FF8/FileFormat X

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Revision as of 21:40, 23 December 2020 by Sebanisu (talk | contribs) (→‎Camera Animation (WIP): I'm trying to fix this.)

By MaKiPL. Thanks for help in research for: shakotay2 (XeNTaX), Halfer, Yagami Light. Complete list of original battle stages by Kaspar01: List of battle stages

Contents

Info

.X file is uncompressed 3D stage model with texture embedeed. The file contains unused info (not used by FF8 engine), camera data, movement, translations and geometry data.

Battle stages DOES NOT contain pointers to next sections. All pointers are HARDCODED in FF8.EXE. Click me for battle stage pointer list

Name Usually starting with: Description
PlayStation MIPS assembly E8 FF BD 27 01 00 02 Used only in PS version; skipped in PC
Camera data + movement 02 00 08 00 20 00 Camera animations, movement (pre-keyed)
Model section 06 00 00 00 (See geometry section info) Divides to object (group) and it's sub-objects + vert/triangle grouping
Texture 10 00 00 00 09 (Always) Contains one .TIM texture, 8 BPP

How is this file handled by the engine?

FF8 loads specific file and reads it from hardcoded (written in FF8 code) position (or reads MIPS PlayStation assembly that contains battle stage load code). This hardcoded position points to camera data (in PC). Camera data has size uint16, which is calculated and relative jump is made. Just after camera, a typical section based file handling is made.

Offset Length Description
0 uint32 Number of sections
4 uint32 Objects group #1
8 uint32 Objects group #2
12 uint32 Objects group #3
16 uint32 Objects group #4
20 uint32 Texture [unused in code]
24 uint32 Texture
28 uint32 Relative to EOF

Objects Group

Offset Length Description
0 uint32 Number of sections
4 uint32 Pointer to Settings #1
8 uint32 Pointer to ObjectsList
12 uint32 Pointer to Settings #2
16 uint32 Relative to end_of_group
Objects List
Offset Length Description
0 uint32 Number of objects
Num_of_obj*4 uint32 Relative pointer to segment (one .obj file) [01 00 01 00]
Settings 1
Offset Length Description
0 uint16 Unknown, fixed 2?
2 sint16 (probably, or uint16) Scale (01 is the smallest)
4 4 bytes PADDING
8 4 bytes Nothing?
12 4 bytes Nothing?
16 2 bytes if not FF FF, then model vanishes
18 sint16 X or Z Axis rot origin (Translation)
20 44 bytes Left null for storing some engine data AFTER loaded in-game
64 2 bytes if not FF FF or 00 00, then model vanishes
66 2 bytes Nothing?
68 ...up to end Left null for storing some engine data AFTER loaded in-game

This might look difficult, but it's like multi-pointer file that starts at different location given by executable. See list at the beginning of this wiki to see which stages camera starts at which position (where FF8.exe really starts to read file as BattleStage) [FF8 stores whole file, even with useless data before camera] If this still makes trouble, see this video: TODO

Camera data

Starts at ~0x5d4 (see How the engine handles this file?). [.text:00509820]

Offset Length Description
0 uInt16 Pointers count. Fixed (02 00) [Unused in code]
2 uInt16 Relative jump to CameraSetting. Should be (08 00)
4 uInt16 Relative jump to CameraAnimationCollection. Should be (20 00)
6 uInt16 Camera data size (starting from 0) [unused in code]
8 24 bytes Camera Settings
32 ?? bytes Camera Animation Collection

Camera Setting

Offset Length Description
0 char (based on disassembly) CameraAnimMode?
1 byte? StopEnemyBeforeAnim?
2 Bitfield? (1B) UHM?
3 ??? DefaultEndofCameraPosition_Zoom?
4 ??? ???

Camera Animations Collection

Offset Length Description
0 uint16 NumOfSets
2 *(Set index) uint16 Relative pointer to camera Animation Set
2 *(Set index)+ 2 uint16 Camera EOF
CameraAnimationSetPointer CameraAnimationSet CameraAnimationSet
CameraAnimationSet

Seems to be 8 pointers in each set.

Offset Length Description
0 ushort AnimPointer*2
AnimPointer Varies 144-146-148 bytes usually CameraAnimation

Camera Animation (WIP)

All this is based on best effort knowledge from reversing by Maki. I'm just trying to understand it.

