MDLX major refactor

[Xeeynamo]

MDLX major refactor

Why

The current Mdlx implementation is fundamentally badly designed.

A MDLX is a file extension that is internally stored as a BAR file. yet the Kh2.Mdlx parser does operate on a file within a MDLX file. It does not make much sense. The Kh2.Mdlx really is a model parser.

Kingdom Hearts II has different model types:

• Legacy: Those are Kingdom Hearts 1 models. KH2 lacks of logic to read them but the identifier is there.
• Background: models that do not represent an entity, like maps
• Skeleton: models that can be animated
• Shadow: models that are flattered on the ground and rendered in their own special way
• Gumi: gummiship models
• Multi: A model that contains more models within it. At the moment I am not aware of any model that falls under this category

Each of them contains their own fields, flags and properties and they share very little in common. Yet our current Kh2.Mdlx tries to do everything. This lead the introduction of Kh2.Mdlx.IsEntity and Kh2.Mdlx.IsMap to circumnavigate the bad design of the parser.

How

Separate each model type into their own class (eg. ModelLegacy, ModelBackground) and let them implement the abstracted class Model.

public abstract class Model
{
    public static Model Read(Stream);
    public void Write(Stream);
    public int GetDrawPolygonCount(IList<byte> displayFlags);
    public IEnumerable<DrawChain> GetDrawChain(IList<byte> displayFlags);
}

Model.Read and Model.Write will parse and write a model file as usual, but internally they will use the appropriate implementation based on the model type.

Model needs to have virtual methods such as GetDrawPolygonCount and GetDrawChain. The method GetDrawChain will be extremely important as it will completely abstract from the draw engine how models are supposed to be rendered. The draw engine will just get a draw chain from the model and render it, unaware of the underlying implementation.

My suggestion is to slowly transition to the new format. Create Model and the underlying model types and wrap them into the existing Mdlx parser. Once Mdlx becomes no more than an empty shell, delete it and expose Model directly.

[osdanova]

Are there examples of said types? There should only be "Skeleton", "Background" and "Multi" afaik.
I agree with the rest.

[Xeeynamo]

Shadow is usually found inside the MDLX in the OBJ folder. I think it's right after the ModelSkeleton?. Gumi seems to be a subset of KH2 logic by its own and apparently the model format is slightly different. Legacy is basically KH1, which shares a lot with KH2.

[kenjiuno]

This is a little nosy though, it shows relation with Skeleton and Shadow. Model is chained.

If you are trying to look up this, visit Kaitai Web IDE, and import the following ksy file as a plain text, and drop a mdlx/map file for parsing.

• https://ide.kaitai.io/
• https://gitlab.com/kenjiuno/khkh_xldM/-/blob/master/Parser/mdlx/bar-model-v2.ksy

[kenjiuno]

entity model p_ex100.mdlx

map model tt03.map

[kenjiuno]

I wrote down public modifier parts of current structure. It is about mdlx parsers.
It is clear that MdlxParser will be better to have Model instead of Mdlx.