resolves #27

and fixes caching

app/properties.py

@@ -360,6 +360,8 @@ def prebuilt(content, file_format, lod):
     )
     if filename:
         filename = filename[0].split("\\\\")[-1].lower().split(".")[0]
+        if "/" in filename:
+            filename = filename.split("/")[-1].lower()
     else:
         return f"No filename for LOT {content.lot}"
 
@@ -372,6 +374,7 @@ def prebuilt(content, file_format, lod):
 
     elif file_format in ["obj", "mtl"]:
         cache = pathlib.Path(f'app/cache/BrickModels/{filename}.lod{lod}.{file_format}')
+        if not cache.is_file():
             cache.parent.mkdir(parents=True, exist_ok=True)
             try:
                 ldd.main(str(lxfml.as_posix()), str(cache.with_suffix("").as_posix()), lod)  # convert to OBJ