ANIM (Metroid Prime): Difference between revisions

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''This article is for the ANIM format used in ''Metroid Prime''. See [[ANIM (File Format)]] for the other revisions of this format.''
''This article is for the ANIM format used in ''Metroid Prime'' and ''Metroid Prime 2: Echoes''. See [[ANIM (File Format)]] for the other revisions of this format.''


The '''ANIM format''' is used in conjunction with [[CINF (Metroid Prime)|CINF]] + [[CSKR (Metroid Prime)|CSKR]]
The '''ANIM format''' is used in conjunction with [[CINF (File Format)|CINF]] + [[CSKR (File Format)|CSKR]] rigging to animate [[CMDL (Metroid Prime)|CMDL meshes]]. The format is largely the same between the two games, with the main difference being that starting in ''Metroid Prime 2'', support for animating scale was added.
rigging to animate [[CMDL (Metroid Prime)|CMDL meshes]].


There are two versions of the ANIM format in ''Metroid Prime'' (indicated by the file's first u32 value):
There are two versions of the ANIM format (indicated by the file's first u32 value), one with compressed animations and one with uncompressed ones:


{| class="wikitable"
{| class="wikitable"
Line 11: Line 10:
|-
|-
|0x0
|0x0
|[[#Quaternion Array Format|Quaternion Array Format]]
|[[#Quaternion Array Format (Uncompressed)|Quaternion Array Format (Uncompressed)]]
|-
|-
|0x2
|0x2
|[[#Rotation Vector Bitstream Format|Rotation Vector Bitstream Format]]
|[[#Rotation Vector Bitstream Format (Compressed)|Rotation Vector Bitstream Format (Compressed)]]
|}
|}


== Quaternion Array Format ==
== Quaternion Array Format (Uncompressed) ==


The '''Quaternion Array Format''' (0x0) is a less common animation format in ''Metroid Prime''.
The '''Quaternion Array Format''' (0x0) is a less common animation format. In ''Metroid Prime'', it only appears in a Ridley intro animation and the rotating pirate data artifact hologram above the Impact Crater, as well as some unused Samus animations, while in ''Metroid Prime 2'', it only seems to show up in some draft/test animations not used in the final game.
It only appears in a ''Ridley'' intro animation and the rotating ''pirate data'' artifact hologram
above the Impact Crater, as well as some unused Samus animations.


The format maps animation channels to bones and supplies rotations as an array of [[wikipedia:Quaternion|quaternion]] (WXYZ) keys.
This format stores uncompressed animations by mapping animation channels to bones, supplying rotations as an array of [[wikipedia:Quaternion|quaternion]] (WXYZ) keys and translations/scales as an array of XYZ keys. Translations may be specified for a subset of bones as an array of XYZ keys. In ''Metroid Prime'', rotation keys are required on every channel, while translations may be specified for a subset of bones. In ''Metroid Prime 2'', all three transform components are opt-in.  
Optionally, translations may be specified for a subset of bones as an array of float3 keys.  


