ANIM (File Format)

This file format is almost completely documented Having trouble with bone rotations +/- 180 degrees in format 2

The ANIM format is used in conjunction with the CINF and CSKR to animate rigged CMDL meshes.

There are two versions of the ANIM format in Metroid Prime (indicated by the file's first long value):

Version	Description
0x0	Quaternion array format
0x2	Rotation vector bitstream format

Quaternion Array Format

The Quaternion Array Format (0x0) is a less common animation format in Metroid Prime. It's only used in a Ridley intro animation and the rotating pirate data artifact hologram above the Impact Crater.

The format maps animation channels to bones and supplies rotations as an array of quaternion (WXYZ) keys. Optionally, translations may be specified for a subset of bones as an array of float3 keys.

Data Type	Element Count	Identifier	Notes
Header0	1	header
char	header‑>bone_entry_count	bone_entry_map	The index-positions of this table correspond to the bone ids in the associated CINF. The value is 0xff if the bone is not animated by this ANIM or an index relating the bone_translation_map and quaternion_key_array below
long	1	bone_channel_count	Count of bone channels present in the bone_translation_map and quaternion_key_array below
char	bone_channel_count	bone_translation_map	Each bone channel may be optionally augmented with translation vectors at the bottom of the file
long	1	quaternion_key_count	Count of elements quaternion_key_array below
float4	quaternion_key_count	quaternion_key_array	The quaternion keys are interleaved like such (bone-major): |------------|------------|-----|------------| | bone0/key0 | bone0/key1 | ... | bone0/keyN | | bone1/key0 | bone1/key1 | ... | bone1/keyN | | .......... | .......... | ... | .......... | | boneN/key0 | boneN/key1 | ... | boneN/keyN | |------------|------------|-----|------------|
long	1	translation_key_count	Count of elements translation_key_array below
float3	translation_key_count	translation_key_array	The translation keys are interleaved like such (bone-major): |------------|------------|-----|------------| | bone0/key0 | bone0/key1 | ... | bone0/keyN | | bone1/key0 | bone1/key1 | ... | bone1/keyN | | .......... | .......... | ... | .......... | | boneN/key0 | boneN/key1 | ... | boneN/keyN | |------------|------------|-----|------------|
long	1	evnt_ref	ID for this ANIM's EVNT resource, or 0xffffffff if no events triggered

Header0

Offset	Length	Data Type	Description	Notes
0x0	4	float	duration	Time in seconds that the animation plays for
0x4	4	float	key_interval	Time in seconds between keys of each bone channel (reciprocal of frame-rate)
0x8	4	long	bone_entry_count	Count of bone-channels in animation
0xC	4	long	key_count	Count of keys for each bone channel (keys are set for every frame of the animation)