ref: 6be6c7a12a4dc890ca67750aa8924f430b2922ea
dir: /spec/
http://paulbourke.net/dataformats/obj https://people.sc.fsu.edu/~jburkardt/data/obj/obj.html https://paulbourke.net/dataformats/mtl/ https://www.loc.gov/preservation/digital/formats/fdd/fdd000508.shtml https://people.computing.clemson.edu/~dhouse/courses/405/docs/brief-obj-file-format.html