=== Layout ===
=== Layout ===


{| class="wikitable"
{| class="wikitable"
!Data Type
!Offset
!Element Count
!Type
!Identifier
!style="width: 215px;"|Element Count
!style="width: 240px;"|Name
!Notes
!Notes
!MP1
!MP2
|-
|0x4
|[[Char Anim Time]]
|1
|'''Duration'''
|Time in seconds that the animation plays for
|{{check}}
|{{check}}
|-
|0xC
|[[Char Anim Time]]
|1
|'''Key Interval'''
|Time in seconds between keys of each bone channel (reciprocal of frame-rate)
|{{check}}
|{{check}}
|-
|0x14
|u32
|1
|'''Key Count'''
|Count of keys for each bone channel (keys are set for every frame of the animation)
|{{check}}
|{{check}}
|-
|0x18
|u32
|1
|'''Root Bone ID'''
|ID of the root bone in this ANIM
|{{check}}
|{{check}}
|-
|0x1C
|u32
|1
|'''Bone Channel Count'''
|Count of bone channel indices in the next array. Always 100.
|{{check}}
|{{check}}
|-
|0x20
|u8
|''Bone Channel Count''
|'''Bone Channel Index Array'''
|This table maps each bone to a bone channel, with the index-position corresponding to a ''Bone ID'' in the associated [[CINF (File Format)|CINF]], while the value corresponds to a bone channel index. The value is 0xFF if the bone is not animated by this ANIM.
|{{check}}
|{{check}}
|-
|-
|[[#Header0|Header0]]
|{{unknown|}}
|u32
|1
|1
|header
|'''Rotation Channel Index Count'''
|
|Count of rotation channel indices in the next array. Matches the number of valid bone channels.
|{{nocheck}}
|{{check}}
|-
|-
|{{unknown|}}
|u8
|u8
|header.bone_entry_count
|''Rotation Channel Index Count''
|bone_entry_map
|'''Rotation Channel Index Array'''
|The index-positions of this table correspond to the ''Bone IDs'' in the associated [[CINF (Metroid Prime)|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
|This table maps each bone channel to a rotation channel, with the index-position corresponding to an entry in the ''Bone Channel Index Array'' above (disregarding 0xFF entries), while the value corresponds to the index of a rotation channel. The value is 0xFF if the bone is not rotated by this ANIM. '''Note:''' In ''Metroid Prime'', every bone channel always has rotations, so this array is omitted.
|{{nocheck}}
|{{check}}
|-
|-
|{{unknown|}}
|u32
|u32
|1
|1
|bone_channel_count
|'''Translation Channel Index Count'''
|Count of bone channels present in the ''bone_translation_map'' and ''quaternion_key_array'' below
|Count of translation channel indices in the next array. Matches the number of valid bone channels.
|{{check}}
|{{check}}
|-
|-
|{{unknown|}}
|u8
|u8
|bone_channel_count
|''Translation Channel Index Count''
|bone_translation_map
|'''Translation Channel Index Array'''
|Each bone channel may be optionally augmented with translation vectors at the bottom of the file. The index-positions of this table correspond to the values in the ''bone_entry_map'' above. The value is 0xff if the bone is not translated by this ANIM or an index relating the ''quaternion_key_array'' below
|This table maps each bonechannel to a translation channel, with the index-position corresponding to an entry in the ''Bone Channel Index Array'' above (disregarding 0xFF entries), while the value corresponds to the index of a translation channel. The value is 0xFF if the bone is not translated by this ANIM.
|{{check}}
|{{check}}
|-
|-
|{{unknown|}}
|u32
|u32
|1
|1
|quaternion_key_count
|'''Scale Channel Index Count'''
|Count of elements in ''quaternion_key_array'' below
|Count of scale channel indices in the next array. Matches the number of valid bone channels.
|{{nocheck}}
|{{check}}
|-
|-
|float4
|{{unknown|}}
|quaternion_key_count
|u8
|quaternion_key_array
|''Scale Channel Index Count''
|The quaternion keys are interleaved as such (bone-major):
|'''Scale Channel Index Array'''
<pre>
|This table maps each bone channel to a scale channel, with the index-position corresponding to an entry in the ''Bone Channel Index Array'' above (disregarding 0xFF entries), while the value corresponds to the index of a scale channel. The value is 0xFF if the bone is not scaled by this ANIM.
|------------|------------|-----|------------|
|{{nocheck}}
| bone0/key0 | bone0/key1 | ... | bone0/keyN |
|{{check}}
| bone1/key0 | bone1/key1 | ... | bone1/keyN |
| .......... | .......... | ... | .......... |
| boneN/key0 | boneN/key1 | ... | boneN/keyN |
|------------|------------|-----|------------|
</pre>
|-
|-
|{{unknown|}}
|u32
|u32
|1
|1
|translation_key_count
|'''Scale Key Count'''
|Count of elements in ''translation_key_array'' below
|Count of elements in ''Scale Key Array'' below
|{{nocheck}}
|{{check}}
|-
|-
|{{unknown|}}
|float3
|float3
|translation_key_count
|''Scale Key Count''
|translation_key_array
|'''Scale Key Array'''
|The translation keys are interleaved as such (bone-major):
|The scale keys are interleaved as such (bone-major):
<pre>
<pre>
|------------|------------|-----|------------|
|------------|------------|-----|------------|
Line 89: Line 150:
|------------|------------|-----|------------|
|------------|------------|-----|------------|
</pre>
</pre>
Any bone channels that were marked 0xff in the ''bone_translation_map'' are skipped by this array
|{{nocheck}}
|{{check}}
|-
|-
|{{unknown|}}
|u32
|u32
|1
|1
|evnt_ref
|'''Rotation Key Count'''
|ID for this ANIM's [[EVNT (File Format)|EVNT]] resource, or 0xffffffff if no events triggered
|Count of elements in ''Rotation Key Array'' below
|}
|{{check}}
 
