DKRDS Interactor (File Format)

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DKRDS Interactor is the nameless file format used in Diddy Kong Racing DS that stores a model's bone hierarchy and indexed keyframe poses for each bone. Bones defined here are referenced by ID from a corresponding DKRDS Model file's vertex data. Its type identifier in assets.bin is 0x2E.

File Format

The file byte order is always little endian.

Header

The file starts with a header that is 68 bytes long.

Offset	Type	Description
0x00	UInt16	Mode flags. AXXX XXXX XXXX XXBB: A: Identity scale. When set, the scale channel is skipped and every bone's scale is set to 1. B: Decode mode. Unknown exact usage. The format described here is documented from files that use mode 2.
0x02	UInt16	Unknown.
0x04	Int32	Unknown.
0x08	Int32	Unknown.
0x0C	Int32	Number of bones (B).
0x10	Int32	Skeleton Tree offset.
0x14	Int32	Unknown. Number of bones again?
0x18	Int32	Unknown.
0x1C	Int32	Number of frames (F).
0x20	Int32	Unknown. Affects interpolation between frames?
0x24	Int32	Axis Data offset.
0x28	UInt16	Bits per frame (I). Total size in bits of one frame's worth of keyframe index data across all bones (B * (PIW + RIW + SIW)).
0x2A	UInt16	Position Value Width (PVW) in bits per component.
0x2C	UInt16	Position Index Width (PIW) in bits.
0x2E	UInt16	Rotation Value Width (PVW) in bits per component.
0x30	UInt16	Rotation Index Width (RIW) in bits.
0x32	UInt16	Scale Value Width (SVW) in bits per component.
0x34	UInt16	Scale Index Width (SIW) in bits.
0x36	UInt16	Unknown. Maybe padding?
0x38	Int32	Position Value Stream offset (PVO), relative to the Axis Data section.
0x3C	Int32	Rotation Value Stream offset (RVO), relative to the Axis Data section.
0x40	Int32	Scale Value Stream offset (SVO), relative to the Axis Data section.
0x44	End of header

Skeleton Tree

This section defines the hierarchy of the bones, and it's always 2 * (B + 1) in length. The first entry corresponds to a default root bone and its parent index is always 0xFFFF (no parent).

Offset	Type	Description
0x00	UInt16[B + 1]	Parent bone indices for each bone.

Axis Data

This entire section defines up to three channels (position, rotation and scale), each with its own index bit width and value bit width.

Offset	Size	Description
0x00	Ceiling(I * F / 32) * 4	Index Bitstream. For frame F, the bit cursor starts at I * F. Then for each bone in order, read unsigned bits for its keyframe indices in the order PIW + RIW + SIW (this last one skipped if identity scale mode is set in the header). Bits are packed with no padding between bones or channels, and multiple bones can share the same index. The end position is aligned by 4.
0x00 + PVO	Variable	Position Value Stream. A sequence of XYZ signed entries (PVW bits per component). Entry K starts at bit offset K * 3 * PVW within this stream. Same coordinate scale as DKRDS Model's vertex positions.
0x00 + RVO	Variable	Rotation Value Stream. Same layout as the Position Value Stream, using RVW instead of PVW. A full rotation equals 2^RVW; each component is a plain signed angle in units of 1/2^RVW of a full rotation.
0x00 + SVO	Variable	Scale Value Stream. Same layout as the two previous streams. Final values are divided by 4096. Not present when identity scale mode is set in the header.

Tools

The following tools can handle DKRDS Interactor:

• (none)