Fight 3D resources

FGT/*.LIB, FGT/*.DAT

Everything that draws a close-combat scene: 3D meshes, scenery lists, palettes, movement and camera tables, and the sine table.

Close-combat scenes in Battle Isle 2 are drawn with small 3D meshes rather than sprites. Everything that draws them lives in the FGT/ directory: the meshes (three archives sharing a 3DOB magic), the scenery and ground lists, the palettes, the backdrops, the movement and camera tables, a sine/tangent table and the sound banks. This page describes each in turn.

Status: header, vertices, polygon topology, per-face normals, per-face colour and the moving-part table recovered and validated against all 520 records - enough to render the meshes as the game does, including the per-face shade bias, and to know which polygons are a turret and where it pivots. Every byte of the file is now accounted for. The 3DLD scene lists that place the scenery are decoded too, and groupSize records a unit's strategic member count. The conversion from strength to visible members still needs a runtime trace. The layout is accounted for; the light term, some angle drivers and three inline polygon fields remain unresolved.

ObjectHeader66 bytes3DOBchar[4]vertex_offsetu16 slot_offsetu16 face_offsetu16 trailing_offsetu16 reserved_0cu16[5]vertex_count_minus_oneu16 face_count_minus_oneu16 part_countu16 reserved_leadu8[38]Polygonsvariable sizePolygonRecord × face_countvariable sizeLayout2 B Vertices4 B Colour4 B Reserved10 B Unknown6 BVertices6 × vertex_count bytesVertex × vertex_count6 bytes eachPosition6 BFace normals6 × face_count bytesFaceNormal × face_count6 bytes eachNormal6 BParts32 × part_count + listsPartRecord × part_count32 bytes eachGeometry8 B Pivot6 B Runtime12 B Reserved6 Bvertex listsu16[]Vertex slots10 × vertex_count bytes010 bytes each

Each box is one table of a 3DOB object, in file order. The polygons start right after the header; the other tables are found by the four offsets in the header, and each line runs from an offset to the table it locates. A stack stands for the records of a table, with its count in the label. Cut blocks are not drawn to scale. Dashed blocks hold the same value in every object.

Archive	Records	Contents
`FGT/UN3D000.LIB`	240	units (`UNIT###`), animations (`ANIT###`)
`FGT/LAND000.LIB`	288	terrain objects (`LAND###`)
`FGT/LAND300.LIB`	288	terrain objects
`FGT/PAL000.LIB`	41	the fight palettes the meshes are coloured from
`FGT/LAYR000.LIB`, `LAYR300.LIB`	96 each	`3DLD` scenery layer lists
`FGT/GRND000.LIB`, `GRND300.LIB`	24 each	`3DLD` ground lists
`FGT/BACK000.LIB`	20	the raster horizon backdrops and their moons - not meshes; see Where the mountains go

Object	Size	Reads as
`AMMO001A`	2 vertices, 1 two-vertex face, steel	a tracer: a bare 320-unit line
`AMMO002A`	7 vertices, 8 faces, steel and olive	a shell, 420 units long and 30 wide
`AMMO005A`	9 vertices, 2 faces, all sky, `y = 0` throughout	a flat water splash
`AMMO006A`	16 vertices, 10 faces, steel and gold	a 110-unit ball with gold octagon caps
`AMMO050A`	12 vertices, 8 faces, entirely gold	a 120-unit ball of flame - a muzzle or impact flash

Object layout

All multi-byte integers are little-endian.

66 bytes10 fields● 8 ◐ 2 ○ 0

0x00char[4]tag ●Literal 3DOB (0x424f4433).

Tables

4 fields · 8 bytes

0x04u16vertex_offset ●byte offset of the vertex table

0x06u16slot_offset ●byte offset of the runtime vertex slots; equals trailing_offset on the 410 objects that have no parts

0x08u16face_offset ●byte offset of the face-normal table

0x0au16trailing_offset ●byte offset of the part table

Counts

3 fields · 6 bytes

0x16u16vertex_count_minus_one ●vertex count is this + 1

0x18u16face_count_minus_one ●face count is this + 1

0x1au16part_count ●first word of the 40-byte object lead; see Moving parts

Reserved

2 fields · 48 bytes

0x0cu16[5]reserved_0c ◐0 across the corpus

0x1cu8[38]reserved_lead ◐rest of the object lead; 0 across the corpus

6 bytes3 fields● 3 ◐ 0 ○ 0

0x00

Point at the bar to name a field; select it to jump to its row.

knownpartly knownunknown: investigatenamed, never setalways one valueunused bits

Position

3 fields · 6 bytes

0x00i16x ●model space

0x02i16y ●+Y is down, so up is -Y

0x04i16z ●model space

6 bytes3 fields● 3 ◐ 0 ○ 0

0x00

Point at the bar to name a field; select it to jump to its row.

knownpartly knownunknown: investigatenamed, never setalways one valueunused bits

Normal

3 fields · 6 bytes

0x00i16x ●one per polygon; a unit normal in 14-bit fixed point (16384 = 1.0)

0x02i16y ●as x

0x04i16z ●as x

variable size11 fields● 6 ◐ 2 ○ 3

Layout

1 field · 2 bytes

0x00u16record_size ●total bytes of this record; also 26 + 2*vertex_count - the fixed fields run +0x00..+0x19, then one word per vertex.