|{{check}}
=== Header0 ===
 
{| class="wikitable"
!Offset
!Length
!Data Type
!Identifier
!Notes
|-
|-
|0x0
|{{unknown|}}
|4
|float4
|float
|''Rotation Key Count''
|duration
|'''Rotation Key Array'''
|Time in seconds that the animation plays for
|The rotation keys are interleaved the same way as the scale keys. In ''Metroid Prime 2'', any bone channels that were marked 0xFF in the ''Rotation Channel Index Array'' are skipped.
|{{check}}
|{{check}}
|-
|-
|0x4
|{{unknown|}}
|4
|u32
|u32
|{{unknown|unknown1}}
|1
|
|'''Translation Key Count'''
|Count of elements in ''Translation Key Array'' below
|{{check}}
|{{check}}
|-
|-
|0x8
|{{unknown|}}
|4
|float3
|float
|''Translation Key Count''
|key_interval
|'''Translation Key Array'''
|Time in seconds between keys of each bone channel (reciprocal of frame-rate)
|The translation keys are interleaved the same way as the scale keys. Any bone channels that were marked 0xFF in the ''Translation Channel Index Array'' are skipped.
|{{check}}
|{{check}}
|-
|-
|0xC
|{{unknown|}}
|4
|[[EVNT (File Format)|EVNT]]
|u32
|1
|{{unknown|unknown2}}
|'''EVNT Ref'''
|
|ID for this ANIM's [[EVNT (File Format)|EVNT]] resource, or 0xFFFFFFFF if no events triggered
|-
|{{check}}
|0x10
|{{nocheck}}
|4
|u32
|key_count
|Count of keys for each bone channel (keys are set for every frame of the animation)
|-
|0x14
|4
|u32
|{{unknown|unknown3}}
|
|-
|0x18
|4
|u32
|bone_entry_count
|Count of bone-channels in animation
|}
|}


== Rotation Vector Bitstream Format ==
== Rotation Vector Bitstream Format (Compressed) ==


The '''Rotation Vector Bitstream Format''' (0x2) is the most widely used animation format in ''Metroid Prime''.
The '''Rotation Vector Bitstream Format''' (0x2) is the most widely used animation format.
The format uses a compressed [[wikipedia:Bitstream|bitstream]] to store keys that have been
The format uses a compressed [[wikipedia:Bitstream|bitstream]] to store keys that have been
[[wikipedia:Delta encoding|delta encoded]] and [[wikipedia:Quantization (signal processing)|quantized]]
[[wikipedia:Delta encoding|delta encoded]] and [[wikipedia:Quantization (signal processing)|quantized]]
Line 161: Line 206:


=== Key Values ===
=== Key Values ===
When decoding the animation, each bone's rotation (and possibly translation) values are initialized to the ''initial_*''
When decoding the animation, each bone's attribute values are initialized to the ''Initial *''
values in the ''bone channel descriptors''. For every frame of every bone channel, the key value in the bitstream is ''added''
values in the ''bone channel descriptors''. For every frame of every bone channel, the key value in the bitstream is ''added''
with the previous key value (to resolve the delta encoding).  
with the previous key value (to resolve the delta encoding).  


Once resolved, rotation components are divided by ''rotation_divisor'', resulting in an axis-angle
Once resolved, rotation components are divided by ''Rotation Divisor'', resulting in an axis-angle
[[wikipedia:Axis–angle_representation#Rotation_vector|rotation vector]]. This rotation vector is converted
[[wikipedia:Axis–angle_representation#Rotation_vector|rotation vector]]. This rotation vector is converted
to quaternion imaginary components with the W component derived via normalized-difference and a ''sign-bit''
to quaternion imaginary components with the W component derived via normalized-difference and a ''sign-bit''
Line 179: Line 224:
</pre>
</pre>


Translation components are multiplied by ''translation_multiplier'', yielding world units.
Translation components are multiplied by ''Translation Multiplier'', and scale components are multiplied by ''Scale Multiplier''.


