ANCS (File Format)

The ANCS format defines characters for animation in Metroid Prime 1 and 2. Starting in Metroid Prime 3, it was replaced by the CHAR format. The extension stands for ANimation Character Set.

This file format needs a lot of research Most of the file structure is known, but we still don't know what any of it actually is! Also, the table at the end of the file is unknown.

Root Structure

Data Type	Description	Notes
u16	Version	Always 1
CharacterSet	Character Set	Contains multiple CharacterInfo Entries
AnimationSet	Animation Set	Describes Meta Animations, Meta Transitions, Half Transitions, and Resource association

CharacterSet

Data Type	Element Count	Description	Notes
u16	1	Version	Always 1
u32	1	CharacterInfo count	Number of characters in this set.
CharacterInfo	character_info_count	Characters

CharacterInfo

Data Type	Element Count	Description	Notes
u32	1	id	Used by the engine to as a unique identifier within the Character Set.
u16	1	Info Type Count	Informs the engine which info types are present within the CharacterSet
string	1	Character Name	Human readable name, useful for editors, the engine does not use this internally.
CMDL	1	Character Model
CSKR	1	Character Skin
CINF	1	Character Rig
u32	1	Animation Count	Animations in AnimationSet that specifically relate to this character, some characters make heavy use of this abstraction, Space Pirates being the biggest culprit.
AnimationName	animation_count	Animation Names	Animations linked to this character by name and index.
PASDatabase	1	Parameterized Animation State Data	Not much is known about how this data is used.
ParticleResData	1	Particle systems used by this character
u32	1	Unknown
u32	1	Unknown	Not present when info_type_count <= 9
u32	1	Unknown	Not present when info_type_count <= 9
u32	1	Animation AABB count	Only present when info_type_count > 1
AnimationAABB	animation_aabb_count	Animation bounds	Only present when info_type_count > 1
u32	1	Effect Count	Only present when info_type_count > 1
Effect	effect_count	Effects used by this character, including which bones they're attached to	Only present when info_type_count > 1
CMDL	1	Overlay Model for status effects, such as ice when frozen	Only present when info_type_count > 3
CSKR	1	Overlay Skin for status effects, such as ice when frozen	Only present when info_type_count > 3
u32	1	Animation Index Count	The total number of animations used by this, only present when info_type_count > 4
u32	animation_index_count	Indices of each animation used by this character	Only present when info_type_count > 4
u32	1	Unknown	Only present when info_type_count > 9
u8	1	Unknown	Only present when info_type_count > 9
u32	1	Animation AABB Indexed Count	Only present when info_type_count > 9
AnimationAABB	animation_aabb_indexed_count	Animation bounds, referenced by index	Only present when info_type_count > 9

AnimationName

Data Type	Element Count	Description	Notes
u32	1	Index	The index into AnimationSet's MetaAnimation table.
string	1	Unknown	Not present when info_type_count >= 10
string	1	Animation Name	The name of the index ref'd Animation

ParticleResData

Data Type	Element Count	Description	Notes
u32	1	PART count	How many particle systems are used by this character
PART	part_count	The particle systems used by this character
u32	1	SWHC count	How many swooshes are used by this character
SWHC	swhc_count	The swooshes used by this character
u32	1	Unknown Count	How many unknown systems are used by this character
UniqueID32	unknown_count	The unknown systems used by this character
u32	1	ELSC count	How many electric systems are used by this character, only present if info_type_count > 5
ELSC	else_count	The electric systems used by this character	Only present if info_type_count > 5

AnimationAABB

Data Type	Description
string	Name
CAABox	Animation bounds

Effect

Data Type	Element Count	Description
string	1	Name
u32	1	Component Count
EffectComponent	component_count	Effect Components

EffectComponent

Data Type	Description
string	Name
FourCC	Type
UniqueID32	Resource as defined by Type
string	Bone to attach the effect to
float	Unknown
u32	Unknown
u32	Unknown

AnimationAABB Indexed

The only difference between this and the previous AnimationAABB is the fact that animations are referenced by index, rather than by name.

