Cesium V2 doesn't support file:/// URLs

[rpte]

I have been using Cesium for unreal and now i can't load the tiles locally with file:/// since it was updated to version 2

[j9liu]

@rpte Can you please provide the following information:

• What version of Unreal engine are you using?
• What exact version of Cesium for Unreal are you using?
• Have you double-checked that the file URL adheres to these formatting conventions?
• If you can share the URL you are trying to load, it makes it easier to check for obvious formatting errors.

[rpte]

What version of Unreal engine are you using? - V5.3.2 What exact version of Cesium for Unreal are you using? V2.2.0 Have you double-checked that the file URL adheres to these formatting conventions? Yes its file:///

[rpte]

Sorry it's loading from local network, like this: file:////server.company.com/Local/3dtiles/tileset.json

On UE5.2 was working fine, but on 5.3 never worked, the same with the newer version 2.2.0 on UE5.2, so we can't use UE5.3 in our projects.

[kring]

Ok, it sounds like you're not loading files locally. You're loading them from a network, via some unspecified protocol. Windows file sharing perhaps?

Here's the full story. Prior to UE 5.3, Unreal itself provided support for file URLs via its HTTP manager. It was provided by libcurl itself, I believe. It only worked on Windows, though. On other platforms, the support was disabled via libcurl compiler options.

Then, in UE 5.3, Epic disabled support for file URLs on Windows as well. Perhaps it was a mistake that it was enabled there (only) in the first place.

So, at that time, we added support for file URLs for Cesium for Unreal itself, so we no longer relied on Unreal's (spotty) support for them. That happened in Cesium for Unreal v2.0.0.

Our support works by extracting the file path from the URL by using uriparser's uriUriStringToWindowsFilenameA or uriUriStringToUnixFilenameA functions (depending on the platform) and then reading the resulting filename using Unreal's FFileHelper::LoadFileToArray. So presumably your network share paths aren't making it through that process for some reason.

Honestly it's mostly just luck that this worked in the first place. You're basically talking about a network share, pretending to be a file, pretending to be a URL. If you want to load a tileset over the network, the best answer is a web server, not a network share. For one thing, requests from a network share cannot benefit from HTTP caching.

But it might be possible to make it work. Try adding an extra slash at the start of the URL. Instead of:

file:////server.company.com/Local/3dtiles/tileset.json

Try this:

file://///server.company.com/Local/3dtiles/tileset.json

It seemed to work ok in my quick test.

[yuxueliyuxl]

v2.1+

[kring]

I don't know what you're saying with that comment, @yuxueliyuxl.

[rpte]

It works with the file://///server.company.com/Local/3dtiles/tileset.json thanks