=== Layout ===
=== Layout ===


{| class="wikitable"
{| class="wikitable"
!Data Type
!Type
!Element Count
!style="width: 220px;"|Element Count
!Identifier
!style="width: 240px;"|Name
!Notes
!Notes
!MP1
!MP2
|-
|-
|[[#Header2|Header2]]
|u32
|1
|1
|header
|'''Scratch Size'''
|
|Amount of memory that the animation system needs to allocate to process animation
|{{check}}
|{{check}}
|-
|-
|u32
|[[EVNT (File Format)|EVNT]]
|round_up(header.key_bitmap_length / 32)
|1
|key_bitmap
|'''EVNT Ref'''
|Word-packed bitmap. Each word is read from least-significant to most-significant bit. A set bit indicates the frame at the bit's position has keys for each bone channel.
|ID for this ANIM's [[EVNT (File Format)|EVNT]] resource, or 0xFFFFFFFF if no events triggered
|{{check}}
|{{nocheck}}
|-
|-
|u32
|u32
|1
|1
|bone_channel_count
|{{unknown|Unknown 1}}
|Count of animated bone channels (matches header.bone_channel_count)
|Always 0x1
|{{check}}
|{{nocheck}}
|-
|-
|u32
|u16
|1
|1
|bone_channel_count
|{{unknown|Unknown 2}}
|Duplicate channel count for some reason
|
|{{nocheck}}
|{{check}}
|-
|-
|[[#Bone Channel Descriptor|Bone Channel Descriptor]]
|float
|header.bone_channel_count
|1
|bone_channel_descriptor_table
|'''Duration'''
|Table describing animated bone channels
|Time in seconds that the animation plays for
|{{check}}
|{{check}}
|-
|-
|u32
|float
|<remainder of file>
|1
|key_bitstream
|'''Interval'''
|Word-packed bitstream laid out as described by the descriptor table. The bitstream is unpacked just like ''key_bitmap'' (least-significant to most-significant).
|Time in seconds between frames (reciprocal of frame-rate, typically 30-fps)
Key values are tightly-packed, quantized integers whose bit-depth is specified by the ''q_*'' values in the descriptor table.
|{{check}}
Each bone-channel key-set starts with a single bit providing the ''W sign-bit'' (1 for negative, 0 for positive).
|{{check}}
 
The key integers are signed using [[wikipedia:Two's complement|Two's complement]] representation.
|}
 
=== Header2 ===
 
{| class="wikitable"
!Offset
!Length
!Data Type
!Identifier
!Notes
|-
|-
|0x0
|4
|u32
|u32
|scratch_size
|1
|Amount of memory that the animation system needs to allocate to process animation
|'''Root Bone ID'''
|ID of the root bone in this ANIM
|{{check}}
|{{check}}
|-
|-
|0x4
|4
|u32
|u32
|evnt_ref
|1
|ID for this ANIM's [[EVNT (File Format)|EVNT]] resource, or 0xffffffff if no events triggered
|'''Looping Flag'''
|When non-zero, engine identifies this ANIM as looping
|{{check}}
|{{check}}
|-
|-
|0x8
|4
|u32
|u32
|{{unknown|unknown0}}
|1
|Always 0x1
|'''Rotation Divisor'''
|Rotation vectors are divided by this value before being applied
|{{check}}
|{{check}}
|-
|-
|0xC
|4
|float
|float
|duration
|1
|Time in seconds that the animation plays for
|'''Translation Multiplier'''
|Translation vectors are multiplied by this value before being applied
|{{check}}
|{{check}}
|-
|-
|0x10
|4
|float
|float
|interval
|1
|Time in seconds between frames (reciprocal of frame-rate, typically 30-fps)
|'''Scale Multiplier'''
|Scale vectors are multiplied by this value before being applied
|{{nocheck}}
|{{check}}
|-
|-
|0x14
|4
|u32
|u32
|{{unknown|unknown1}}
|1
|Always 0x3
|'''Bone Channel Count'''
|Count of bone channels present in ANIM
|{{check}}
|{{check}}
|-
|-
|0x18
|4
|u32
|u32
|{{unknown|unknown2}}
|1
|Always 0x0
|{{unknown|Unknown 4}}
|Always 0x1
|{{check}}
|{{check}}
|-
|-
|0x1C
|4
|u32
|u32
|rotation_divisor
|1
|Rotation vectors are divided by this value before being applied
|'''Key Bitmap Length'''
|Number of bits in ''Key Bitmap''
|{{check}}
|{{check}}
|-
|-
|0x20
|u32
|4
|round_up(''Key Bitmap Length'' / 32)
|float
|'''Key Bitmap'''
|translation_multiplier
|Word-packed bitmap. Each word is read from least-significant to most-significant bit. A set bit indicates the frame at the bit's position has keys for each bone channel. If the bit is unset, the keys must be generated via interpolation.
|Translation vectors are multiplied by this value before being applied
|{{check}}
|{{check}}
|-
|-
|0x24
|4
|u32
|u32
|bone_channel_count
|1
|Count of bone channels present in ANIM
|'''Bone Channel Count'''
|Count of animated bone channels (matches the previous bone channel count)
|{{check}}
|{{nocheck}}
|-
|-
|0x28
|4
|u32
|u32
|{{unknown|unknown3}}
|1
|Always 0x1
|'''Bone Channel Descriptor Count'''
|Count of bone channel descriptors in ''Bone Channel Descriptor Table''. Matches the ''Bone Channel Counts''.
|{{check}}
|{{check}}
|-
|[[#Bone Channel Descriptor|Bone Channel Descriptor]]
|''Bone Channel Descriptor Count''
|'''Bone Channel Descriptor Table'''
|Table describing animated bone channels
|{{check}}
|{{check}}
|-
|-
|0x2C
|4
|u32
|u32
|key_bitmap_length
|<remainder of file>
|Number of bits in ''key_bitmap''
|'''Key Bitstream'''
|Word-packed bitstream laid out as described by the descriptor table. The bitstream is unpacked just like ''Key Bitmap'' (least-significant to most-significant).
Key values are tightly-packed, quantized integers whose bit-depth is specified by the ''* Bits'' values in the descriptor table.
Each bone-channel key-set starts with a single bit providing the ''W sign-bit'' (1 for negative, 0 for positive).
 
