Revision as of 03:32, 12 May 2008

As they exist on the game CD, Chrono Cross character battle models consist of applicable textures followed by the model geometry itself. The model data begin with a header that points to various sections, and the sections have their own subheaders and subsections.

Below Serge's, Kid's, and Guile's models are employed as examples of how the model data (vertices, shaders, animations, etc) are structured within the model file itself. Keep in mind that all data is represented in "Little Endian" Mode, meaning we humans must employ a byte-order reversal technique to understand it. For example, 06 00 00 00 means 0x06, and F8 4E 00 00 means 0x4EF8.

Also keep in mind that offset ranges are relative, meaning pointer tables report locations that are are a certain number of bytes from the beginning of the current header/subheader. This makes no difference in the overall file header when you're looking at the model data file as excised from the game CD, but it most certainly affects the correct interpretation of subheaders. Therefore, the offsets reported in subheader pointer tables are accompanied by (true offsets) from the beginning of the model file.

Example 1: Serge

BATTLE MODEL HEADER...
OFFSETS  OFFSET VALUES
00000000 06 00 00 00 20 00 00 00-F8 4E 00 00 C8 50 00 00
00000010 28 52 00 00 CC A2 00 00-00 00 00 00 DC AB 00 00

Split into 4-byte chunks, the header can be interpreted in the following way. "Section1," etc., report the beginning offsets of each section:

Header Offset Range: 00 ~ 1F
6 Sections       | Section1 0x20   | Section2 0x4EF8 | Section3 0x50C8
Section4 0x5228  | Section5 0xA2CC | Section6 N/A    | End of File 0xABDC

SECTION 1 HEADER...
OFFSETS  OFFSET VALUES
00000020 02 00 00 00 14 00 00 00-80 02 00 00 05 02 2B 04
00000030 F9 00 00 00 38 03 00 00-C8 28 00 00 28 42 00 00

Section1 Offset Range: 20 ~ 4EF7
Section1 Header Offset Range: 20 ~ 40
*Pointer 0x02 | PointerTable Start 0x14(34)| ??? 0x0280              | * 0x042B0205
??? 0xF9      | Section 1-2 0x0338(0358)   | Section 1-3 0x28C8(28E8)| Section 1-4 0x4228(4248)

Section 1-1 (Vertex Assignment) Offset Range: 40 ~ 357
 Section 1-1 contains vertex assignments to the battle model skeleton. Its structure consists  
 of alternating series of 8-byte mode and 16-byte mode vertex assignments that match the
 pattern established in Section 1-3. Appended to the end of each 16-byte mode assignment series 
 is unknown data that may affect the model texture's application to the 3D data.
 
 Section 1-1 Map...
 0x40 ~ 0x8B: 8-byte mode vertex assignment header followed by assignments.
 0x8C ~ 0x28B: 16-byte mode vertex assignment header followed by assignments.
 0x28C ~ 0x2AB: Unknown data.
 0x2AC ~ 0x2B7: 8-byte mode vertex assignment header followed by assignments.
 0x2B8 ~ 0x343: 16-byte mode vertex assignment header followed by assignments.
 0x343 ~ 0x357: Unknown data.

 8-byte mode vertex assignment header format: #A #A #A #A 00 00 00 00
 8-byte mode vertex assignment format: NV NV JJ JJ
   Where...
    #A: Number of assignments that follow.
    NV: Next NV Vertices are assigned to JJ JJ.
    JJ: Index of the joint to which the body of vertices is assigned.

 16-byte mode vertex assignment header format: #A #A #A #A PP PP PP PP
 16-byte mode vertex assigment format: NV NV 00 00 J1 J1 W1 W1 J2 J2 W2 W2
   Where...
    #A: Number of assignments that follow.
    NV: Next NV Vertices are assigned to J1 J1 and J2 J2.
    PP: Pointer value necessary for the 16-byte mode vertex asignments. It is equivalent to the 
        length in bytes of the 8-byte mode vertex run in Section 1-3 from which the preceding 
        8-byte mode vertex assignments in this section are made.
    J1: Index of the first joint to which the body of vertices is assigned.
    W1: Weight of the association between NV and J1 for animation purposes.
    J2: Index of the second joint to which the body of vertices is assigned.
    W2: Weight of the association between NV and J2 for animation purposes.


