Issue 1: Sonic Adventure PC and DC model formats

SANiK · Dec 14, 2004

In hopes of getting more beginners interested in next gen hacking, I am going to be releasing my notes on the model formats and later on other formats. Do note, the point of these issues is to hopefully show that SEGA used the SAME format from game to game. The format first appeared in the game NiGHTs, then it got updated and was used in Sonic Adventure, to be updated and used again in the Dreamcast BIOS, then in SA2, then in PSO, etc. Due bear in mind that some notes may have errors and some are incomplete.

Issues that I will be releasing:

Issue 1: Sonic Adventure PC and DC model formats (version 2 of format)

Issue 2: Nights model format (version 1 of format)

Issue 3: Sonic Adventure 2 model format (version 3 of format)

Memory sizes that I use:

byte = 1 byte

word = 2 bytes

dword = 4 bytes

----------------

sbyte = 1 byte (signed)

sword = 2 bytes (signed)

sdword = 4 bytes (signed)

----------------

float = 4 bytes

pointer = 4 bytes

//SADXmdl structures
//Do note, unless it's already NULL, ALL pointers need a "key" subtracted from them for them to work. The key depends on the type of file the model is in.
/*Keys:
#define KEY 0x400000  //*.EXE
#define KEY 0x10000000  //*.DLL
#define KEY 0xC900000 //DC version
*/

typedef struct VERTEX
{
  float x;
  float y;
  float z;
} VERTEX;

typedef struct UV
{
  word u;
  word v;
} UV;

typedef struct POLY
{
  //If you use strips:
  byte strip_dir; //If this is 0xFF, you draw the strips in strip[1],strip[0],strip[2] order
  //If strip_dir is 0x00, you draw the strips in strip[0], strip[1],strip[2] order
  byte strip_total;

  /*Do remember, you draw strips like this:
  1) Read 3 strips
  2) Draw the 3 strips as a triangle
  3) Read 1 new strip (a strip is actually 1 vertex reference)
  4) Draw the new triangle using the 2 old strips and the newly read strip
  5) Go back to step 3
  In simple words, it's a list of triangles with two points shared between them
  */
  word *strip;
 
  //If you use triangles:
  word tri[3];

  //If you use quads:
  word quad[4];
} POLY;

typedef struct MESH
{
/*The upper byte in mat_flags tells what type of poly that poly points to.
If (mat_flags >> 8) == 0xC0, then use strips.
If (mat_flags >> 8) == 0x00, then use triangles
If (mat_flags >> 8) == 0x40, then use quads*/
  word mat_flags; 
  word poly_total;
  POLY *poly;      //The polys are stored as strips, triangles, or quads, based on the bits in the mat_flags
  dword PAttr;      //Not much is known
  dword PNormal;  //Not much is known
  dword VColor;    //Vertex color, not much is known
  UV *uv; //UV's are applied to the poly's and not to each vertex. Hence, one vertex can have 3 different UV's depending on the poly being drawn.
  dword _null; //This _null is not there for the DC version of SADX
} MESH;

typedef struct ATTACH
{
  VERTEX *vertex;
  VERTEX *normal;  //If normal is not null, then the model uses normals
  dword vertex_total; //The vertex_total is the same value which tells the normal total
  MESH *mesh;
  dword material; //Material struct was cracked by Dude, waiting for info for it. (This is actually a pointer to data)
  word mesh_total;
  word material_total;
  float center[3]; //Center of the sphere
  float radius;    //Radius of the sphere, used for collision
  dword _null; //This _null is not there for the DC version of SADX
} ATTACH;

typedef struct OBJECT
{
  dword flags;
  ATTACH *attach;
  float pos[3];
  float rot[3];
  float scale[3];
  OBJECT *child;
  OBJECT *relate;
} OBJECT;
Click to expand...

Hopefully that clears up how the structure works.
*gets to work on describing the Sonic Adventure 2 and NiGHTs model format*

Ripping models from files

Things to know:

The attach struct is ALWAYS before the OBJECT struct.

On the DC, the start of the object struct minus 0x5C = start of the ATTACH struct

On the PC, the start of the object struct minus 0x60 = start of the ATTACH struct

Why the difference in 0x5C and 0x60? Simple, variable dword _null is not there on the DC.

Now if we know where an object struct is, we can figure out the rest of the model.

We read an OBJECT struct from a file

We also keep track of where we read the OBJECT struct from.

Now, we subtract 0x5C or 0x60 from where we read the OBJECT struct from depending if we are on the PC or the DC.

If the OBJECT.attach - KEY /*The key depends on the file type*/ == file offset that we read the OBJECT struct from - 0x5C or 0x60 is true, then the OBJECT struct is for real.

Now we apply the KEY to all the pointers and load the model. (Do note that there may be more models in one file so you should keep searching actually)

If the OBJECT struct was a false alarm, we move the file offset 4 bytes up, and read an OBJECT struct in all over again. It's back to step one for us.

Click to expand...

*Refer to the Cult for newer versions of this guide if you think something might have been fixed up*

LOst · Dec 15, 2004

Then you can tell me, what 3D interface do Sonic Adventure for DC use?

QUADS? That's OpenGL right?

SANiK · Dec 15, 2004

Well, the models CAN support quads, but it's never used.