Vertices

3 fields · 4 bytes

0x02u16first_vertex_ptr ●equals the first entry of vertex_ptrs

0x0cu16vertex_count_minus_one ●polygon has this + 1 vertices

tailu16[vertex_count]vertex_ptrs ●the last vertex_count words

Colour

2 fields · 4 bytes

0x0eu16shade ●0, 32, 64, 96, 128, 160 - the polygon's colour: a base index into the fight palette, see Colour

0x14i16bias ●-8..+8, the polygon's baked shade step, see Colour

Reserved

2 fields · 10 bytes

0x04u8[8]reserved_04 ◐zero on disk

0x16u16reserved_16 ◐0 across the corpus

Unknown

3 fields · 6 bytes

0x10u16unknown_10 ○packed small byte pair; undecoded

0x12u16unknown_12 ○packed small byte pair; undecoded

0x18u16unknown_18 ○0 on 92% of faces; undecoded

32 bytes10 fields● 9 ◐ 1 ○ 0

0x00

Point at the bar to name a field; select it to jump to its row.

knownpartly knownunknown: investigatenamed, never setalways one valueunused bits

Geometry

4 fields · 8 bytes

0x00u16polygon_ptr ●file offset of the part's first polygon record

0x02u16polygon_count_minus_one ●the part owns this + 1 consecutive polygons

0x04u16vertex_list_ptr ●file offset of the part's vertex-index list

0x06u16vertex_count_minus_one ●the list holds this + 1 entries

Pivot

3 fields · 6 bytes

0x08i16pivot_x ●the axis the part turns about, in model space

0x0ai16pivot_y ●up is -Y, as everywhere else in the format

0x0ci16pivot_z ●

Runtime

2 fields · 12 bytes

0x0ei16[3]translation ●0 on disk; runtime X/Y/Z translation added after pivot rotation

0x14i16[3]angles ●runtime X/Y/Z angles; applied in Z, X, Y order; 0 on disk.

Where each slot's values sit: slot k is element k of every array above.
slot	translation	angles
A	0x0e	0x14
B	0x10	0x16
C	0x12	0x18

Reserved

1 field · 6 bytes

0x1au8[6]reserved_1a ◐0 on disk; runtime role unresolved

variable size5 fields● 4 ◐ 1 ○ 0

0x00char[4]tag ●Literal 3DLD.

Objects

1 field · 12 bytes

0x04u16[6]object_ids ●ids of the LAND objects this record may place; 0xffff/0xfffe mark unused slots

Placements

2 fields · 2 bytes

0x20u16count ●placements

0x22..Placement[]placements ●16 bytes each

Reserved

1 field · 16 bytes

0x10u8[16]padding ◐padding and, in a few records, a leftover source filename such as LDF005G.3DL

16 bytes5 fields● 3 ◐ 1 ○ 1

0x00

Point at the bar to name a field; select it to jump to its row.

knownpartly knownunknown: investigatenamed, never setalways one valueunused bits

Position

3 fields · 6 bytes

0x00u16slot ●index into object_ids

0x04i16x ●always a multiple of 1000

0x06i16z ●always a multiple of 1000

Unknown

1 field · 2 bytes

0x02u16unknown_02 ○0, 0xffff or 0xfffe; undecoded

Reserved

1 field · 8 bytes

0x08u8[8]reserved_08 ◐zero on disk

Still to investigate

Every field marked unknown or partial above, and every bit that is set without a name or named without ever being set.

unknown_10○packed small byte pair; undecoded PolygonRecord
unknown_12○packed small byte pair; undecoded PolygonRecord
unknown_18○0 on 92% of faces; undecoded PolygonRecord
unknown_02○0, 0xffff or 0xfffe; undecoded Placement

/* Fight 3D Resources (FGT/). All fields little-endian unless the type says otherwise.

* Each comment gives status (● known ◐ partial ○ unknown), values seen, and meaning. */

/* ObjectHeader */

struct ObjectHeader {

/*00*/chartag[4];// ● Literal 3DOB (0x424f4433).

