FSKA (File Format)

Under Construction

This article is not finished. Help improve it by adding accurate information or correcting grammar and spelling.

The FSKA subfile stores animations which control how to transform bones of a model over time. It appears as a subfile of a BFRES file in the 2:nd index group. Unless otherwise noted, all offsets in the file are relative to themselves.

Header (FSKA)

An FSKA file begins with an 0x24 byte header that starts with the file identifier, followed by info about the image.

Offset	Type	Description
0x00	String	File magic. Always FSKA in ASCII.
0x04	Int32	Filename offset. The name of this file.
0x08	Int32	End of String table offset.
0x0C	UInt32	Unknown (possibly flags, as in other subfiles).
if BFRES version >= 3.4.0
0x10	UInt32	Frame count.
0x14	UInt16	Bone count.
0x16	UInt16	Unknown, possibly padding.
else
0x10	UInt16	Frame count.
0x12	UInt16	Bone count.
0x14	UInt32	Unknown, possibly padding.
0x18	UInt32	Unknown.
0x1C	UInt32	Unknown.
0x20	Int32	Bone array offset.

After this follows something like a UInt16 array of unknown length (around 38 to 42 elements), each mostly having values 0x0000 or 0xFFFF. It might be possible the first ones are an offset to user data like in other subfile formats.

Bone

This section describes how a bone of the model has to be transformed over time. It appears in an array of bones following and referenced by the header.

Offset	Type	Description
0x00	UInt32	Unknown.
0x04	Int32	Bone name offset of the bone to be transformed.
0x08	UInt16	Unknown.
0x0A	Byte	Track count. Might be 0 if the bone is not changed at all.
0x0B	Byte	Unknown, possibly padding.
0x0C	UInt32	Unknown.
0x10	Int32	Track array offset.
0x14	Int32	Base transform structure offset.

Base Transform

This structure stores how a bone is transformed in its initial state, and is referenced by each Bone section once.

Offset	Type	Description
0x00	Single[3]	Scale Vector 3 floats. The amount to scale the bone by.
0x0C	Single[4]	Rotation Vector, normally stored as euler rotation (X, Y, Z in radians) but it can be stored as a quaternion. The last float is not used by euler rotation and is therefore set to 1f.
0x1C	Single[3]	Translation Vector 3 floats. The amount to translate the bone by.

Track

This section controls how a specific transformation is applied on a bone over time. Tracks are referenced in an array by the Bone section; there might be no tracks if the bone will not be animated.

Offset	Type	Description
0x00	UInt16	Data type of the key frames and key data array.
0x02	UInt16	Key count.
0x04	UInt32	Animation type. Value Description 0x04 X Scale 0x08 Y Scale 0x0C Z Scale 0x10 X Translate 0x14 Y Translate 0x18 Z Translate 0x20 X Rotate 0x24 Y Rotate 0x28 Z Rotate
0x08	UInt32	Unknown.
0x0C	Single	Number of frames the animation plays.
0x10	Single	Data value scale, a factor to scale the data values with.
0x14	Single	Data value init, an initial value to offset the data values with.
if BFRES version >= 3.4.0
0x18	Single	Unknown.
0x1C	Int32	Key frames array offset.
0x20	Int32	Key data array offset.
else
0x18	Int32	Key frames array offset.
0x1C	Int32	Key data array offset.

Key Frames

The key frame array is of length and element type given by the header:

Data Types	Key Frame Element Type
0x02, 0x05, 0x06, 0x09, 0x0A	UInt16 >> 5
else	Byte

The resulting values of the elements specify the frame at which the key with the same index in the key data array is placed.

Key Data

Each key in the key array consists of 4 unknown values of different type dependent upon the data type specified in the header:

Data Types	Key Data Element Type
0x02	Single
0x05	Int16
0x06	Int16
0x09, 0x0A	Byte

Tools

The following tools can handle FSKA files:

• ModelThingy, by Ploaj (can animate models)