The key integers are signed using [[wikipedia:Two's complement|Two's complement]] representation.
 
The keys are interleaved as such (key-major):
<pre>
|------------|------------|-----|------------|
| bone0/key0 | bone1/key0 | ... | boneN/key0 |
| bone0/key1 | bone1/key1 | ... | boneN/key1 |
| .......... | .......... | ... | .......... |
| bone0/keyN | bone1/keyN | ... | boneN/keyN |
|------------|------------|-----|------------|
</pre>
|{{check}}
|{{check}}
|}
|}


Line 310: Line 388:
{| class="wikitable"
{| class="wikitable"
!Offset
!Offset
!Length
!Type
!Data Type
!Name
!Identifier
!Notes
!Notes
!MP1
!MP2
|-
|-
|0x0
|0x0
|4
|u32
|u32
|bone_id
|'''Bone ID'''
|''Bone ID'' in the associated [[CINF (Metroid Prime)|CINF]] for this bone channel
|''Bone ID'' in the associated [[CINF (File Format)|CINF]] for this bone channel
|{{check}}
|{{check}}
|-
|-
|0x4
|0x4
|2
|u16
|u16
|key_count
|'''Rotation Key Count'''
|Number of keys in the bitstream for this bone channel (same value for all channels in animation)
|Number of rotation keys in the bitstream for this bone channel.
'''In MP2, if this value is 0, the remaining Rotation fields aren't present'''
|{{check}}
|{{check}}
|-
|-
|0x6
|0x6
|2
|s16
|s16
|initial_rx
|'''Initial Rotation X'''
|Initial X value of bone's rotation vector
|Initial X value of bone's rotation vector
|{{check}}
|{{check}}
|-
|-
|0x8
|0x8
|1
|u8
|u8
|q_rx
|'''Rotation Bits X'''
|Number of bits allocated to bone's ''rx'' in bitstream
|Number of bits allocated to bone's rotation delta X in bitstream
|{{check}}
|{{check}}
|-
|-
|0x9
|0x9
|2
|s16
|s16
|initial_ry
|'''Initial Rotation Y'''
|Initial Y value of bone's rotation vector
|Initial Y value of bone's rotation vector
|{{check}}
|{{check}}
|-
|-
|0xB
|0xB
|1
|u8
|u8
|q_ry
|'''Rotation Bits Y'''
|Number of bits allocated to bone's ''ry'' in bitstream
|Number of bits allocated to bone's rotation delta Y in bitstream
|{{check}}
|{{check}}
|-
|-
|0xC
|0xC
|2
|s16
|s16
|initial_rz
|'''Initial Rotation Z'''
|Initial Z value of bone's rotation vector
|Initial Z value of bone's rotation vector
|{{check}}
|{{check}}
|-
|-
|0xE
|0xE
|1
|u8
|u8
|q_rz
|'''Rotation Bits Z'''
|Number of bits allocated to bone's ''rz'' in bitstream
|Number of bits allocated to bone's rotation delta Z in bitstream
|{{check}}
|{{check}}
|-
|-
|0xF
|0xF
|2
|u16
|u16
|translation_key_count
|'''Translation Key Count'''
|If this bone channel has an animated translation, its value will match ''key_count'', otherwise the value will be 0.  
|If this bone channel has an animated translation, its value will match ''Rotation Key Count''; otherwise the value will be 0.  
'''If the value is 0, this descriptor ends here'''
'''If the value is 0, the remaining Translation fields aren't present'''
|{{check}}
|{{check}}
|-
|-
|0x11
|0x11
|2
|s16
|s16
|initial_tx
|'''Initial Translation X'''
|Initial X value of bone's translation vector
|Initial X value of bone's translation vector
|{{check}}
|{{check}}
|-
|-
|0x13
|0x13
|1
|u8
|u8
|q_tx
|'''Translation Bits X'''
|Number of bits allocated to bone's ''tx'' in bitstream
|Number of bits allocated to bone's translation delta X in bitstream
|{{check}}
|{{check}}
|-
|-
|0x14
|0x14
|2
|s16
|s16
|initial_ty
|'''Initial Translation Y'''
|Initial Y value of bone's translation vector
|Initial Y value of bone's translation vector
|{{check}}
|{{check}}
|-
|-
|0x16
|0x16
|1
|u8
|u8
|q_ty
|'''Translation Bits Y'''
|Number of bits allocated to bone's ''ty'' in bitstream
|Number of bits allocated to bone's translation delta Y in bitstream
|{{check}}
|{{check}}
|-
|-
|0x17
|0x17
|2
|s16
|s16
|initial_tz
|'''Initial Translation Z'''
|Initial Z value of bone's translation vector
|Initial Z value of bone's translation vector
|{{check}}
|{{check}}
|-
|-
|0x19
|0x19
|1
|u8
|u8
|q_tz
|'''Translation Bits Z'''
|Number of bits allocated to bone's ''tz'' in bitstream
|Number of bits allocated to bone's translation delta Z in bitstream
|{{check}}
|{{check}}
|-
|0x1A
|u16
|'''Scale Key Count'''
|If this bone channel has an animated scale, its value will match ''Scale Key Count''; otherwise the value will be 0.
'''If the value is 0, the remaining Scale fields aren't present'''
|{{nocheck}}
|{{check}}
|-
|0x1C
|s16
|'''Initial Scale X'''
|Initial X value of bone's scale vector
|{{nocheck}}
|{{check}}
|-
|0x1E
|u8
|'''Scale Bits X'''
|Number of bits allocated to bone's scale delta X in bitstream
|{{nocheck}}
|{{check}}
|-
|0x1F
|s16
|'''Initial Scale Y'''
|Initial Y value of bone's scale vector
|{{nocheck}}
|{{check}}
|-
|0x21
|u8
|'''Scale Bits Y'''
|Number of bits allocated to bone's scale delta Y in bitstream
|{{nocheck}}
|{{check}}
|-
|0x22
|s16
|'''Initial Scale Z'''
|Initial Z value of bone's scale vector
|{{nocheck}}
|{{check}}
|-
|0x24
|u8
|'''Scale Bits Z'''
|Number of bits allocated to bone's scale delta Z in bitstream
|{{nocheck}}
|{{check}}
|-
|0x25
|colspan=5 {{unknown|End of descriptor}}
|}
|}


