glTF test model (and corresponding texture) licenses:

* Spider (`gltf_spider.gltf`, `gltf_spider.png`):
  * By [archfan7411](https://github.com/archfan7411)
  * Licensed under CC0, public domain "wherever public domain carries fewer rights or legal protections"
* Frog (`gltf_frog.gltf`, `gltf_frog.png`):
  * By [Susybaka1234](https://sketchfab.com/3d-models/african-clawed-frog-v2-c81152c93948480c931c280d18957358)
  * Licensed under CC-BY 4.0
* Snow Man (`gltf_snow_man.gltf`, `gltf_snow_man.png`):
  * By [jordan4ibanez](https://github.com/jordan4ibanez)
  * Licensed under CC0
* Minimal triangle, triangle without indices (`gltf_minimal_triangle.gltf`, `gltf_triangle_without_indices.gltf`)
  * From [the glTF sample model collection](https://github.com/KhronosGroup/glTF-Sample-Models)
  * Licensed under CC0 / public domain