# glTF screenshot tests

`npm run test:handles:screenshots` renders the viewer's empty state and every
glTF-Binary model in the pinned Khronos glTF Sample Models revision. The suite
uses headed Chromium on a private Xvfb display and SwiftShader WebGPU at a fixed
1000×720 viewport. It checks the viewer state, browser diagnostics, and a
250×180 downsample against each reviewed reference image.

The first run downloads roughly 215 MB of GLBs into
`~/.cache/yawn/gltf-sample-models`. Set `YAWN_GLTF_FIXTURES` to use another
cache directory, or `YAWN_SCREENSHOT_MODELS=Box,BoomBox` to run a subset.
`YAWN_SCREENSHOT_BASELINES` points at another reference directory (for example
one captured from a known-good commit on a machine whose software renderer does
not match the reviewed references), and `YAWN_SCREENSHOT_SETTLE_MS` (default
1200) is how long the viewer gets to settle after the model loads before the
capture; raise it on slow software renderers.
Failed full-size captures and visual diffs are written to `output/`.

To intentionally replace references after reviewing full-size renders, run:

```sh
UPDATE_SCREENSHOTS=1 npm run test:handles:screenshots
```