Field jump — how the game moves between maps

Field jump — how the game moves between maps

The complete path that takes the party from one field to another (or to the world map / a disc change): what triggers a jump, how the destination is described, how a field ID resolves to a filename, and how the party is placed on arrival. Addresses for FF8_EN.exe, image base 0x400000. The field runtime that consumes the loaded files is on Field rendering and collision.

Jump request globals

Every jump, whatever triggered it, fills the same handful of globals and lets the module handler act on them:

Global	Address	Meaning
`globalFieldNextModuleID`	see table below	Destination module: 1 = field, 6 = disc change (cdcheck), 7 = world map, 4 = intro/credits
`MenuState_opcode_menu_id`	—	Multi-purpose “next module parameter”; for a field jump = destination field ID
`wm2field_FieldX` / `FieldY`	see table below	Spawn X/Y on the destination field (0x7FFF = keep current position)
`wm2field_FieldZ`	—	Destination walkmesh triangle / Z
`wm2field_FieldTarget`	—	Facing direction on arrival

Triggers

Field script opcodes

Field scripts pop their arguments off the entity script stack and set the globals:

Opcode	Function	Behaviour
`MAPJUMP`	0x521A20	Jump to field ID with spawn X, Y, triangle (arg) and facing
`MAPJUMP0`	0x521C30	Jump keeping the party’s current position (X=Y=0x7FFF), target 0
`MAPJUMP3`	0x521AC0	Like MAPJUMP with an extra parameter word
`WORLDMAPJUMP`	0x521820	Sets `globalFieldNextModuleID`=7 → world map (toggles the savemap save-enable flag)
`DISCJUMP`	0x521B70	Sets `globalFieldNextModuleID`=6 → disc-change screen, disables the menu

Gateways (walked field exits)

Field_Collision_CheckGatewayCrossing tests the 12 gateway records in the .inf file (.inf+100, 32 bytes each). A gateway fires when the player is within touch radius of its line and the cross-product sign against the line flips between the previous and current position. On firing it sets the same globals from the record: destination field ID (< 0x48 routes to the world map = module 7, otherwise a field = module 1), spawn X/Y, triangle and facing. See the gateway record layout on the rendering/collision page.

World map → field

Boarding an entrance on the world map calls World_FindFieldEntrance, whose returned index selects a record in wm2field.tbl. The module handler (FFModuleHandler_main_loop) reads that record to fill CURRENT_FIELD_ID + spawn globals, then enters the field.

wm2field.tbl record format

wm2field.tbl is an array of 24-byte records indexed by entrance ID:

Offset	Size	Field
+0	u16	spawn X
+2	u16	spawn Y
+4	u16	walkmesh triangle / Z
+6	u16	destination field ID
+8	u8	facing direction

(The table is loaded near the module handler; the same 24-byte stride is used by the world-map field-entrance path.)

Field ID → filename: the maplist

Field_LoadResources resolves the numeric field ID to a field name through mapdata\maplist — a plain newline-separated text file, one field name per line:

A field’s ID is simply its 0-based line number in maplist.

The loader (part of Field_LoadResources) reads maplist into a buffer and walks it: it skips control characters (< 16, i.e. CR/LF) between lines, counting lines until the count equals CURRENT_FIELD_ID, then copies that line’s printable characters (> 16) as CURRENT_FIELD_NAME. That name builds the field archive path and each section file is loaded:

.inf (gateways/triggers) · .ca (camera) · .id (walkmesh) · .map + .mim (background) · .msk (movie mask) · .rat / .mrt (encounter) · .msd (dialog) · .gsm / .sfx (sound) · .pmd (particles) · .jsm (scripts) · .pcb (extra).

Where the field ID comes from

CURRENT_FIELD_ID is set from different sources depending on the trigger:

World → field: the wm2field.tbl record’s field-ID word (in FFModuleHandler_main_loop).
Field → field / disc jump: MenuState_opcode_menu_id, which the jump opcode set (copied to CURRENT_FIELD_ID on field re-entry; the disc path copies it in FFModuleHandler_main_loop after the disc check).
A few hardcoded returns exist (e.g. field 0x4B on a specific game-over return).

End-to-end flow

flowchart TD
    A[Trigger: MAPJUMP opcode / gateway crossing / world-map entrance] --> B[Set globalFieldNextModuleID + field ID + spawn X/Y/triangle/facing]
    B --> C[FFModuleHandler_main_loop reads globalFieldNextModuleID]
    C -->|1 field| D[CURRENT_FIELD_ID set<br>from wm2field.tbl or MenuState_opcode_menu_id]
    C -->|7 world map| W[worldmap_init]
    C -->|6 disc| X[cdcheck screen]
    D --> E[Field_LoadResources: maplist line = field ID -> field name]
    E --> F[Load NAME.fs sections .inf/.ca/.id/.map/.mim/...]
    F --> G[Field_Walkmesh_PlaceEntitiesOnLoad:<br>spawn party at wm2field_FieldX/Y/triangle/facing<br>0x7FFF X/Y = keep position]
    G --> H[Field running]

Function addresses

Function	Address	Description
`Field_Collision_CheckGatewayCrossing`	0x477980	Gateway line-crossing test
`SCRIPT_MAPJUMP`	0x521A20	MAPJUMP field-script opcode
`SCRIPT_MAPJUMP0`	0x521C30	MAPJUMP0 field-script opcode
`SCRIPT_MAPJUMP3`	0x521AC0	MAPJUMP3 field-script opcode
`SCRIPT_WORLDMAPJUMP`	0x521820	WORLDMAPJUMP field-script opcode
`SCRIPT_DISCJUMP`	0x521B70	DISCJUMP field-script opcode (renamed from `DISCJUMP` in the community IDB)
`FFModuleHandler_main_loop`	0x4706B0	Module switch handler (also resolves `wm2field.tbl` records and copies `CURRENT_FIELD_ID`)
`Field_LoadResources`	0x471010	Resolves field ID to name via maplist and loads field archive sections
`Field_Walkmesh_PlaceEntitiesOnLoad`	0x477C90	Spawns entities at the destination triangle
`jumpFromWorldmapToField`	0x52BC00	World-map-to-field jump handler
`globalFieldNextModuleID`	0x1CE4760	Global variable/data, not a function — destination module id
`CURRENT_FIELD_ID`	0x1CD2FC0	Global variable/data, not a function — active field ID
`CURRENT_FIELD_NAME`	0x1CD2DB0	Global variable/data, not a function — active field name
`wm2field_FieldX`	0x1CE4764	Global variable/data, not a function — spawn X on destination field

Addresses are for FF8_EN.exe (2000 PC release) as mapped in IDA (image base 0x400000).