LYT File Format - NickHugi/PyKotor GitHub Wiki

KotOR LYT File Format Documentation

LYT (Layout) files define how area room models are positioned inside a module. They are plain-text descriptors that list room placements, swoop-track props, obstacles, and door hook transforms. The engine combines this data with MDL/MDX geometry to assemble the final area.

Table of Contents

Format Overview

  • LYT files are ASCII text with a deterministic order: beginlayout, optional sections, then donelayout.
  • Every section declares a count and then lists entries on subsequent lines.
  • All implementations (vendor/reone, vendor/xoreos, vendor/KotOR.js, vendor/Kotor.NET) parse identical tokens; KotOR-Unity mirrors the same structure.

Implementation: Libraries/PyKotor/src/pykotor/resource/formats/lyt/

Syntax

beginlayout
roomcount <N>
  <room_model> <x> <y> <z>
trackcount <N>
  <track_model> <x> <y> <z>
obstaclecount <N>
  <obstacle_model> <x> <y> <z>
doorhookcount <N>
  <room_name> <door_name> <x> <y> <z> <qx> <qy> <qz> <qw> [optional floats]
donelayout

Room Definitions

Token Description
roomcount Declares how many rooms follow.
<room_model> ResRef of the MDL/MDX/WOK triple (max 16 chars, no spaces).
<x y z> World-space position for the room’s origin.

Rooms are case-insensitive; PyKotor lowercases entries for caching and resource lookup.

Reference: vendor/reone/src/libs/resource/format/lytreader.cpp:37-77

Track Definitions

Tracks are only used by swoop racing layouts. Each entry contains the model ResRef plus its position. The section is optional.

Reference: vendor/KotOR.js/src/resource/LYTObject.ts:73-83

Obstacle Definitions

Mirrors the track format; typically only present in KotOR II racing modules. Most shipped KotOR I layouts omit this block entirely.

Door Hooks

Door hooks bind door models (DYN or placeable) to rooms. Each entry contains:

Token Description
<room_name> Target room (must match a roomcount entry)
<door_name> Hook identifier (used in module files)
<x y z> Position of door origin
<qx qy qz qw> Quaternion orientation
[optional floats] Some builds (notably xoreos/KotOR-Unity) record five extra floats; PyKotor ignores them while preserving compatibility.

Reference: vendor/xoreos/src/aurora/lytfile.cpp:161-200

Coordinate System

  • Units are meters in the same left-handed coordinate system as MDL models.
  • PyKotor validates that room ResRefs and hook targets are lowercase and conform to resource naming restrictions.
  • The engine expects rooms to be pre-aligned so that adjoining doors share positions/rotations; VIS files then control visibility between those rooms.

Reference: Libraries/PyKotor/src/pykotor/resource/formats/lyt/lyt_data.py:150-267

Implementation Details

All of the projects listed above agree on the plain-text token sequence; KotOR-Unity and NorthernLights consume the same format without introducing additional metadata.

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