Control Word

Offset Length Description
0 uint16_t (bit varies) Main controller. If 0xFFFFU END

FOV

Control Word & 0b0000'0000'1100'0000U
1 Default
Offset Length Description
None None Start = 0x200
None None End = 0x200
2 Same
Offset Length Description
0 uint16_t Start
2 uint16_t Padding
None None End = Start
2 Different
Offset Length Description
0 uint16_t Start
2 uint16_t Padding
4 uint16_t End

ROLL

Control Word & 0b0000'0011'0000'0000U
0 Unknown
TODO
1 Default
Offset Length Description
None None Start = 0x000
None None End = 0x000
2 Same
Offset Length Description
0 uint16_t Start
None None End = Start
2 Different
Offset Length Description
0 uint16_t Start
2 uint16_t End

LAYOUT

Control Word & 0b0000'0000'0000'0001U
0 Default
You'll loop through the data till the first value is less than 0. pushing back to a variable length container.
Offset Length Description
0 int16_t if < 0 break; could be related to time of frame.
2 28 bytes Animation Frame
1 Other
TODO

Time

Time is calculated from number of frames. You basically set starting position World+lookat and ending position, then mark number of frames to interpolate between them. Every frame is one draw call and it costs 16. Starting time needs to be equal or higher for next animation frame to be read; If next frame==0xFFFF then it's all done.

Animation Frame

Offset Length Description
0 int16_t is frame durations shot
2 Vertice<uint16_t> (x,y,z) World
8 int16_t is frame ending shot
10 Vertice<uint16_t> (x,y,z) Look At
Dependency
  CAMERA:
  -Camera Settings
  -Camera Animation Collection (even three collections in a0stg006.x and up to 7 in a0stg101.x!)
     |
     |
      -Camera animation Set (Always 8 camera animations, may be empty (0xFFFF); look for example to a0stg127.x collectionId==1; there are 8 animations, but 7 of them are 0xFFFF (pointers increase by 2))
         |
         |
          - Camera animation


Example

a0stg006.x:
0x5d8 -> 02 00 08 00 20 00

  1. Get EOF-> *(0x5d8 + 8) -> 32
  2. Jump to EOF -> 0x5d8 + 32 = 0x5F8 (This is now Camera Animation Collection)
  3. Get pointer to correct anim collection. In this case we will use AnimCollectionID == 0, so: *(0x5F8 + 0*2 + 2) -> 0x0c
  4. Jump to Anim collection data: 0x5F8 + 0x0c = 0x604 (This is now Camera Animation Set)
  5. Jump to Camera animation by cameraAnimSetID, let's take for example cameraAnimSetID == 7, so: *(0x604 + 7*2) -> 0x25E. Now carefully, jump by multiplying it by 2!
    1. 0x604 + (0x25E * 2) = 0xAC0

Therefore: a0stg006.x Camera animation 7 in camera collection 0 is at 0xAC0

Geometry

Geometry contains groups, that contains Triangles and/or quads poligons. Models always stars at 01 00 01 00, and needs to be after camera data, either it's not model itself, but some other data.

Group

Offset Length Description
0 4 bytes Always 01 00 01 00 / Header of object
4 2 bytes Uint16 / number of vertices.
6 Number of vertices * 6 Vertex data, short X; short Y; short Z;
6 + (Number of vertices *6) (AbsolutePosition MOD 4) + 4 Padding
varies (just after above) 2 bytes uint16 / number of triangles
varies (just after above) 2 bytes uint16 / number of quads
varies (just after above) 4 bytes padding
varies (just after above) number of triangles * 20 Triangle data. If NumOfTriangles = 0, then instead of any triangle data, there's quad data.
varies (just after above) number of quads * 24 Triangle data. If NumOfQuads = 0, then instead of any quad data, there's either next header 01 00 01 00, or end of group.
Triangle
Name Type Description
F1 (A) uint16 A of face indice
F2 (B) uint16 B of face indice
F3 (C) uint16 C of face indice
U1 Byte U of first texture coordinate
V1 Byte V of first texture coordinate
U2 Byte U of second texture coordinate
V2 Byte V of second texture coordinate
CLUT_ID UInt16 (BIT operated)* Index to CLUT_ID operated by BIT (see below)
U3 Byte U of third texture coordinate
V3 Byte V of third texture coordinate
Special (see below / After QUAD table) 8 Byte See below (after QUAD table)
Hide Byte/Bool Bool. Hides or shows texture
Red Byte Texture colourization (Red)
Green Byte Texture colourization (Green)
Blue Byte Texture colourization (Blue)
PSone GPU related Byte PSOne instruction
Quad
Name Type Description
F1 (A) uint16 A of face indice
F2 (B) uint16 B of face indice
F3 (C) uint16 C of face indice
F4 (D) uint16 D of face indice
U1 Byte U of first texture coordinate
V1 Byte V of first texture coordinate
CLUT_ID UInt16 (BIT operated)* Index to CLUT_ID operated by BIT (see below)
U2 Byte U of second texture coordinate
V2 Byte V of second texture coordinate
Special (see below) 8 Byte See below (after table)
Hide Byte/Bool Bool. Hides or shows texture
U3 Byte U of third texture coordinate
V3 Byte V of third texture coordinate
U4 Byte U of fourth texture coordinate
V4 Byte V of fourth texture coordinate
Red Byte Texture colourization (Red)
Green Byte Texture colourization (Green)
Blue Byte Texture colourization (Blue)
PSone GPU related Byte PSOne instruction

