Obtain Base Url for Texture Requests within Reality Tile Loader

[andremig-bentley]

Currently, there is a bug attaching a 3dTiles tileset to the itwin viewer using attachRealityModel where if that model has textures, and the tileset has relative URIs for those textures, they will not be requested. This is because the base url for those requests was not being passed along to the gltf reader, and so an attempt to resolve the images for these textures would fail. This PR addresses that issue by creating the new optional baseUrl parameter passed down through the creation of the RealityTileTree. baseUrl is created using the new getTilesetUrlFromTilesetUrlImpl in RealityDataSource, which obtains the tileset url from a source which is an instance of RealityDataSourceTilesetUrlImpl. In RealityTileLoader.ts, the url is checked to determine if it's a valid url, and if so, it is passed in to the creation of the GltfReaderProps, and therefore, to the gltf reader.

[aruniverse]

does this need to be backported to 4.10? or can it go in 4.11?

[aruniverse]

all of this seems very fragile,
please add unit test for these

[markschlosseratbentley]

@aruniverse does the added unit test suffice?

[andremig-bentley]

does this need to be backported to 4.10? or can it go in 4.11?

No backport is needed, 4.11 is fine, thanks.

[andremig-bentley]

An update on this PR - Due to the fragility of the tree id parsing method, the methods of obtaining the base url for this PR have changed. Now, all tree id parsing has been removed, and instead, the id has been passed down through the creation of the RealityTileTree as the new optional member rdSourceId. By passing down the id directly, we avoid any possible issues that would come with parsing and avoid errors that might have been caused by unexpected aspects of the tree id.

Tests have been added to a new file, RealityTileLoader.test.ts, which test the creation of GltfReaderProps including or not including a base url as expected. This new test file includes a lot of set up code from GltfReader.test.ts which was necessary to successfully create GltfReaderProps. In my opinion, these tests make more sense being in their own file rather than being in GltfReader.test.ts, but they can be moved/changed if necessary.

Finally, we were able to test the case where a base url is passed in to the gltf reader for a tileset with full texture urls - the case discussed in my comment above. The texture requests worked as expected with no issues, so that edge case is a non-issue.

[pmconne]

Delete this, add an optional method on the RealityDataSource interface, and implement it in RealityDataSourceTilesetUrlImpl. That will allow any other implementations of RealityDataSource to implement it themselves if they so choose.

[pmconne]

These tests don't prove much. A much more valuable test would confirm that you successfully resolve a resource inside the glTF with a relative URL where prior to your change you would have failed to do so.