/*04*/uint16_tvertex_offset;// ● byte offset of the vertex table

/*06*/uint16_tslot_offset;// ● byte offset of the runtime vertex slots; equals trailing_offset on the 410 objects that have no parts

/*08*/uint16_tface_offset;// ● byte offset of the face-normal table

/*0a*/uint16_ttrailing_offset;// ● byte offset of the part table

/*0c*/uint16_treserved_0c[5];// ◐ 0 across the corpus

/*16*/uint16_tvertex_count_minus_one;// ● vertex count is this + 1

/*18*/uint16_tface_count_minus_one;// ● face count is this + 1

/*1a*/uint16_tpart_count;// ● first word of the 40-byte object lead; see [Moving parts](#moving-parts)

/*1c*/uint8_treserved_lead[38];// ◐ rest of the object lead; 0 across the corpus

}; /* 66 bytes */

/* Vertex */

struct Vertex {

/*00*/int16_tx;// ● model space

/*02*/int16_ty;// ● **+Y is down**, so up is -Y

/*04*/int16_tz;// ● model space

}; /* 6 bytes */

/* FaceNormal */

struct FaceNormal {

/*00*/int16_tx;// ● one per polygon; a **unit normal** in 14-bit fixed point (16384 = 1.0)

/*02*/int16_ty;// ● as x

/*04*/int16_tz;// ● as x

}; /* 6 bytes */

/* PolygonRecord */

struct PolygonRecord {

/*00*/uint16_trecord_size;// ● total bytes of this record; also 26 + 2*vertex_count - the fixed fields run +0x00..+0x19, then one word per vertex.

/*02*/uint16_tfirst_vertex_ptr;// ● equals the first entry of vertex_ptrs

/*04*/uint8_treserved_04[8];// ◐ zero on disk

/*0c*/uint16_tvertex_count_minus_one;// ● polygon has this + 1 vertices

/*0e*/uint16_tshade;// ● 0, 32, 64, 96, 128, 160 - the polygon's colour: a base index into the fight palette, see [Colour](#colour)

/*10*/uint16_tunknown_10;// ○ packed small byte pair; undecoded

/*12*/uint16_tunknown_12;// ○ packed small byte pair; undecoded

/*14*/int16_tbias;// ● -8..+8, the polygon's baked shade step, see [Colour](#colour)

/*16*/uint16_treserved_16;// ◐ 0 across the corpus

/*18*/uint16_tunknown_18;// ○ 0 on 92% of faces; undecoded

/*..*/uint16_tvertex_ptrs[vertex_count];// ● tailthe last vertex_count words

};

/* PartRecord */

struct PartRecord {

/*00*/uint16_tpolygon_ptr;// ● file offset of the part's first polygon record

/*02*/uint16_tpolygon_count_minus_one;// ● the part owns this + 1 consecutive polygons

/*04*/uint16_tvertex_list_ptr;// ● file offset of the part's vertex-index list

/*06*/uint16_tvertex_count_minus_one;// ● the list holds this + 1 entries

/*08*/int16_tpivot_x;// ● the axis the part turns about, in model space

/*0a*/int16_tpivot_y;// ● up is -Y, as everywhere else in the format

/*0c*/int16_tpivot_z;// ●

/*0e*/int16_ttranslation[3];// ● 0 on disk; runtime X/Y/Z translation added after pivot rotation

/*14*/int16_tangles[3];// ● runtime X/Y/Z angles; applied in Z, X, Y order; 0 on disk.

/*1a*/uint8_treserved_1a[6];// ◐ 0 on disk; runtime role unresolved

}; /* 32 bytes */

/* LandRecord */

struct LandRecord {

/*00*/chartag[4];// ● Literal 3DLD.

/*04*/uint16_tobject_ids[6];// ● ids of the LAND objects this record may place; 0xffff/0xfffe mark unused slots

/*10*/uint8_tpadding[16];// ◐ padding and, in a few records, a leftover source filename such as LDF005G.3DL

/*20*/uint16_tcount;// ● placements

/*..*/uint8_tplacements[];// ● 0x22..16 bytes each

};

/* Placement */

struct Placement {

/*00*/uint16_tslot;// ● index into object_ids

/*02*/uint16_tunknown_02;// ○ 0, 0xffff or 0xfffe; undecoded

/*04*/int16_tx;// ● always a multiple of 1000

/*06*/int16_tz;// ● always a multiple of 1000

/*08*/uint8_treserved_08[8];// ◐ zero on disk

}; /* 16 bytes */

Fight 3D resources

Archives

Object layout

Tables

Counts

Reserved

Position

Normal

Layout

Vertices

Colour

Reserved

Unknown

Geometry

Pivot

Runtime

Reserved

Objects

Placements

Reserved

Position

Unknown

Reserved

Still to investigate