
• Item wiki
• JavaScript scripting manual

Known issues

• Head/tail car mirroring is wrong on some legacy packs. Root cause not identified
• Car positioning is off on some legacy packs. Unrelated to the above, also unresolved
• legacyVehicleTakeover is experimental. Geometry has been verified; visual output has not been checked item by item

Please report problems via Issues with your RTE version, mod loader, MTR version and logs/latest.log.