Importing from data: URIs / MIME type inference

[antonok-edm]

There isn't an obvious way to import a 3D model directly from a data: URI. I tried using LoadModelFromUrlList with the data: URI, but it failed with No importable file found.

After some experimentation, I was able to create it by manually constructing a File object, although it wasn't pretty:

const dataUrl = 'data:model/stl;base64,...';

const dataBlob = await fetch(dataUrl).then(res => res.blob());
const dataFile = new File([dataBlob], 'foo.stl');  // must manually provide correct extension

viewer.LoadModelFromFileList([dataFile]);

Some brief digging through the code suggests that the filename's extension is used to determine whether or not a model format is supported. That approach is incompatible here because data: URIs do not have filenames.

Perhaps also of interest; URL fetch responses may offer a supported MIME type despite the URL's path having a different extension, or no extension at all. I imagine it'd be useful to support cases like that as well.