DKRDS Track (File Format)

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DKRDS Track is the nameless file format used in Diddy Kong Racing DS that stores the tracks' section models, collision and textures. Its type identifier in assets.bin is 0x9A.

File Format

The file byte order is always little endian.

Header

The file starts with a header that is 56 bytes long.

Offset	Type	Description
0x00	Int32	Number of sections (N).
0x04	Int32	Track Section Group offset.
0x08	Int32	Collision Effects offset.
0x0C	Byte[4]	Unknown. Always 0xCCCCCCCC.
0x10	Int32	Culling Groups offset.
0x14	Int32	Culling Groups data type: 1 = 4-byte per N group. 2 = 8-byte per N group.
0x18	Int32	Number of textures (X).
0x1C	Int32	Texture Group offset.
0x20	Int32	Unknown Section 1 offset.
0x24	Int32	Wish Race Unknown Section entry count.
0x28	Int32	Wish Race Unknown Section offset.
0x2C	Byte[4]	Unknown. Seems to be some kind of flags.
0x30	Int32	Unknown.
0x34	Int32	File size.
0x38	End of header

Track Section Group

This group starts with a list of N offsets.

Track Section Header

Offset	Type	Description
0x00	Int32[N]	Track Section Entry offsets. Relative to the start of this group.

Track Section Entry

Every section entry defines model and collision data. The entry starts with a 32-byte header.

Track Section Entry Header

Offset	Type	Description
0x00	Byte	Unknown.
0x01	Byte	Unknown. Always 5?
0x02	UInt16	Unknown.
0x04	UInt16	Number of polygon groups (P).
0x06	UInt16	Number of vertices in Track Section Vertex Data (V).
0x08	UInt16	Number of UVs in Track Section UV Data (U).
0x0A	UInt16	Number of colors in Track Section Color Data (C).
0x0C	Int32	Track Section Triangle Data offset.
0x10	Int32	Track Section Collision Data offset.
0x14	Int32	Track Section Vertex Data offset.
0x18	Int32	Track Section UV Data offset.
0x1C	Int32	Track Section Color Data offset.
0x20	End of header, start of Track Section Data

Track Section Data

This data follows directly after the header of the section entry and starts with a 76-byte header.

Offset	Type	Description
0x00	Int32	Unknown. Seems to be always 0xFFFFFFFF and set to an address when loaded in memory.
0x04	Int32[3]	Collision XYZ offset.
0x10	Int32[3]	Visual model XYZ offset. The units are not the same as the collision offset.
0x1C	Track Section AABB[2]	AABB areas of the entire section used for collision detection. The second AABB always seems to be a duplicate of the first.
0x4C	End of header, start of Track Section Polygon Data

Track Section AABB

Track sections contain 2 identical AABB areas each. It is unknown why there's a duplicate, perhaps used during runtime after object space transform. All values need to be divided by 64 in order to obtain the absolute position data and match with the visual models.

Offset	Type	Description
0x00	Int32[3]	AABB minimum XYZ position.
0x0C	Int32[3]	AABB XYZ extent.

Track Section Polygon Data

This section seems to store P polygon groups' attributes.

Offset	Type	Description
0x00	Polygon Group Entry[P]	Polygon group entries.

Polygon Group Entry

Each polygon group entry is 12 bytes long.

Offset	Type	Description
0x00	UInt16	First triangle ID.
0x02	UInt16	Number of triangles.
0x04	Byte	Main collision attribute. AAAA BBBB: A: Shadow level. The higher the value, the darker the character gets. B: Collision flag: ID Description 0x01 Road and effects. 0x05 Wall. 0x08 Special effects? 0x0C Invisible wall.
0x05	Byte	Secondary collision attribute: Main flag = 0x01: ID Description 0x00 Special effect? Used for water. 0x01 Pass through/no effect. 0x04 Road. Main flag = 0x08: ID Description 0x01 Water.
0x06	UInt16	Tertiary collision attribute. Split in bits. Main flag = 0x01: ID Description 0x01 Unknown. Used in non-collideable stuff. 0x02 Water, inflates tires in car. 0x10 Unknown. Used in non-collideable stuff. 0x20 Unknown. Used in non-collideable stuff. Main flag = 0x0C: ID Description 0x04 Ignore when using plane.
0x08	Byte[4]	Unknown.

The number of triangles T can be calculated by adding the first triangle ID to the number of triangles of the last polygon group entry.

Track Section Triangle Data

This section stores T triangle entries.

Offset	Type	Description
0x00	Triangle Entry[T]	Triangle entries.

Triangle Entry

Each triangle entry is 20 bytes long.

Offset	Type	Description
0x00	UInt16	Attribute flags. AAAA AAAA AAAA AAAB: A: Texture ID. B: Is collidable.
0x02	UInt16[3]	Face XYZ normals. Values need to be divided by 4096.
0x08	Byte[4]	Vertex position indices. The index for each of the 3 vertices is 10 bits long. 2 last bits are unknown.
0x0C	Byte[4]	UV indices. The index for each of the 3 vertices is 10 bits long. 2 last bits are unknown.
0x10	Byte[4]	Color indices. The index for each of the 3 vertices is 10 bits long. 2 last bits are unknown.

Track Section Collision Data

4-byte data per triangle (?). TBD

Track Section Vertex Data

Vertex data is stored as 6-byte groups per entry V.

Offset	Type	Description
0x00	Int16[3][V]	Vertex XYZ position.

Track Section UV Data

UV data is stored as 4-byte groups per entry U.

Offset	Type	Description
0x00	Int16[2][U]	Vertex UV position.

Track Section Color Data

Color data is stored as 2-byte groups per entry C.

Offset	Type	Description
0x00	UInt16[C]	RGBA5551 color.

Collision Effects

Each texture is linked to 2 specific collision effects that affect the vehicle's speed, particles and lighting. This section contains 2 blocks of X UInt16s.

Offset	Type	Description
0x00	UInt16[X]	Effects, split in bits.
X * 2	UInt16[X]	Unknown. This seems to be a copy of the previous block?

Culling Groups

This section includes a 4-byte or 8-byte per track section values that determine which section models are loaded when entering a specific section. Each section is represented as 1 bit.

Offset	Type	Description
0x00	UInt16[N]/UInt32[N]	Culled model sections, represented as N bits, 1 per section, in order from the least to the most significant bit. 0 if culled, 1 if loaded.

Texture Group

See DKRDS Texture Group.

Unknown Section 1

TBD

Wish Race Unknown Section

This section is only used for the Wish Race tracks. TBD

Tools

The following tools can handle DKRDS Track:

• (none)