LDrawLoader: Further improve smooth normal generation performance

[gkjohnson]

Merge #22228 first

Description

• Adjust the bookkeeping of faces to retain whether the original face was a quad or triangle and change normal smoothing and geometry generation accordingly.
• Rename scope.triangles array to scope.faces

With this change the total load time for the AT-ST model comes down from ~21 seconds to ~15 seconds compared to #22228.

There's a normal smoothing issue I found (not new) that I'll fix in another PR and I'll add preloadMaterials and setPartsLibraryPath functions so the loader is easier to use with the full LDraw parts library.

cc @yomboprime

[yomboprime]

...and I'll add preloadMaterials and setPartsLibraryPath functions so the loader is easier to use with the full LDraw parts library.

Is it not sufficient with the current setPath()? It does exactly that (establishes the path to the library)

[gkjohnson]

Is it not sufficient with the current setPath()? It does exactly that (establishes the path to the library)

It does but it seems like a common case that the model you want to load would be saved in a different location from from the the canonical parts library. For example you currently can't load a model if your parts are stored at /path/to/parts/library/ and models at /path/to/models/ even if you pass the absolute path in for the model URL (which is maybe something else that should be fixed across loaders, too?) so I'm proposing the following:

new LDrawLoader()
  .setPath( '/path/to/models/' )
  .setPartsLibraryPath( '/path/to/parts/library/' )
  .load( 'my-model.mpd', result => {} )

[yomboprime]

Okay, I see it fine.

[mrdoob]

Thanks!

[mrdoob]

Merge #22228 first

Ops! Missed that. Lets see if I can fix this...

[mrdoob]

Seems like I can't... I reverted this PR and merged #22228.
I tried cherry-picking this PR again but I'm getting conflicts. Sorry... 😅

[gkjohnson]

Heh sorry I should have marked as draft 😅

Here's a replacement PR: #22247