Unity Asset Hex Fiend Template

UnityAssets.tcl

# Hex Fiend Template for Unity Asset Files
# By Tristan Hume
# Based on inspection and reading the code for https://github.com/Perfare/AssetStudio
# See https://github.com/ridiculousfish/HexFiend/blob/master/templates/Tutorial.md
# Only supports the Unity version Beat Saber uses and Beat Saber's MonoBehaviors

# Match Unity Version 2018.
requires 20 "32 30 31 38 2E"

proc align_stream {align} {
  set misalign [expr {$align - [pos] % $align}]
  if {$misalign < $align} {
    move $misalign
  }
}

proc c_string {name} {
  set length 1
  while {[uint8] != 0} {
    incr length
  }
  move -$length
  ascii $length $name
}

proc aligned_string {name} {
  set length [uint32]
  if {$length > 0} {
    str $length "utf8" $name
    align_stream 4
  } else {
    move -4
    bytes 4 $name
  }
}

proc object_ref {name} {
  section $name {
    # index in export table
    uint32 "File ID"
    # this is 1 if exterior, object index+1 if interior
    uint64 "Path ID"
  }
}

proc beatmap_difficulties {} {
  set difficulties_count [uint32 "Difficulties Count"]
  for {set i 0} {$i < $difficulties_count} {incr i} {
    section "Difficulty $i" {
      uint32 "Difficulty"
      uint32 "Rank"
      float "Note Jump Movement Speed"
      uint32 "Note Jump Start Beat Offset"
      object_ref "Beatmap Data"
    }
  }
}

proc beatmap_level {} {
  aligned_string "Level ID"
  aligned_string "Song Name"
  aligned_string "Sub Name"
  aligned_string "Author Name"
  aligned_string "Level Author"
  object_ref "Audio Clip"
  float "BPM"
  float "Time Offset"
  float "Shuffle"
  float "Shuffle Period"
  float "Preview Start Time"
  float "Preview Duration"
  # Dunno why song duration is missing in the data
  # float "Song Duration"
  object_ref "Cover Image"
  object_ref "Environment"

  set sets_count [uint32 "Beatmap Set Count"]
  for {set i 0} {$i < $sets_count} {incr i} {
    section "Set $i" {
      object_ref "Characteristic"
      beatmap_difficulties
    }
  }
}

proc beatmap_data {} {
  aligned_string "JSON Data"
  set sig_len [uint32 "Signature Length"]
  hex $sig_len "Signature"
  set data_len [uint32 "Data Length"]
  bytes $data_len "Projected Data"
}

proc level_collection {} {
  set sets_count [uint32 "Level Count"]
  for {set i 0} {$i < $sets_count} {incr i} {
    object_ref "Level $i"
  }
}

proc audio_clip {} {
  aligned_string "Name"

  uint32 "Load Type"
  uint32 "Channels"
  uint32 "Frequency"
  uint32 "Bits Per Sample"
  float "Length"
  uint8 "Is Tracker"
  align_stream 4
  uint32 "Subsound Index"
  uint8 "Preload Audio"
  uint8 "Background Load"
  uint8 "Legacy 3D"
  align_stream 4

  aligned_string "Source"
  uint64 "Offset"
  uint64 "Size"

  # 0 = PCM, 1 = Vorbis, 3 = MP3
  uint32 "Compression Format"
}

big_endian
section "Header" {
  set meta_s [uint32 "Metadata Size"]
  set file_size [uint32 "File Size"]
  uint32 "Generation"
  set data_offset [uint32 "Data Offset"]
  uint32 "Is Big Endian"
}
little_endian
section "Metadata" {
  # ascii 12 "Unity Version"
  c_string "Unity Version"
  uint32 "Target Platform"

  uint8 "Enable Type Tree"
  set type_count [uint32 "Type Count"]
  set types_classes [dict create]
  section "Types" {
    for {set i 0} {$i < $type_count} {incr i} {
      section [expr $i + 1] {
        set class_id [uint32 "Class ID"]
        dict set types_classes $i $class_id
        uint8 "Is Stripped"
        int16 "Script Type Index"
        if {$class_id == 114} {
          hex 16 "Script ID"
        }
        hex 16 "Type Hash"
      }
    }
  }

  set object_count [uint32 "Object Count"]
  set objects [list]
  section "Objects" {
    for {set i 0} {$i < $object_count} {incr i} {
      section [expr $i] {
        align_stream 4
        uint64 "Path ID"
        set offset [uint32 "Byte Offset"]
        uint32 "Byte Size"
        set type_id [uint32 "Type ID"]
        set class_id [dict get $types_classes $type_id]
        entry "Class ID" $class_id
        lappend objects [dict create offset $offset id $i class_id $class_id]
      }
    }
  }

  set script_count [uint32 "Script Count"]
  section "Scripts" {
    for {set i 0} {$i < $script_count} {incr i} {
      section [expr $i] {
        uint32 "File Index"
        align_stream 4
        uint64 "In-File ID"
      }
    }
  }

  set externals_count [uint32 "Externals Count"]
  section "Externals" {
    for {set i 0} {$i < $externals_count} {incr i} {
      section [expr $i] {
        c_string "Temp Empty"
        hex 16 "GUID"
        uint32 "Type"
        c_string "Path Name"
      }
    }
  }
}
goto $data_offset
set data_len [expr {$file_size - $data_offset}]
section "Data" {
  # bytes $data_len "Data"
  foreach object $objects {
    set object_offset [dict get $object offset]
    set object_id [dict get $object id]
    set object_class [dict get $object class_id]
    goto [expr {$data_offset + $object_offset}]
    if {$object_class == 114} {
      section "$object_id: MonoBehavior" {
        object_ref "GameObject"
        uint32 "Enabled"
        uint32 "Script Export ID"
        set kind [uint64 "Kind"]
        # TODO
        # section "Script" {
        #   uint32 "Execution Order"
        #   hex 16 "Properties Hash"
        #   aligned_string "Class Name"
        # }
        aligned_string "Name"

        # BeatmapLevelSO
        if {$kind == 644} {
          beatmap_level
        } elseif {$kind == 762} {
          level_collection
        } elseif {$kind == 1552} {
          beatmap_data
        }
      }
    } elseif {$object_class == 83} {
      section "$object_id: AudioClip" {
        audio_clip
      }
    }
  }
}