pgraph: fix regression in 89236ac1360e5f0249d425e61d537deef40e71c3

panda/src/pgraph/billboardEffect.cxx

@@ -374,6 +374,6 @@ fillin(DatagramIterator &scan, BamReader *manager) {
 
   if (manager->get_file_minor_ver() >= 43) {
     _look_at.fillin(scan, manager);
-    _fixed_depth = scan.get_stdfloat();
+    _fixed_depth = scan.get_bool();
   }
 }