Mesh picking on simplified mesh picks the wrong mesh

[Evgeni_Popov]

The problem may be that meshes from glTF files are right handed.

See this answer (the overrideMaterialSideOrientation part):

Why are the simplified mesh surface normals all flipped

The doc about mesh simplification is saying that artefacts with uv mapping can occur when using optimizeIndices. In that case, it suggests to use the optimizeMesh option instead. Also, as meshes are coming from a .gltf/glb file, the mesh.overrideMaterialSideOrientation property should be copied over the simplified meshes. Here’s a fixed PG: