# 3D Model Attribution

## BMW M4 Competition M Package

- **Author:** [𝙎𝙍𝙏 𝙋𝙚𝙧𝙛𝙤𝙢𝙖𝙣𝙘𝙚™](https://sketchfab.com/TheRealSRT)
- **Source:** [BMW M4 Competition M Package on Sketchfab](https://sketchfab.com/3d-models/bmw-m4-competition-m-package-5c0a2dafb1ad408d9fc9eeef9aee531b)
- **License:** [Creative Commons Attribution 4.0 International (CC BY 4.0)](http://creativecommons.org/licenses/by/4.0/)
- **Files:** `bmw-m4.glb`, `bmw-m4.optimized.glb`, `bmw-m4.web.glb`
- **Changes:** The optimized derivative uses Meshopt geometry compression and WebP texture compression, with textures limited to 1024 px. Geometry simplification is disabled.
- **Web derivative:** The runtime derivative additionally removes four cabin/engine meshes hidden in the closed-car configurator, removes three textures replaced by runtime materials, and limits remaining textures to 512 px. Geometry simplification remains disabled.

The source GLB embeds the following attribution metadata in `asset.extras`:

```text
author: 𝙎𝙍𝙏 𝙋𝙚𝙧𝙛𝙤𝙢𝙖𝙣𝙘𝙚™ (https://sketchfab.com/TheRealSRT)
license: CC-BY-4.0 (http://creativecommons.org/licenses/by/4.0/)
source: https://sketchfab.com/3d-models/bmw-m4-competition-m-package-5c0a2dafb1ad408d9fc9eeef9aee531b
title: BMW M4 Competition M Package
```

Both derivative GLBs retain this embedded `asset.extras` attribution.

## Asset Integrity

| File | Size (bytes) | SHA-256 |
| --- | ---: | --- |
| `bmw-m4.glb` | 22,739,084 | `913ac951ba2645777c91393b86aed2def2433a807e57e626b203908aa474b8fb` |
| `bmw-m4.optimized.glb` | 5,790,016 | `9379539798ba1a3d79ebe52d52469778af6334e8261e834536d5cd4726c720a5` |
| `bmw-m4.web.glb` | 3,886,832 | `1a072ff0aee180b1c13d60c0ae47c93e7c151240c532b60101449a651531b3e1` |

Regenerate the derivative without overwriting the source file:

```bash
./scripts/optimize-model.sh \
  public/models/bmw-m4.glb \
  public/models/bmw-m4.optimized.glb
```

Regenerate the web runtime derivative:

```bash
./scripts/build-web-model.sh \
  public/models/bmw-m4.glb \
  /tmp/bmw-m4.web.glb
```

Template changes: midnight-blue clearcoat paint, restored carbon weave texture, separate finishes for the grille, glazing and wheels, red brake calipers and emissive running lights. The original geometry and emblems are retained.
Used in this template: assets/models/bmw-m4.glb, based on the optimized derivative above.