poor performance with some gltf files

[makc]

so this file here has some 120K tris and 3 x 2K textures, however when I drop it into 3js editor fps goes out the window. I get much better performance in https://sandbox.babylonjs.com/ with the same model.

@donmccurdy could it be related to the fact that, for some reason, 3js loader duplicates the textures for each map in every material across the model? here, we have 4 identical materials with 5 maps, 3 of them being same texture, but 3js creates 20 textures for this:

glb file in zip below:
three_js_problem_model.glb.zip

[mrdoob]

Does performance goes out of the window when dropping it in https://model-viewer-tester.glitch.me/?

[donmccurdy]

There's a minor issue in this file where each texture defines a KHR_texture_transform extension, containing only a redundant texCoord index:

"texCoord": 0,
"extensions": {
  "KHR_texture_transform": {
    "texCoord": 0
  }
}

Normally that extension is supposed to define a transform (offset, rotation, scale) and so we preemptively clone the texture, but in this case the extension is doing nothing. @makc would you be able to report this to the babylon.js 3DS Max exporter with the source file if possible? It'd be great if they could omit this extension where it isn't actually used.

In the meantime #21821 should work around the issue here.

[makc]

@mrdoob it does (
@donmccurdy nice, thanks!