USD export: ensure edit mode changes are exported

Code authored by Charles Wardlaw.

Reviewed by Bastien, Sybren and makowalski.

Differential Revision: https://developer.blender.org/D15916

source/blender/io/usd/intern/usd_writer_mesh.cc

@@ -18,6 +18,7 @@
 #include "BKE_lib_id.h"
 #include "BKE_material.h"
 #include "BKE_mesh.h"
+#include "BKE_mesh_wrapper.h"
 #include "BKE_modifier.h"
 #include "BKE_object.h"
 
@@ -151,6 +152,8 @@ void USDGenericMeshWriter::write_mesh(HierarchyContext &context, Mesh *mesh)
   write_visibility(context, timecode, usd_mesh);
 
   USDMeshData usd_mesh_data;
+  /* Ensure data exists if currently in edit mode. */
+  BKE_mesh_wrapper_ensure_mdata(mesh);
   get_geometry_data(mesh, usd_mesh_data);
 
   if (usd_export_context_.export_params.use_instancing && context.is_instance()) {