AnimationSet

Data Type	Element Count	Description	Notes
u16	1	Info Count	Enumeration of the presence of certain sections
u32	1	Animation Count	How many animations there are in the set
Animation	animation_count	Animations that can be referenced by characters
u32	1	Transition Count	How many transitions there are in the set
Transition	transition_count	Transitions that can be referenced by characters
MetaTransition	1	Default Transition
u32	1	Additive Animation Count	How many additive animations there are
AdditiveAnimation	additive_animation_count	Additive animations that can be referenced in some fashion	Reference method is currently unknown, presumably PASDatabase.
float	1	Time A	Unknown
float	1	Time B	Unknown
u32	1	Half Transition Count	How many half transitions there in the set, Only present if info_count > 2
HalfTransition	half_transition_Count	Half Transitions	Only present if info_count > 2
u32	1	Animation Resource Count	Only present if info_count > 3, and not present at all in MP2
AnimationResource	animation_resource_count	Animation Resources	Only present if info_count > 3, and not present at all in MP2
u32	1	Event Count	Only present in MP2
EVNT	event_count	Animation Events	Only present in MP2

Animation

Data Type	Description
string	Name
MetaAnimation	Animation configuration

MetaAnimation

MetaAnimations can be one of five types, and may contain children.

Data Type	Description
EMetaAnimationType	The Animation type
Primitive, Blend, PhaseBlend, Random or Sequence	The animation description, including name, animation ID, and index used to connect character animations references to actual animations.

EMetaAnimationType

Name	Value
Primitive	0
Blend	1
PhaseBlend	2
Random	3
Sequence	4

Primitive

Data Type	Description	Notes
ANIM	Animation ID	The asset ID for this particular animation
u32	Index	The ID used by characters to reference this animation
string	Name	The animations name
float	Unknown
u32	Unknown

Blend

Blend's structure is shared between Blend and PhaseBlend, with the only currently known difference being the animation type value.

Data Type	Description	Notes
MetaAnimation	Animation A	The animation to, presumably, blend from
MetaAnimation	Animation B	The animation to, presumably, blend to
float	Unknown
bool	Unknown

Random

Random may contain one or more children in an Animation -> Probability pair following this structure:

Data Type	Element Count	Description	Notes
u32	1	Animation Count	The number of child animations
AnimProbabilityPair	animation_count	The animations to select from	The exact manner these are used is currently unknown

AnimProbabilityPair

Data Type	Description	Notes
MetaAnimation	The animation use if the probability factor is met
u32	Probability	How probability is used is not currently known

Sequence

Sequence is a fairly easy to understand type, it simply plays a list of animations in succession as each animation finishes

Data Type	Element Count	Description
u32	1	Animation Count
MetaAnimation	animation_count	The animations to play in a sequence

Transition

Data Type	Description	Notes
u32	Animation Index A	The animation to transition from
u32	Animation Index B	The animation to transition to
MetaTransition	Transition configuration	Describes how the transition is performed

MetaTransition

Meta Transitions can be one of four types, and may contain animations.

Data Type	Description
EMetaTransitionType	The type of transition
TransAnimation, TransTransition, TransPhaseTransition, TransNoTransition	The transition configuration

EMetaTransitionType

Name	Value
TransAnimation	0
TransTransition	1
TransPhaseTransition	2
TransNoTransition	3

TransAnimation

Data Type	Description
MetaAnimation	The animation to use while transitioning

TransTransition

Data Type	Description
float	Time
u32	Unknown
bool	Unknown
bool	Unknown
u32	Unknown

AdditiveAnimation

Additive animations simply reference an existing animation within the above animation table, and has two unknown floats.

Data Type	Description
u32	Animation Index
float	Unknown
float	Unknown

Half Transition

A half transition is very similar to a regular transition, but has less configuration information, any other differences are currently unknown

Data Type	Description
u32	Animation Index
MetaTransition	Transition configuration.

AnimationResource

Data Type	Description
ANIM	Animation Asset ID
EVNT	Event Asset ID