HZC (File Format)

HZC is a collision format used in some Nintendo DS and Nintendo 3DS games developed by Firebrand Games such as Cartoon Network Racing DS and Race Driver: Create & Race.

File Format

The file byte order is always little endian.

Header

The file starts with the following header:

Offset	Type	Description
0x00	UInt16	Version number.
0x02	UInt16	Number of vertices (V).
0x04	UInt16	Number of triangles (T).
0x06	UInt16	Number of custom attributes (A).

Vertex Data

Followed by the header, there's plain vertex position data stored as a sequence of groups of 3 Int32s (one per axis). The values need to be divided by 4096.

Offset	Type	Description
0x00	Int32[3][V]	Vertex XYZ coordinates.

Triangle Index Data

After the vertex data, there's a list of T * 3 UInt16s that correspond to the indices of each triangle.

Offset	Type	Description
0x00	UInt16[3][T]	Triangle indices.

Triangle Normal Data

Directly after the triangle indices there are the triangle's face normals, consisting of 3 Int32s per triangle. They seem to match the cross product of the triangle's first two edges with a magnitude of 4096.

Offset	Type	Description
0x00	Int32[3][T]	Triangle XYZ normals.

Grid

Followed by the triangle normal data, there's a spatial grid consisting of 3D cells used for better collision detection. Each cell corresponds to an index to the Linked List Array.

Offset	Type	Description
0x00	Int32	Number of cells (C).
0x04	UInt16[C]	Cell indices. 0xFFFF if empty.

Grid Info

Offset	Type	Description
0x00	Int32[3]	Number of cells in the grid's XYZ dimensions.
0x0C	Int32[3]	Grid bounding box minimum XYZ position.
0x18	Int32[3]	Grid bounding box maximum XYZ position.
0x24	Int32	Unknown. Always 0?

Linked List Array

After the grid data there's an array of triangle/cell links.

Offset	Type	Description
0x00	Int32	Number of links (L).
0x04	UInt16[2][L]	Triangle index and next index. The next index is 0xFFFF at the end of a cell's chain, otherwise another index into this same array.

Custom Attribute Table

This section is only present if A > 0. It contains a list of T UInt16s that link each triangle to a Key-Value Property in a string table. Some tracks contain unused attributes.

Offset	Type	Description
0x00	UInt16[T]	Attribute IDs. 0xFFFF if none.

String Table

Offset	Type	Description
0x00	Key-Value Property[A]	Key-value property strings.

Key-Value Property

Offset	Type	Description
0x00	UInt16	Key string length (PK).
0x02	String (Char[PK])	Attribute key.
0x02 + K	UInt16	Value string length (PV).
0x04 + K	String (Char[PV])	Attribute value. Always float(SurfaceType)=X.000000 in Cartoon Network Racing DS.

Seen attributes (Cartoon Network Racing DS)

Key	Value	Found in
COL_grass	float(SurfaceType)=1.000000	CrossTown.hzc evilGlade.hzc IslandDash.hzc
grass	float(SurfaceType)=1.000000	Townsville.hzc
Grass	float(SurfaceType)=1.000000	AronSpeed.hzc MandarkLab.hzc MidNowhere.hzc
heavyTerrain	float(SurfaceType)=2.000000	CrossTown.hzc MandarkLab.hzc SnowSunday.hzc
HeavyTerrain	float(SurfaceType)=3.000000	IslandDash.hzc MandarkLab.hzc
MudPuddle	float(SurfaceType)=5.000000	IslandDash.hzc
not_track	float(SurfaceType)=1.000000 float(SurfaceType)=4.000000	MandarkLab.hzc MidNowhere.hzc Townsville.hzc
raceTrackFloor	—	DextersLab.hzc
raceTrackWalls	—	DextersLab.hzc
RoughGround	float(SurfaceType)=0.000000 float(SurfaceType)=4.000000	AronSpeed.hzc MandarkLab.hzc MidNowhere.hzc
terrainLight	float(SurfaceType)=0.000000	MandarkLab.hzc MountRush.hzc

Version List

Version	Found in
1.3	Cartoon Network Racing DS Ferrari Challenge: Trofeo Pirelli DS
1.4	Race Driver: Create & Race
1.5	Cars 2: The Video Game DS Colin McRae: Dirt 2 DS Hot Wheels: Track Attack DS Need for Speed: Nitro DS Need for Speed: Nitro-X Need for Speed: Undercover DS Race Driver: Grid DS SpongeBob's Boating Bash
1.12	Planet 51: The Game DS TrackMania DS
1.14	TrackMania Turbo (2010)
1.18	Cars 2: The Video Game 3DS NASCAR Unleashed
1.19	Need for Speed: The Run 3DS
1.22	Fast & Furious: Showdown 3DS
1.23	Hot Wheels: World's Best Driver 3DS WRC FIA World Rally Championship 3DS

Tools

The following tools can handle HZC files:

• (none)