Kingdom Hearts II - COCT

COCT is a set of data to realize collision detection. The targets are player (also NPC) and map mesh model.

COCT file structure

CollisionMeshGroup: (Has: BBox, Links to sub CollisionMeshGroup)
CollisionMesh: (Has: BBox, Unk1, Unk2)
Collision: (Has: Unk1)
Vertex: Single triangle or quad represents shape of Collision
Plane: xyzd
BBox: minXYZ, maxXYZ
SurfaceFlags: uint32

.
└── CollisionMeshGroup (Has one or more CollisionMesh)
    └── CollisionMesh (Has one or more Collision)
        └── Collision (3 or 4 Vertex. One Plane. 0 or 1 BBox. One SurfaceFlags)
            ├── Vertex
            ├── Plane
            ├── BBox
            └── SurfaceFlags

Note: BBox is short for bounding-box.

Here is association of table number and named tables:

Table1: CollisionMeshGroup
Table2: CollisionMesh
Table3: Collision
Table4: Vertex
Table5: Plane
Table6: BBox
Table7: SurfaceFlags

File header

Offset	Variable Type	Description
0	char[4]	The identifier of the file (Should be always 0x54434F43)
4	uint32_t	Version: always 1
8	uint32_t	Unknown
12	uint32_t	Unknown
16	uint32_t	Offset Header: always 0
20	uint32_t	Length Header: always 0x50
24	uint32_t	Offset Table1
28	uint32_t	Length Table1
32	uint32_t	Offset Table2
36	uint32_t	Length Table2
40	uint32_t	Offset Table3
44	uint32_t	Length Table3
48	uint32_t	Offset Table4
52	uint32_t	Length Table4
56	uint32_t	Offset Table5
60	uint32_t	Length Table5
64	uint32_t	Offset Table6
68	uint32_t	Length Table6
72	uint32_t	Offset Table7
76	uint32_t	Length Table7

CollisionMeshGroup (Table1)

Offset	Variable Type	Description
0	int16_t	Child1
2	int16_t	Child2
4	int16_t	Child3
6	int16_t	Child4
8	int16_t	Child5
10	int16_t	Child6
12	int16_t	Child7
14	int16_t	Child8
16	int16_t	MinX
18	int16_t	MinY
20	int16_t	MinZ
22	int16_t	MaxX
24	int16_t	MaxY
26	int16_t	MaxZ
28	uint16_t	First index to CollisionMesh (Table2)
30	uint16_t	Last index to CollisionMesh (Table2)

Notes:

• ChildX: -1 to mean nothing to point.
• (X,Y,Z) are inverted (-X,-Y,-Z).

CollisionMesh (Table2)

Offset	Variable Type	Description
0	int16_t	MinX
2	int16_t	MinY
4	int16_t	MinZ
6	int16_t	MaxX
8	int16_t	MaxY
10	int16_t	MaxZ
12	uint16_t	First index to Collision (Table3)
14	uint16_t	Last index to Collision (Table3)
16	uint16_t	Unknown
18	uint16_t	Unknown

Note: (X,Y,Z) are inverted (-X,-Y,-Z).

Collision (Table3)

Offset	Variable Type	Description
0	int16_t	Unknown
2	int16_t	Vertex1
4	int16_t	Vertex2
6	int16_t	Vertex3
8	int16_t	Vertex4: can be -1 in case of triangle
10	int16_t	Index to Plane (Table5)
12	int16_t	Index to BBox (Table6), otherwise use -1 is to apply Table2’s BBox
14	uint16_t	Index to SurfaceFlags (Table7)

Notes:

• Vertex1,2,3 composes one triangle.
• Vertex1,2,3,4 composes one triangle fan (usually its shape is quadrangle).

Vertex

Offset	Variable Type	Description
0	float	X
4	float	Y
8	float	Z
12	float	W: always 1

Note: (X,Y,Z) are inverted (-X,-Y,-Z).

Plane

Offset	Variable Type	Description
0	float	X
4	float	Y
8	float	Z
12	float	D

Note: (X,Y,Z,D) are inverted (-X,-Y,-Z,-D).

BBox

Offset	Variable Type	Description
0	int16_t	MinX
2	int16_t	MinY
4	int16_t	MinZ
6	int16_t	MaxX
8	int16_t	MaxY
10	int16_t	MaxZ

Note: (X,Y,Z) are inverted (-X,-Y,-Z).

SurfaceFlags

Offset	Variable Type	Description
0	uint32_t	Surface Flags

Bit fields:

Bit	Working	Description
0	partyStand
1	entityFallOverride
2	unkFallFlag1	seems to only affect the player
3	unkFallFlag2
4	partyCollide
5	objectCollide	affects enemies and field objects like the skateboard
6	unk01_1
7	attackCollide
8	unk02_1
9	unk02_2
10	ledgeGrab
11	dispBarrier
12	dispMessage
13	unk02_3
14	unk02_4
15	unk02_5
16	unk03_1
17	unk03_2
18	unk03_3
19	unk03_4
20	unk03_5
21	unk03_6
22	unk03_7
23	unk03_8
24	unk04_1
25	unk04_2
26	unk04_3
27	unk04_4
28	unk04_5
29	unk04_6
30	unk04_7
31	unk04_8