[[Category:File Formats]]
[[Category:File Formats]]
[[Category:Metroid Prime]]
[[Category:Metroid Prime]]
[[Category:Metroid Prime 2: Echoes]]

Latest revision as of 05:48, 3 March 2017

This article is for the ANIM format used in Metroid Prime and Metroid Prime 2: Echoes. See ANIM (File Format) for the other revisions of this format.

The ANIM format is used in conjunction with CINF + CSKR rigging to animate CMDL meshes. The format is largely the same between the two games, with the main difference being that starting in Metroid Prime 2, support for animating scale was added.

There are two versions of the ANIM format (indicated by the file's first u32 value), one with compressed animations and one with uncompressed ones:

Version Description
0x0 Quaternion Array Format (Uncompressed)
0x2 Rotation Vector Bitstream Format (Compressed)

Quaternion Array Format (Uncompressed)

The Quaternion Array Format (0x0) is a less common animation format. In Metroid Prime, it only appears in a Ridley intro animation and the rotating pirate data artifact hologram above the Impact Crater, as well as some unused Samus animations, while in Metroid Prime 2, it only seems to show up in some draft/test animations not used in the final game.

This format stores uncompressed animations by mapping animation channels to bones, supplying rotations as an array of quaternion (WXYZ) keys and translations/scales as an array of XYZ keys. Translations may be specified for a subset of bones as an array of XYZ keys. In Metroid Prime, rotation keys are required on every channel, while translations may be specified for a subset of bones. In Metroid Prime 2, all three transform components are opt-in.

