This document describes a draft version of the lrb spec (version 0), files in this version can't be expected to always be in the correct format due to the version not bumping to 1 until the spec is finalized.

This Other Document describes the initial idea for the format, while this document tries to finalize the spec before a proper version 1 is declared.

some definitions & assumptions are borrowed from this document. this includes how type names are written and what they mean (this is especially important for strings which can be written in a number of ways).

Mod Table

at the start of a .lrb file, the following is written:

name	type	description
magic number	byte[3]	should always be 0x4C 0x52 0x42 (LRB).
lrb version	u8	for this spec, value should be 0.
mod count	u16	the amount of entries in the mod table
[mod entries]	modtable_entry[mod count]	list of entries to the mod table, each one reading as described below

Mod Table Entry

for each mod in the mod table, the following is written:

name	type	description
name	string with u8 length and utf-8 encoding	the name of the mod
version	u16	starts at 0 and increments with each breaking change to a mod, such that an implementation can know if it's current version of a mod will properly load the file.
modflags	u8	see Modflags
data pointer	u64	pointer to the start of this mod's data. may be omitted depending on modflags
data length	u64	the length of the section of data this mod stores in the track, in bytes. may be omitted depending on modflags

Modflags

the modflags are a single byte with individual bits indicating certain properties of a mod:

000EDCBA

symbol	name	description
A	required	should be set to 1 if the mod is required. this means that it is not safe to ignore the mod.
B	physics	can be set to 1 to indicate to the loading implementation that the absence of an optional mod will break physics compatibility if missing (but might not have any effect on the track otherwise)
C	camera	can be set to 1 to indicate to the loading implementation that the absence of an optional mod will break camera compatibility if missing (and therefore animations)
D	scenery	can be set to 1 to indicate to the loading implementation that the absence of an optional mod will break scenery compatibility if missing (given an arbitrary camera position, can you render and get the same result with/without the mod?)
E	extra data	a value of 1 indicates the presence of the data pointer & length in the modtable entry. otherwise this mod's only data is it's presence in the modtable.
000	unused	written as zeros and not used in any way when loading.