[4.8] Importing FBX and combining meshes not working in promoted branch (commit 7cf4d6f26d74194c2a53fcb8fd41b8e5c6ef02d4)

Development Rendering
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2

I have a potential “fix” or workaround in UStaticMesh* UnFbx::FFbxImporter::ImportStaticMeshAsSingle()

I’ve changed the following:

		int32 NumMaterials = FMath::Min(SortedMaterials.Num(),MaxMaterialIndex+1);
		for (int32 MaterialIndex = 0; MaterialIndex < NumMaterials; ++MaterialIndex)
		{
			FMeshSectionInfo Info = StaticMesh->SectionInfoMap.Get(LODIndex, MaterialIndex);
			int32 Index = StaticMesh->Materials.Find( SortedMaterials[MaterialIndex] );
			if( Index == INDEX_NONE )
			{
				Index = StaticMesh->Materials.Num();
				StaticMesh->Materials.Add(SortedMaterials[MaterialIndex]);
			}

			Info.MaterialIndex = Index;
			StaticMesh->SectionInfoMap.Set(LODIndex, MaterialIndex, Info);
			
		}

To be this:

		int32 NumMaterials = FMath::Min(SortedMaterials.Num(),MaxMaterialIndex+1);
		for (int32 MaterialIndex = 0; MaterialIndex < NumMaterials; ++MaterialIndex)
		{
			FMeshSectionInfo Info = StaticMesh->SectionInfoMap.Get(LODIndex, MaterialIndex);
			int32 Index = StaticMesh->Materials.Find( SortedMaterials[MaterialIndex] );
			if( Index == INDEX_NONE )
			{
				Index = StaticMesh->Materials.Num();
				StaticMesh->Materials.Add(SortedMaterials[MaterialIndex]);
			}
			else
			{
				StaticMesh->Materials.Add( SortedMaterials[ Index ] );
				Index = MaterialIndex;
			}
			Info.MaterialIndex = Index;
			StaticMesh->SectionInfoMap.Set(LODIndex, MaterialIndex, Info);
			
		}

I have a theory that this problem exists for any FBX that has multiple meshes that you are combining and you are NOT importing materials.