Ninja Model Formats

The following information delves into the model formats used in games that utilize the Ninja SDK, such as Sonic Adventure and Sonic Adventure 2. While the contents of the raw data vary between formats, they all share the same OBJECT container.

OBJECT Container

When viewed in code, an OBJECT container will have the following arrangement. Despite the existence of this container, it may often not be used as a reference point for calling model data within the specified game. This is determined on a case-by-case basis, and all models exported by SA Tools and SAIO will include it by default.

Offset (Hex)	Type	Description
0	INT32	Model flags
4	Pointer	Model data. This points to the main container for the specified model. This value can also be null to establish an empty node in a hierarchy.
8	Float(3)	Position
14	INT32(3)	Rotation
20	Float(3)	Scale
2C	Pointer	Child OBJECT.
30	Pointer	Sibling OBJECT.
34	INT32	Quaternion value. Some games may not account for this space being present within their data, so its inclusion may cause issues. Sonic Adventure 2 (PC) incorporates this space for models in the game's code but not Sonic Adventure, for example. This portion is not included by default in SA Tools Hub/SAIO exports except for "Ginja" models.

Basic Models

Primarily used in Sonic Adventure, Basic models are the first model type developed for Ninja. Skinning is not normally possible with this format, but a specialized variant has been developed for use with Sonic Adventure DX (2004) with the "Weighted Characters" mod.

Sonic Adventure 2 utilizes this format for collisions and death barriers, never in a visible sense.

Sonic Adventure DX introduces a variation of Basic models - referred to as "Basic+" or "BasicDX" - and is the primary format of that game.

Offset (Hex)	Type	Description
0	Pointer	Vertex data
4	Pointer	Normals data
8	INT32	Vertex/Normal count
C	Pointer	Mesh data
10	Pointer	Material data
14	INT16	Mesh count
16	INT16	Material count
18	Float(3)	Model center. This is used for bounds calculation
24	Float	Model radius. This is used for bounds calculation
28	INT32	Used in "Basic+"/"BasicDX" model data only.

Chunk Models

Chunk models are the premier format used in Sonic Adventure 2. This format supports skinning by default.

Sonic Adventure DX incorporates this model format for specific parts of the game, notably the Chao models and the Cream the Rabbit cameos.

Offset (Hex)	Type	Description
0	Pointer	Vertex data
4	Pointer	Polygon data
8	Float(3)	Model center. This is used for bounds calculation
14	Float	Model radius. This is used for bounds calculation

"Ginja" (GC) Models

This format was introduced in Sonic Adventure 2 Battle and further refined in Billy Hatcher and the Giant Egg. Utilizing a combination of Ninja and Nintendo's systems, "Ginja" models (a portmanteau of "GameCube" and "Ninja") are often Chunk models converted to make use of newer technologies. Sonic Adventure 2 Battle's implementation does not have skinning support, which was addressed in Billy Hatcher.

Currently, neither SA Tools Hub nor SAIO has the ability to read or export "Ginja" models with skinning.

Offset (Hex)	Type	Description
0	Pointer	Vertex data
4	Pointer	Weight data
8	Pointer	Opaque polygon data
C	Pointer	Translucent polygon data
10	INT16	Opaque polygon data count
12	INT16	Translucent polygon data count
14	Float(3)	Model center. This is used for bounds calculation
20	Float	Model radius. This is used for bounds calculation

Sonic Adventure Information

General Information		File Formats • Model Formats • Level List • Texture Files • Game Builds • CAM & SET Files
Character Information		Character List • Actions • Animation Lists • Faces
Sound Information	General	Voice List • Music Files
	Sound Effects	Stage Sounds • Stage Background Sounds
Other		Cutscene List • Fish List