fix(assets): make vehicle kit verification standalone

blender/tools/split_lowpoly_cars.py

@@ -1,11 +1,14 @@
 #!/usr/bin/env python3
 """Split the downloaded LowPoly Cars Blend into a browsable, reusable asset kit.
 
-Run through Blender because the source Blend is not safe to open in the sandbox:
+Run through Blender because an imported source Blend is not safe to open in the sandbox:
   blender --factory-startup --background --python blender/tools/split_lowpoly_cars.py -- \
-    --source /Users/que01/Downloads/011.+LowPoly_Cars_01_blend.blend \
-    --textures /Users/que01/Downloads/textures111 \
+    --source /path/to/source-cars.blend \
+    --textures /path/to/source-textures \
     --output assets/models/custom/lowpoly_cars
+
+This is an optional re-import tool. Completed asset kits do not read the source
+Blend during area builds or Cesium preview generation.
 """
 
 import json
@@ -14,10 +17,6 @@ import os
 import shutil
 import sys
 
-import bpy
-from mathutils import Matrix, Vector
-
-
 TEXTURE_NAME = "color_512x512.jpg"
 PREVIEW_SIZE = 640
 CESIUM_ALBEDO_GAIN = 2.6
@@ -276,6 +275,12 @@ def main():
     if "verify" in args:
         verify(os.path.abspath(args["verify"]))
         return
+    # Keep verification independent from Blender so the checked-in kit can be
+    # validated after the original source has been removed.
+    global bpy, Matrix, Vector
+    import bpy
+    from mathutils import Matrix, Vector
+
     source = os.path.abspath(args.get("source", ""))
     texture_dir = os.path.abspath(args.get("textures", ""))
     output = os.path.abspath(args.get("output", ""))