Layout

Offset Type Element Count Name Notes MP1 MP2
0x4 Char Anim Time 1 Duration Time in seconds that the animation plays for ✔ ✔
0xC Char Anim Time 1 Key Interval Time in seconds between keys of each bone channel (reciprocal of frame-rate) ✔ ✔
0x14 u32 1 Key Count Count of keys for each bone channel (keys are set for every frame of the animation) ✔ ✔
0x18 u32 1 Root Bone ID ID of the root bone in this ANIM ✔ ✔
0x1C u32 1 Bone Channel Count Count of bone channel indices in the next array. Always 100. ✔ ✔
0x20 u8 Bone Channel Count Bone Channel Index Array This table maps each bone to a bone channel, with the index-position corresponding to a Bone ID in the associated CINF, while the value corresponds to a bone channel index. The value is 0xFF if the bone is not animated by this ANIM. ✔ ✔
u32 1 Rotation Channel Index Count Count of rotation channel indices in the next array. Matches the number of valid bone channels. ✖ ✔
u8 Rotation Channel Index Count Rotation Channel Index Array This table maps each bone channel to a rotation channel, with the index-position corresponding to an entry in the Bone Channel Index Array above (disregarding 0xFF entries), while the value corresponds to the index of a rotation channel. The value is 0xFF if the bone is not rotated by this ANIM. Note: In Metroid Prime, every bone channel always has rotations, so this array is omitted. ✖ ✔
u32 1 Translation Channel Index Count Count of translation channel indices in the next array. Matches the number of valid bone channels. ✔ ✔
u8 Translation Channel Index Count Translation Channel Index Array This table maps each bonechannel to a translation channel, with the index-position corresponding to an entry in the Bone Channel Index Array above (disregarding 0xFF entries), while the value corresponds to the index of a translation channel. The value is 0xFF if the bone is not translated by this ANIM. ✔ ✔
u32 1 Scale Channel Index Count Count of scale channel indices in the next array. Matches the number of valid bone channels. ✖ ✔
u8 Scale Channel Index Count Scale Channel Index Array This table maps each bone channel to a scale channel, with the index-position corresponding to an entry in the Bone Channel Index Array above (disregarding 0xFF entries), while the value corresponds to the index of a scale channel. The value is 0xFF if the bone is not scaled by this ANIM. ✖ ✔
u32 1 Scale Key Count Count of elements in Scale Key Array below ✖ ✔
float3 Scale Key Count Scale Key Array The scale keys are interleaved as such (bone-major): 
|------------|------------|-----|------------|
| bone0/key0 | bone0/key1 | ... | bone0/keyN |
| bone1/key0 | bone1/key1 | ... | bone1/keyN |
| .......... | .......... | ... | .......... |
| boneN/key0 | boneN/key1 | ... | boneN/keyN |
|------------|------------|-----|------------|
✖ ✔
u32 1 Rotation Key Count Count of elements in Rotation Key Array below ✔ ✔
float4 Rotation Key Count Rotation Key Array The rotation keys are interleaved the same way as the scale keys. In Metroid Prime 2, any bone channels that were marked 0xFF in the Rotation Channel Index Array are skipped. ✔ ✔
u32 1 Translation Key Count Count of elements in Translation Key Array below ✔ ✔
float3 Translation Key Count Translation Key Array The translation keys are interleaved the same way as the scale keys. Any bone channels that were marked 0xFF in the Translation Channel Index Array are skipped. ✔ ✔
EVNT 1 EVNT Ref ID for this ANIM's EVNT resource, or 0xFFFFFFFF if no events triggered ✔ ✖

Rotation Vector Bitstream Format (Compressed)

The Rotation Vector Bitstream Format (0x2) is the most widely used animation format. The format uses a compressed bitstream to store keys that have been delta encoded and quantized to make for a very compact, compressed animation. The data is processed sequentially to reconstruct the uncompressed bone channel data as quaternions.

In addition to the bitstream quantization, the format includes a bitmap specifying which frames of the animation have keys added. Consequently, the runtime generates missing keys via interpolation (reducing animation size further).

Key Values

When decoding the animation, each bone's attribute values are initialized to the Initial * values in the bone channel descriptors. For every frame of every bone channel, the key value in the bitstream is added with the previous key value (to resolve the delta encoding).

Once resolved, rotation components are divided by Rotation Divisor, resulting in an axis-angle rotation vector. This rotation vector is converted to quaternion imaginary components with the W component derived via normalized-difference and a sign-bit packed into the bitstream: 

q = π / 2.0 / rotation_divisor
X = sin(rx * q)
Y = sin(ry * q)
Z = sin(rz * q)
W = sqrt(MAX((1.0 - (X*X + Y*Y + Z*Z)), 0.0))
W = sign_bit ? -W : W

Translation components are multiplied by Translation Multiplier, and scale components are multiplied by Scale Multiplier.

