Hello Hai Pham and welcome to the LAVA forums!
I used to work with 3D printers so I am pretty familiar with STL files and gcode. Unfortunately LabVIEW does not natively support these files. Interpreting STl files and generating tools paths in LabVIEW would be quite difficult. Instead, I would use another program to generate gcode from STL files. Then you can focus on parsing the common set of gcode instructions in LabVIEW. I have seen several people ask about this on the NI forums but I have never seen a solution. Perhaps the member here will send their solition if you ask nicely. Otherwise, you may have to write this code yourself if you can't find anything online.
Best of luck creating your FDM printer!