Sonic Adventure DX uses Direct-X due to Microsoft and SEGA teaming up in designing the Dreamcast. When they did this, they made a package to allow programming of DC games on the PC and then to easily port them to the DC with no changes. This is why SEGA (if they want) can easily make a PC port of Sonic Adventure 2.

LOst · Dec 15, 2004

SANiK said:

Well, the models CAN support quads, but it's never used.

Sonic Adventure DX uses Direct-X due to Microsoft and SEGA teaming up in designing the Dreamcast. When they did this, they made a package to allow programming of DC games on the PC and then to easily port them to the DC with no changes. This is why SEGA (if they want) can easily make a PC port of Sonic Adventure 2.
Click to expand...

Cool.

But how do you port SA DX to Gamecube and Playstation 2?

SANiK · Dec 15, 2004

SADX was never on the PS2...
As for the Gamecube, they probably made another library/package to port the game. This btw is not rare at all in the game industry.

LOst · Dec 15, 2004

Okay. I actually don't know much about 3-D worldspace coordinates and camera settings but I would like to learn.

And I noticed this:

Code (Text):

dword material; //Material struct was cracked by Dude, waiting for info for it. (This is actually a pointer to data)

should be dword*

And I would not mix up struct OBJECT and OBJECT. Put it like this:

Code (Text):

typedef struct _OBJECT

{

 struct _OBJECT *child;

} OBJECT;

SANiK · Dec 15, 2004

Okay. I actually don't know much about 3-D worldspace coordinates and camera settings but I would like to learn.
Click to expand...

Well, there's nothing much to it except that instead of the X and Y axis, you have the Z axis. A float is used to store fractional numbers (e.g. 100.23 )for anyone that didn't know.

And I noticed this:

Code (Text):

dword material; //Material struct was cracked by Dude, waiting for info for it. (This is actually a pointer to data)

should be dword*
Click to expand...

Nice that you noticed, but the reason it's a dword is because I don't have a structure to attach it to. (Dude needs to finish cracking the rest)
If Dude does finish the material struct, it would become this then:
MATERIAL *material; //Points to a material structure

But doing dword material will prevent someone from mistakenly pointing to unknown regions.

Hope that helped to clear that up.

And I would not mix up struct OBJECT and OBJECT. Put it like this:

Code (Text):

typedef struct _OBJECT

{

 struct _OBJECT *child;

} OBJECT;

Click to expand...

Well, you can do that, but it really makes no difference. The other way is accepted also because it's part of the standard.

Keep asking questions. I'll gladly try to answer them!

Dude · Dec 15, 2004

veeery incompleteness

Material Struct - Hacked by Dude
================================
Dword Start; // Always B2 B2 B2 FF
Byte BlueLight;
Byte GreenLight;
Byte RedLight;
void (3 bytes) UnID1;
Byte UnID2; // seems to be 30 in most cases
Byte UnID3; // seems to be 41 in most cases
Byte TexID;
Byte SomethingImportant; // crashes when put to FF
void (3 bytes) UnID4;
Byte unID5; // seems to be Ax (x being a variable)
Byte Spheremap; // 29 = normal; 69 = spheremap
Byte EndOfStruct; // always 94

Lostgame · Dec 18, 2004

Well, is there a way to get textures on to these things in 3DS format? I wanna import the models for Tails into a game with the textures...

Dude · Dec 18, 2004

Not yet. The UVW format is quirky

ICEknight · Dec 18, 2004

Just wondering... Are the Sky Chase low-quality Sonic & Tails models using the same format than the rest of the SA graphics, or an older version?

Dude · Dec 19, 2004

SA uses the oldest 3d graphics in the ninja format anyway. I don't think there's any oddities. Though you should keep in mind that the sky chase models are low poly due to the sheer amount of polygons in that area.

LOst · Dec 19, 2004

Dude said:

SA uses the oldest 3d graphics in the ninja format anyway. I don't think there's any oddities. Though you should keep in mind that the sky chase models are low poly due to the sheer amount of polygons in that area.
Click to expand...

Does that mean optimized models to show less polygons, or a special set of models for the scene?

Dude · Dec 21, 2004

LOst said:

Dude said:

SA uses the oldest 3d graphics in the ninja format anyway. I don't think there's any oddities. Though you should keep in mind that the sky chase models are low poly due to the sheer amount of polygons in that area.
Click to expand...

Does that mean optimized models to show less polygons, or a special set of models for the scene?
Click to expand...

Just for that scene. Dynamic resolution models didn't come in until sa2

LOst · Dec 21, 2004

Dude said:

LOst said:

Dude said:

SA uses the oldest 3d graphics in the ninja format anyway. I don't think there's any oddities. Though you should keep in mind that the sky chase models are low poly due to the sheer amount of polygons in that area.
Click to expand...

Does that mean optimized models to show less polygons, or a special set of models for the scene?
Click to expand...

Just for that scene. Dynamic resolution models didn't come in until sa2
Click to expand...

I don't understand how cameras work in 3-D world space. I have an Direct3D 9 engine that I use, but I have no light, and no 3-D at all. I use special 2-D vertices... Not transformed and not lit I guess. X and Y are screen coordinates. No perspectives.

Issue 1: Sonic Adventure PC and DC model formats

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