Actual tested on Monster High: NGS on PC/Wii , Barbie PC, Falling Skies PC, Scooby-Doo 1/2 PC/Wii

Dispaly Texture

Convert 3D model to OBJ

Hunkfile Viewer (.hnk) Torus Games

• Texture information is contained in the Texture Header [0x41150].

• The first two bytes correspond to the texture format.

• Two bytes

Tool

.hnk files (used in games like Monster High: New Ghoul in School) are binary containers storing data records. This script processes these records to reconstruct a complete 3D model in .obj format.

The HNK format is based on data blocks of specific types:

• Type 0x40054 (Vertex Buffer): Stores raw vertex data (XYZ positions, UV coordinates, normals).
• Type 0x20055 (Index Buffer): Stores an index array defining how to connect vertices into triangles.

The main difficulty in the HNK format is that the relationship between vertices and indices is not linear (1:1).

• One large vertex buffer may contain geometry for several model parts (e.g., head, torso, legs).
• Indices inside a single record do not grow indefinitely. Instead, for each new model part (sub-mesh), indices reset to zero (0, 1, 2...).

The script scans index records for so-called restarts. Since each new section (e.g., hair after the face) starts indexing from zero, the script looks for sequences returning to low values (e.g., ..., 4881, 4882, 0, 1, 2). Encountering such a sequence marks the beginning of a new sub-part (Batch).

The OBJ format requires absolute (global) indexing, while HNK uses local indexing. The script applies two levels of offsets:

1. Local Block Offset: Used to navigate inside a single large vertex record. If Part 1 uses 1000 vertices, Part 2 (which starts indexing from 0) must have an offset of +1000 added to point to the correct data within the same buffer.
2. Global OBJ Offset: Used to combine multiple HNK records. If the first record (e.g., body) had 5000 vertices, indices from the second record (e.g., hair) must be shifted by +5000 to point to unique line numbers in the OBJ file.

HNK files do not have a fixed vertex size. The script dynamically detects the structure size (e.g., 32, 40, or 48 bytes) by analyzing separators and data patterns. This allows correct reading of XYZ positions and texture coordinates (UV) regardless of model complexity.

For each Batch, the script reads indices in groups of three, creating face definitions in the format: f v1/uv1 v2/uv2 v3/uv3 UV coordinates are automatically flipped on the Y-axis (1.0 - v), which is standard when converting from Direct3D systems (used by the game) to the OpenGL/OBJ standard.

• Parser: struct.unpack("<H", ...) for indices (16-bit unsigned short).
• Vertex Data: struct.unpack("<3f", ...) for positions (3x 32-bit float).
• UV Data: Offset by a variable uv_offset inside the vertex structure.
• Part separators: Pattern [0, 1] after values above a certain threshold, or optionally a 0xFFFF separator.

3D Model Extractor

Tested on Monster High NGiS PC, Barbie PC, Scooby Doo 1/2 PC.

• Texture information is contained in the Texture Header PC [0x41056] , Wii [0x41033].

PC

Wii

• Two bytes

Format type = 0x18 0x00 0x00 0x00 offset: 15 4 bytes

Name count offset: 6 2 bytes

size name block offset 9 2 bytes

after name block padding 00 - offset 2A 2 byte width 2 byte height skip meta - offset 2D

after name block padding 00 - offset 2A 2 byte width 2 byte height skip meta - offset 2D

ect.

block texture data - 0x201034 / 0x201035

• download repo
• run hunkfile_viewer.py

https://github.com/desuex/hunkfile - HNK Structure/Table