Fixed wrong layer height texture updates when using multiple objects

xs/xsp/Print.xsp

@@ -52,6 +52,9 @@ _constant()
     int region_count()
         %code%{ RETVAL = THIS->print()->regions.size(); %};
 
+    int region_volumes_count()
+        %code%{ RETVAL = THIS->region_volumes.size(); %};
+        
     Ref<Print> print();
     Ref<ModelObject> model_object();
     Ref<StaticPrintConfig> config()