Layout

Type Element Count Name Notes MP1 MP2
u32 1 Scratch Size Amount of memory that the animation system needs to allocate to process animation ✔ ✔
EVNT 1 EVNT Ref ID for this ANIM's EVNT resource, or 0xFFFFFFFF if no events triggered ✔ ✖
u32 1 Unknown 1 Always 0x1 ✔ ✖
u16 1 Unknown 2 ✖ ✔
float 1 Duration Time in seconds that the animation plays for ✔ ✔
float 1 Interval Time in seconds between frames (reciprocal of frame-rate, typically 30-fps) ✔ ✔
u32 1 Root Bone ID ID of the root bone in this ANIM ✔ ✔
u32 1 Looping Flag When non-zero, engine identifies this ANIM as looping ✔ ✔
u32 1 Rotation Divisor Rotation vectors are divided by this value before being applied ✔ ✔
float 1 Translation Multiplier Translation vectors are multiplied by this value before being applied ✔ ✔
float 1 Scale Multiplier Scale vectors are multiplied by this value before being applied ✖ ✔
u32 1 Bone Channel Count Count of bone channels present in ANIM ✔ ✔
u32 1 Unknown 4 Always 0x1 ✔ ✔
u32 1 Key Bitmap Length Number of bits in Key Bitmap ✔ ✔
u32 round_up(Key Bitmap Length / 32) Key Bitmap Word-packed bitmap. Each word is read from least-significant to most-significant bit. A set bit indicates the frame at the bit's position has keys for each bone channel. If the bit is unset, the keys must be generated via interpolation. ✔ ✔
u32 1 Bone Channel Count Count of animated bone channels (matches the previous bone channel count) ✔ ✖
u32 1 Bone Channel Descriptor Count Count of bone channel descriptors in Bone Channel Descriptor Table. Matches the Bone Channel Counts. ✔ ✔
Bone Channel Descriptor Bone Channel Descriptor Count Bone Channel Descriptor Table Table describing animated bone channels ✔ ✔
u32 <remainder of file> Key Bitstream Word-packed bitstream laid out as described by the descriptor table. The bitstream is unpacked just like Key Bitmap (least-significant to most-significant).

Key values are tightly-packed, quantized integers whose bit-depth is specified by the * Bits values in the descriptor table. Each bone-channel key-set starts with a single bit providing the W sign-bit (1 for negative, 0 for positive).

The key integers are signed using Two's complement representation.

The keys are interleaved as such (key-major): 

|------------|------------|-----|------------|
| bone0/key0 | bone1/key0 | ... | boneN/key0 |
| bone0/key1 | bone1/key1 | ... | boneN/key1 |
| .......... | .......... | ... | .......... |
| bone0/keyN | bone1/keyN | ... | boneN/keyN |
|------------|------------|-----|------------|
✔ ✔

Bone Channel Descriptor

Offset Type Name Notes MP1 MP2
0x0 u32 Bone ID Bone ID in the associated CINF for this bone channel ✔ ✔
0x4 u16 Rotation Key Count Number of rotation keys in the bitstream for this bone channel.

In MP2, if this value is 0, the remaining Rotation fields aren't present

✔ ✔
0x6 s16 Initial Rotation X Initial X value of bone's rotation vector ✔ ✔
0x8 u8 Rotation Bits X Number of bits allocated to bone's rotation delta X in bitstream ✔ ✔
0x9 s16 Initial Rotation Y Initial Y value of bone's rotation vector ✔ ✔
0xB u8 Rotation Bits Y Number of bits allocated to bone's rotation delta Y in bitstream ✔ ✔
0xC s16 Initial Rotation Z Initial Z value of bone's rotation vector ✔ ✔
0xE u8 Rotation Bits Z Number of bits allocated to bone's rotation delta Z in bitstream ✔ ✔
0xF u16 Translation Key Count If this bone channel has an animated translation, its value will match Rotation Key Count; otherwise the value will be 0.

If the value is 0, the remaining Translation fields aren't present

✔ ✔
0x11 s16 Initial Translation X Initial X value of bone's translation vector ✔ ✔
0x13 u8 Translation Bits X Number of bits allocated to bone's translation delta X in bitstream ✔ ✔
0x14 s16 Initial Translation Y Initial Y value of bone's translation vector ✔ ✔
0x16 u8 Translation Bits Y Number of bits allocated to bone's translation delta Y in bitstream ✔ ✔
0x17 s16 Initial Translation Z Initial Z value of bone's translation vector ✔ ✔
0x19 u8 Translation Bits Z Number of bits allocated to bone's translation delta Z in bitstream ✔ ✔
0x1A u16 Scale Key Count If this bone channel has an animated scale, its value will match Scale Key Count; otherwise the value will be 0.

If the value is 0, the remaining Scale fields aren't present

✖ ✔
0x1C s16 Initial Scale X Initial X value of bone's scale vector ✖ ✔
0x1E u8 Scale Bits X Number of bits allocated to bone's scale delta X in bitstream ✖ ✔
0x1F s16 Initial Scale Y Initial Y value of bone's scale vector ✖ ✔
0x21 u8 Scale Bits Y Number of bits allocated to bone's scale delta Y in bitstream ✖ ✔
0x22 s16 Initial Scale Z Initial Z value of bone's scale vector ✖ ✔
0x24 u8 Scale Bits Z Number of bits allocated to bone's scale delta Z in bitstream ✖ ✔
0x25 End of descriptor
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