Section 1-2(UV Texture Map) Offset Range: 358 ~ 28E7
 Section 1-2 Map...
 0x0358 ~ 0x0FB7: Triangle UV data and pointers (264 triangles)
 0x0FB8 ~ 0x2657: Quad UV data and pointers (362 quads)
 0x2658 ~ 0x26E7: Triangle UV data and pointers (12 triangles)
 0x26E8 ~ 0x28E7: Quad UV data and pointers (32 quads)
  Triangle UV data and pointer setup: U1 V1 U2 V2 U3 V3 P1 P1 - P2 P2 P3 P3
  Quad UV data and pointer setup:     U1 V1 U2 V2 U3 V3 U4 V4 - P1 P1 P2 P2 P3 P3 P4 P4
   ...where U? V? are pixel coordinates on the model texture; top-left corner is 0, 0.
   ...and P? P? are pointer values that tell the game engine which polygon the texture piece is 
      applied to.

Rules for interpreting quad pointers... Rule for Positive Pointers (as interpreted in hexadecimal)

• If you're in one of the first two columns, divide the byte pair value by 0x2, then by 0x8. This value is the index for the vertex to which the UV point is mapped.
• If you're in one of the last two columns, divide the byte pair value by 0x8. This value is the index for the vertex to which the UV point is mapped.

Rule for Negative Pointers (as interpreted in decimal)

• If you're in one of the first two columns, divide the byte pair value by 16. Go backward that number of positions into the non-UV data.
• If you're in one of the last two columns, divide the byte pair value by 8. Go backward that number of positions into the non-UV data.

Rules for interpreting triangle pointers... Rule for Positive Pointers (hex)

• If you're in the first column, divide the byte pair value by 0x8. This value is the vertex index.
• If you're in one of the last two columns, divide the byte pair value by 0x2, then by 0x8. This value is the vertex index.

Rule for Negative Pointers (dec)

• If you're in the first column, divide the byte pair value by 8. Go backward that number of positions into the non-UV data, adding an invisible position to the three extant positions.
• If you're in one of the last two columns, divide the byte pair value by 16. Go backward that number of positions into the non-UV data, adding an invisible position to the three extant positions.

• For triangles, switch pointers such that the first UV coordinate gets the second pointer; the second UV coordinate gets the third pointer; the third UV coordinate gets the first pointer. The pointers retain the division properties they had in their original positions.

Section 1-3(Vertex Pool) Offset Range: 28E8 ~ 4247
 Section 1-3 Map...
 0x28E8 ~ 0x324F: "8-byte mode", 301 vertices
 0x3250 ~ 0x3F6F: "16-byte mode", 210 vertices
 0x3F70 ~ 0x3F97: "8-byte mode", 5 vertices
 0x3F98 ~ 0x4247: "16-byte mode", 43 vertices
  "8-byte mode" setup...
   ZZ ** YY ** XX ** 00 00 - ZZ ** YY ** XX ** 01 00
   ZZ ** YY ** XX ** 02 00 - ZZ ** YY ** XX ** 03 00
  "16-byte mode" setup...
   ZZ ** YY ** XX ** 00 00 - ZZ ** YY ** XX ** 00 00
   ZZ ** YY ** XX ** 01 00 - ZZ ** YY ** XX ** 01 00
    Where...
    ZZ: Magnitude of coordinate on the up & down axis on the screen plane
    YY: Magnitude of coordinate on depth axis; toward or away from you with respect to the 
        screen.
    XX: Magnitude of coordinate on right & left axis on the screen plane
    **: A directional reverser byte. If 00, the vertex is placed in one direction on the axis, 
        and if FF, the vertex gets placed on a coordinate the same "magnitude" but opposite  
        direction on that axis. (In actuality, it merely specifies whether the value is 
        positive or negative in hex).
 ?? ??: The vertex index; two bytes per vertex.

    16-byte mode appears to come into play when a vertex is associated with more than one bone.
    * The first eight bytes represent the vertex's location relative to the first bone it is 
      associated with.
    * The second eight bytes represent the vertex's location relative to the second bone it is 
      associated with.

Section 1-4 Offset Range: 4248 ~ 4EF7
 Section 1-4 Pattern...
 ?? ?? ?? 00 ?? ?? ?? 00 - ?? ?? ?? 00 ?? ?? ?? 00
 ?? ?? ?? 00 ?? ?? ?? 00 - ?? ?? ?? 00 ?? ?? ?? 00
  The purpose of this SubSection is unknown; all data can be safely 00'd out and not affect   
  Serge's model shape or animations.

