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OBD:Instance file format: Difference between revisions
I'm guessing that no one ever looked closely at this "signature" before, but it's actually more useful than that; explaining total checksum a little more
(what the #$%!ing @$&^ just happened; reverting accidental edits) |
(I'm guessing that no one ever looked closely at this "signature" before, but it's actually more useful than that; explaining total checksum a little more) |
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The level 0 files do not actually contain a level, but instances (resources) shared across all levels. Level 0 is loaded when the game starts, and never unloaded. All other level files, 1-19, are only loaded when their corresponding level starts, and unloaded when it ends. Since Oni can only hold these two levels in memory concurrently, resources have to be duplicated on disk whenever a character class, sound effect, etc. occurs in more than one level. For instance, although there are only 2,380 unique sounds in the game, there are 7,386 sounds stored across all level data files. | The level 0 files do not actually contain a level, but instances (resources) shared across all levels. Level 0 is loaded when the game starts, and never unloaded. All other level files, 1-19, are only loaded when their corresponding level starts, and unloaded when it ends. Since Oni can only hold these two levels in memory concurrently, resources have to be duplicated on disk whenever a character class, sound effect, etc. occurs in more than one level. For instance, although there are only 2,380 unique sounds in the game, there are 7,386 sounds stored across all level data files. | ||
{{TOClimit}} | |||
==Backwards and garbage data== | ==Backwards and garbage data== | ||
During development, Oni had an [[level0_Tools|in-game editor]] which presented a GUI for manipulating AIs, particles, etc. in a level. When a developer saved his work, the contents of the level, stored in RAM, were written directly to disk. Thus, the structure of the .dat/.raw/.sep files reflects the way in which Bungie West chose to store levels in memory. So when we read the data in the files with a hex editor, we can see eccentricities such as blank space and garbage data that represent various RAM contents from the developer's PC such as padding and pointers. | During development, Oni had an [[level0_Tools|in-game editor]] which presented a GUI for manipulating AIs, particles, etc. in a level. When a developer saved his work, the contents of the level, stored in RAM, were written directly to disk. Thus, the structure of the .dat/.raw/.sep files reflects the way in which Bungie West chose to store levels in memory. So when we read the data in the files with a hex editor, we can see eccentricities such as blank space and garbage data that represent various RAM contents from the developer's PC such as padding and pointers. | ||
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{{Table}} | {{Table}} | ||
{{OBD_Table_Header}} | {{OBD_Table_Header}} | ||
{{OBDtr| 0x00 | int64 | | 1F 27 DC 33 DF BC 03 00 | 0x0003BCDF33DC271F | Windows | {{OBDtr| 0x00 | int64 | | 1F 27 DC 33 DF BC 03 00 | 0x0003BCDF33DC271F | Windows instance file total template checksum; Windows demo and Mac retail/demo use 0x0003BCDF23C13061 instead }} | ||
{{OBDtr| 0x08 | int32 | | 31 33 52 56 | 'VR31' | .dat version; OniSplit's .oni files use 'VR32' instead }} | {{OBDtr| 0x08 | int32 | | 31 33 52 56 | 'VR31' | .dat version; OniSplit's .oni files use 'VR32' instead }} | ||
{{OBDtr| 0x0C | | {{OBDtr| 0x0C | int16 | | 40 00 | 64 | size of this header }} | ||
{{OBDtr| 0x0E | int16 | | 14 00 | 20 | size of instance descriptor }} | |||
{{OBDtr| 0x10 | int16 | | 10 00 | 16 | size of template descriptor }} | |||
{{OBDtr| 0x12 | int16 | | 08 00 | 8 | size of name descriptor }} | |||
{{OBDtr| 0x14 | int32 | | 83 24 00 00 | 9347 | instance descriptor count }} | {{OBDtr| 0x14 | int32 | | 83 24 00 00 | 9347 | instance descriptor count }} | ||
{{OBDtr| 0x18 | int32 | | D4 1B 00 00 | 7124 | name descriptor count }} | {{OBDtr| 0x18 | int32 | | D4 1B 00 00 | 7124 | name descriptor count }} | ||
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The file's '''template checksum''' tells us that this level data is in the .dat/.raw file scheme, | The file's '''total template checksum''' is the sum of all the template checksums (see "Template descriptors" below). Oni looks at this number in order to validate that it can read this version of the game data format. In practical terms, the total checksum value given for Windows above tells us that this level data is in the .dat/.raw file scheme, and the value given for Mac Oni and the Windows demo tells us that the level data uses the .dat/.raw/.sep file scheme. | ||
The '''version''' of the instance file is the format version. Reading it backwards, as discussed under the "Backwards and garbage data" section, we get "VR31", which is probably "version 31". This is the format version of all instance files in all releases of Oni, regardless of file scheme. | The '''version''' of the instance file is the format version. Reading it backwards, as discussed under the "Backwards and garbage data" section, we get "VR31", which is probably "version 31". This is the format version of all instance files in all releases of Oni, regardless of file scheme. | ||