Use of the environmentmap attribute to set a custom
image-based light (IBL) resource. Note that while the resource may be an
image in any format, the dynamic range requirements for an IBL mean that
it is strongly recommended to use a raw, high-dynamic range (HDR) format
like the Radiance RGBE .hdr format, or the OpenEXR
.exr format. Resources are assumed to be presented in the
equirectangular projection.
<model environmentmap="night.hdr" alt="a teapot in a dark environment">
<source src="./teapot.usdz" type="model/vnd.usdz+zip" />
<source src="./teapot.glb" type="model/gltf-binary" />
<img src="./teapot-fallback-ibl.jpg" alt="An image of a model of a teapot lit by a dark environment" >
</model>