Special Byte: This byte, needs to be divided to two bytes. So, for example, a 0xE5 needs to be treated like two bytes: 0x0E 0x05

Singular of char Example Description
First char/ 4 BIT B2 --> 0B Unknown
Second char / 4 BIT B2 --> 02 Texture page number

CLUT ID

The most important bit's are the first two on one byte, and last two on last byte. Example: 00000000 00111100 (00 3C) should be read like this: 00111100 00000000 (3C 00) And the CLUT ID is revealed by watching this four bits: 001111[00 00]000000

Same applies to reading CLUT colors (16bits) where they are: 1b-T, 5b-B, 5b-G, 5b-R (Or RGBT if reordered as shown above)

Complete list (without replacing bit order - as is in HEX editor/memory):

CLUT ID BIT HEX
#1 00000000 00111100 00 3C
#2 01000000 00111100 40 3C
#3 10000000 00111100 80 3C
#4 11000000 00111100 C0 3C
#5 00000000 00111101 00 3D
#6 01000000 00111101 40 3D
#7 10000000 00111101 80 3D
#8 11000000 00111101 C0 3D
#9 00000000 00111110 00 3E
#10 01000000 00111110 40 3E
#11 10000000 00111110 80 3E
#12 11000000 00111110 C0 3E
#13 00000000 00111111 00 3F
#14 01000000 00111111 40 3F
#15 10000000 00111111 80 3F
#16 11000000 00111111 C0 3F

Texture

Contains one TIMs with various size 512x256, 673x256, 768x256 (8BPP).

UV calculation algorithm

Float U = (float)U_Byte / (float)(TIM_Texture_Width * 2) + ((float)Texture_Page/(TIM_Texture_Width * 2));

Texture page calculation

Byte TPage = InputBytes[TexturePage_index] & 0F;

Bitwise TPage byte AND 0F, to delete first 4 bits 

int TPageINT = TPage * 64;

For 16 bit TIM's, the texture page is 64 pixels wide

Example

For 24-bit TIM: 

0xB2 byte is: 2*48 = 96

Unsure about this one. It could be 42.667 instead of 48. It takes 1.5x the space of 16 bit. I haven't seen a file that uses 24-bit yet.

For 16-bit TIM: 

0xB2 byte is: 2*64= 128

For 8-bit TIM: 

0xB2 byte is: 2*128 = 256

For 4-bit TIM: 

0xB2 byte is: 2*256 = 512

Each time you half the number of bits you double the amount of data you can store in the same space. So the calculated Texture Page is different.

Face order / Translation/ triangulation

Quad wing order

 ABCD ---> ABDC
 example:
  f 1 2 3 4
 to:
  f 1 2 4 3

Quad triangulation face order

 ABDC > ABD
        ACD (same for VT)
 example:
 f 1 2 4 3
 to:
 f 1 2 4
 f 1 3 4

Triangles VT order

 A/T1 > A/T2
 B/T2 > B/T3
 C/T3 > C/T1

Example

 (Also with quad triangulation face order!)
 f 1/1 2/2 7/4 6/3
 to:
 f 1/1 2/2 7/4
 f 1/1 6/3 7/4
 where:
 A=1 B=2 C=6 D=7
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