# Sponza example

Loads the Sponza atrium as a `.cmesh` + one albedo `.ctex` and renders
it via ray tracing on both Vulkan (native) and WebGPU (wasm). Same
`main.cpp`, `#ifdef CRAFTER_GRAPHICS_WINDOW_DOM` selects the backend.

## What this example proves

- `.cmesh` and `.ctex` decompression round-trip on both backends
  (GPU via `VK_EXT_memory_decompression` on Vulkan, CPU via
  `Compression::DecompressCPU` on WebGPU).
- A single texture binding flowing from `Image2D<RGBA8>` through the
  RT pipeline's closest-hit on both backends. The closest-hit samples
  at the barycentric attribs as UVs — proof-of-binding, not visually
  accurate. Per-vertex UV interpolation is the next step.

## Asset fetch

`project.cpp` calls `Crafter::GitFetch(...)` on
[https://github.com/jimmiebergmann/Sponza](https://github.com/jimmiebergmann/Sponza)
(pinned to commit `222338979d32f4f4818466291bdbc29f192b86ba`). The
clone lands in the per-user crafter-build cache; first build pulls
~280 MB once, subsequent builds reuse it.

`cfg.assets` then picks two files out of that clone:

| Source                                  | Compressed output       |
|-----------------------------------------|-------------------------|
| `sponza.obj`                            | `sponza.cmesh`          |
| `textures/sponza_arch_diff.tga`         | `sponza_arch_diff.ctex` |

Both land flat in the example's bin directory.

## Building

```
crafter build                          # native Vulkan
crafter build --target=wasm32-wasip1   # WebGPU / wasm
```

## License & attribution

Sponza geometry, materials, and textures are licensed under
[CC BY 3.0](https://creativecommons.org/licenses/by/3.0/).

- **Original model:** Frank Meinl, Crytek (2010).
- **OBJ packaging / cleanup:** Morgan McGuire, McGuire Computer
  Graphics Archive — https://casual-effects.com/data.
- **GitHub mirror used here:** Jimmie Bergmann's roof-material fixup —
  https://github.com/jimmiebergmann/Sponza.

When redistributing builds of this example that bundle the compressed
Sponza outputs (`*.cmesh`, `*.ctex`), the CC BY 3.0 attribution
requirement applies. Quoting the original credit somewhere visible to
end users (about-screen, credits page, etc.) is enough.

The Crafter.Graphics library code itself is LGPL-3.0; the two
licenses are compatible for data + code distribution.