Romlist

Each map has a [mapname].romlist.zlb file in the root of the disc. This file is a ZLB-compressed list of objects on the map.

Entries in this list are variable length, following this format:

Offset	Type	Name	Description
000000	s16	type	Object type (ObjDef)
000002	u8	size	Entry length in (4-byte) words
000003	u8	acts0	Bitmask of map acts to load in
000004	u8	loadFlags	Loading flags
000005	u8	acts1	Bitmask of map acts to load in
000006	u8	bound	Load if distance to player is less than (bound * 8)
000007	u8	cullDist	Cull object when distance to player is less than (cullDist * 8)
000008	vec3f	position	Object position
000014	u32	id	Unique ID
000018	varies	-	Parameters depending on object type

(XXX is it cullDist * 80 or was that a typo?)

The object type is translated:

• If it's positive, the corresponding entry in OBJINDEX.bin (which is simply an array of s16) is used.
• Otherwise, the absolute value is used.

The resulting ID is an index into OBJECTS.tab, which gives the offset in OBJECTS.bin of the ObjectFileStruct.

(Why are these in the disc root, instead of the map directory? No idea.)

The unique ID is used to persist the object in the save file. The coordinates of up to 63 objects can be saved using this ID. This ID is also used to look up the object in scripting. Every object in the romlist files has a unique ID. (Exception: Multiple objects in unused maps have the ID 0xC5D.) Dynamically created objects have ID 0xFFFFFFFF.

Each bit of acts0 and acts1 corresponds to an act number:

Bit	Act1	2	3	4	5	6	7	8	9	10	11	12	13	14	15
acts0	01	02	04	08	10	20	40	80
acts1									80	40	20	10	08	04	02

• If the given bit is not set, the object will load in this act.
• The lowest bit of acts1 appears to be unused.
• Act 0 loads all objects.
• Act -1 loads no objects, but since the act number ranges from 0 to 15, this is impossible.
• Some object types might beusing these fields for some other purpose, since they seem to have arbitrary, strange values here, and LoadFlags allow bypassing this system.

LoadFlags:

Flag	Name	Description
0x01	isLevelObject	Load if act bits allow
0x02	isManualLoad	Always load - used for dynamically created objects
0x04	OnlyLoadIfNearPlayer	Use bound
0x08	?	?
0x10	loadForOtherMap	Load for a different map ID
0x20	isBlockObject	Load regardless of position
0x40	?	?
0x80	?	?

(names are inferred from debug messages)

Refer to dlls.xml for object-specific parameters. (Warning: very large file)

OBJINDEX.bin

An array of one s16 per object ID. This maps the IDs given in romlist files to indices into OBJECTS.bin. Unused entries map to -1.

A romlist can use negative object IDs to bypass this mapping. (This is not a bug; the game explicitly checks for this case. This applies to most such index mapping, not only objects.)

It's not clear why this mapping is done. It makes sense for other assets such as models, where each map has its own copy (the mapping tells which asset ID is at which entry in the map's file); perhaps at one time, each map had a copy of OBJECTS.bin as well?