SECTION 2 (Skeleton) HEADER:
OFFSETS OFFSET VALUES
0004EF8 17 00 00 00

0x17, or 23, bones in the skeleton. Section 2 offset range 0x4EF8 ~ 0x50C8

Bone format...
PJ PJ PJ PJ XR XR YR YR - ZR ZR XC XC YC YC ZC ZC 
BI BI BI BI
 Where... 
 PJ = Index of parent joint (0xFFFF, or -1 if this bone has no parent joint) 
 XR = X rotation (range: 0XF000 ~ 0xFFF, or -4096 to 4095, where 4096 = 360 degrees) 
 YR = Y rotation (range: 0XF000 ~ 0xFFF, or -4096 to 4095, where 4096 = 360 degrees) 
 ZR = Z rotation (range: 0XF000 ~ 0xFFF, or -4096 to 4095, where 4096 = 360 degrees) 
 XC = X coordinate in 3D space relative to parent joint 
 YC = Y coordinate in 3D space relative to parent joint 
 ZC = Z coordinate in 3D space relative to parent joint 
 BI = Current bone index (0xFFFF, or -1 if current joint and parent joint do not form a bone)

Example 2: Kid

BATLE MODEL HEADER...
OFFSETS  OFFSET VALUES
00000000 06 00 00 00 20 00 00 00-B4 4D 00 00 C4 50 00 00
00000010 24 52 00 00 F0 C6 00 00-00 00 00 00 00 D0 00 00

Split into 4-byte chunks, the header and subheaders can be interpreted in the following way. "Section1," etc., report the beginning offsets of each section:

Header Offset Range: 00 ~ 1F
6 sections      | Section1 0x20    | Section2 0x4DB4   | Section3 0x50C4
Section4 0x5224 | Section5 0xC6F0  | Section6 N/A      | End of File 0xD000


SECTION 1 HEADER...
OFFSETS  OFFSET VALUES
00000020 02 00 00 00 14 00 00 00-38 02 00 00 D9 01 07 04
00000030 26 02 00 00 74 03 00 00-04 2C 00 00 64 42 00 00

Section1 Offset Range: 20 ~ 4DB3 
Section1 Header Offset Range: 20 ~ 40
*Pointer 0x02 | PointerTableStart 0x14(34)| ??? 0x0238              | * 0x040701D9
??? 0x0226    | Section 1-2 0x0374(0394)  | Section 1-3 0x2C04(2C24)| Section 1-4 0x4264(4284)

Section 1-1 Offset Range: 40 ~ 393
Section 1-2 (UV Texture Map) Offset Range: 394 ~ 2C23
Section 1-3 (Vertex Pool) Offset Range: 2C24 ~ 4283
Section 1-4 Offset Range: 4284 ~ 4DB3

Example 3: Guile

BATTLE MODEL HEADER...
OFFSETS  OFFSET VALUES
00000000 06 00 00 00 20 00 00 00-3C 4C 00 00 10 4F 00 00
00000010 70 50 00 00 1C E4 00 00-00 00 00 00 2C ED 00 00

Split into 4-byte chunks, the header can be read as follows:

Header Offset Range: 00 ~ 1F
6 Sections       | Section1 0x20    | Section2 0x4C3C  | Section3 0x4F10
Section4 0x5070  | Section5 0xE41C  | Section6 N/A     | End of File 0xED2C

SECTION 1 HEADER...
OFFSETS  OFFSET VALUES
00000020 05 00 00 00 20 00 00 00-D8 00 00 00 C6 01 00 00
00000030 B8 01 00 00 5C 02 00 00-4B 03 9A 04 BE 02 00 00
00000040 3C 03 00 00 38 2A 00 00-D0 40 00 00 

Section 1 Offset Range: 20 ~ 4C3B
Section 1 Header Offset Range: 20 ~ 4B
*Pointer 0x05              | PointerTableStart 0x20(40)| ??? 0xD8                 | ??? 0x016C
??? 0x01B8                 | ??? 0x025C                | * 0x049A034B             | ??? 0x02BE
Section 1-2 0x033C(035C)   | Section 1-3  0x2A38(2A58) | Section 1-4 0x40D0(40F0)

Section 1-1 Offset Range: 4C ~ 35B
Section 1-2 (UV Texture Map) Offset Range: 35C ~ 2A57
Section 1-3 (Vertex Pool) Offset Range: 2A58 ~ 40EF
Section 1-4 40F0 ~ 4C3B

Example 4: Flea

Example 5: Slash

DISCLAIMER: This is still a working entry. All interpretations are subject to change with time.

SPECIAL THANKS: To Gemini for identifying the battle textures that led us to the models; to Luminaire85 for finding and interpreting the headers and subheaders, fine-tuning various theories, and coding the model viewer; to MDenham for figuring out how the pointers and Section 1-1 work; and to Halkun, Cyberman and yaz0r for providing constant advice and guidance.