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openomf:af

HAR File Format (.AF)

The AF files contain all the information related to HARs; sprites, key-combos, projectile sprites, base damage, etc. The format is not entirely understood but a large portion has been dissected and understood. All AF files are broken up into the following sections:

Fighter Header

This contains the basic data about the HAR. Unmodified speeds, endurance, power, etc.

HAR Number 1 WORD Must be the same number as in the filename eg: FIGHTR1.AF
Unknown Data 2 bytes Always 10, Timing window for executing special moves, 1 for very small window, 100 for very large
Endurance 4 bytes Stun resistance Bar. Max is 548,801,280. Above or below that results in permanantly stunned state. Multiplied by 3.6 after loading
Unknown Data 1 byte Usually 2, exceptions from 1-50
Power 1 WORD Health or Hit Points, max is 8717.
Forward Speed 1 signed DWORD Speed at which the HAR moves towards opponent
Backward Speed 1 signed DWORD Speed at which HAR retreats from opponent
Upward Speed 1 signed DWORD Initial jump speed, this should be negative. Outside tournament mode, used value = 256 * (upward speed / 256 + jump height (in advanced menu) / 100)
Downward Speed 1 signed DWORD How quickly the HAR falls while being airborne, should be positive
Unknown Data 1 byte ? Always 0x32
Unknown Data 1 byte ? Always 0x14

There then follow a number of blocks. Each block starts with a one byte animation number.

Animation Number 1 BYTES Unique Identifier for animation (less than 70), end of animations (>= 70)

If this value is less than 70, then an Animation and a Move footer follows. A value of 70 or higher marks the end of animations, and the fighter footer follows.

Animation

Animation Header

X Start 1 SIGNED WORD Initial X position of sprite (unless spawned from another animation)
Y Start 1 SIGNED WORD Initial Y position of sprite (unless spawned from another animation)
Unknown Data 4 BYTES ??? - Seems to be [00 00 00 00] in all AF and BK files. Maybe just UDWORD null ?
Overlay Amount 1 WORD Number of DWORDS in the Overlay Table
Frame Count 1 BYTE How many frames in this animation
Collision Coordinate Table N DWORDS Contains the collision data. Check below for more info.
Collision coordinate table

The following applies for every DWORD in collision coordinate table.

Coordinate frame information 6 bits Frame index for x,y coordinate
Y coordinate 10 bits Y coordinate for the collision point
NULL 6 bits Always 0 ?
X coordinate 10 bits X coordinate for the collision point

So, for the current frame, you look at the collision table and use any points with the index for the current frame. The frames are 0 indexed.

Animation String Header

String Length 1 WORD Length of the string
String N BYTES Animation String
Unknown Data 1 BYTE Nul terminator
Number of Extra Strings 1 BYTE How many other animation strings there are

There then follow N extra animation strings, where N was the number specified in the Animation String Header. The extra strings are stored as follows:

Extra Animation Strings

String Length 1 WORD Length of string
String N BYTES Extra Animation String
Unknown Data 1 BYTE Nul terminator

Sprites

There then follow N sprites, where N is the frame count specified in the animation header, followed by the animation footer.

See Sprite format for the format of the sprites.

The first 21 bytes of the animation footer have an unknown purpose. Some possibilities are listed.

(Note: Unknown 1 & 3 removed, since they seem to be part of WORD Unk 0 and WORD Unk 2)

Unknown 0 1 WORD AI related bitmap ?
Unknown 2 1 WORD Seems to be related to airborne attacks, possibly constraints for positioning (near wall, etc)
0x1 Must be close to a wall
0x2 Must be airborne
0x4 Must be close to other HAR ?
0x20 ?
0x40 scrap/destruction constraint ?
0x2000 scrap/destruction/fire+ice ?
0x4000 scrap/destruction/fire+ice ?
Unknown 4 1 BYTE Not used ?
Unknown 5 1 BYTE Not used ?
Unknown 6 1 BYTE Not used ?
Unknown 7 1 BYTE Not used ?
Unknown 8 1 BYTE Not used ?
Unknown 9 1 BYTE Not used ?
Unknown 10 1 BYTE Not used ?
Unknown 11 1 BYTE Not used ?
Unknown 12 1 BYTE Next animation to play, if the current one hit
Unknown 13 1 BYTE Animation Category
0 - Misc.
2 - Close Quarters/Throw
4 - 'Low', 'l' tags
5 - 'Medium', 'm' tags
6 - 'High', 'h' tags
7 - Jumping, 'j' tags
8 - Projectile, 'p' tags
9 - Basic
11 - Victory/Defeat
12 - Scrap
13 - Destruction
These are just educated guesses, but they are definitely used by OMF to decide which animation to play when a player uses a specific key combo.
Unknown 14 1 BYTE Health/damage related ?
Unknown 15 1 BYTE Time to keep enemy stunned on block (Blockstun)
Pushback is applied during blockstun and the amount is calculated based on the duration
Unknown 16 1 BYTE The successor animation id
Unknown 17 1 BYTE Damage (Value divided by 2.0)
Unknown 18 1 BYTE Some sort of special animation selection. Maybe corner case fix of some sort ? Only used in collision handling.
0x20 - Move HAR backwards to fix overlap
Unknown 19 1 BYTE Extra string selection flag, describes which speed modifier should be used to select extra string. 1 = Arm, 2 = Leg, 3 = Special arm, 4 = special leg, 5 = arm+leg or some combination ?
Unknown 20 1 BYTE Points if this move hits, in hundreds (Multiplied by 4 after loading)
Move String 21 BYTES Move String NULL terminated (trailing data after the first NULL seems to be reusable to label animations)
Footer String Length 1 WORD Length of footer string
Footer String Length N BYTES Animation string for animation 9 on the other HAR if this move 'hits'
Unknown 1 BYTE ??? - 0 in all known AF/BK files. An animation tag of 's0' does not seem to play the sound stored in this byte.
Sounds 29 BYTES(?) Sound mapping table - when an animation string contains a tag like 's<n>', OMF looks at the Nth element of this table, which contains the ID of the sample to play from SOUNDS.DAT (numbered starting from 1, not 0). For example, INTRO.BK contains multiple instances of the 's1' tag. Position 1 in this table for INTRO.BK contains '15', which is the ID of the thunderclap sound in SOUNDS.DAT.

For all known AF files, the last 5 bytes are FGHED, which correspond to sounds 70, 71, 72, 69 and 68.

Sample Implementations

  • Link removed on request by Vagabond.

Magic Numbers

To check if a file is a valid AF file, there are 2 magic sequences you can check for:

  • Seek to the -31st byte (the 31st byte before the end of the file). The value is 250 for all known AF files, and is required to be >= 70.
  • The last 5 bytes in the file are the string 'FGHED'. This is the case for all known AF files.
openomf/af.txt · Last modified: 2022/06/12 09:55 by aokmaniac13