Considering the Wavefront obj file format where this syntax fits in the Chomsky hierarchy and why ? I'm also not sure if PEG grammars are being considered in the kind of classification made by Chomsky and if an obj is a real example of a PEG grammar .to formalize this: what kind of grammar and parser I need in order to read an obj file ?
About grammar, Chomsky hierarchy and obj file format
grammar
Depends on how you look at it. The syntax (line per line first few chars show what the line is) is simple and a regular language.The kicker is how to verify the f lines, however when you are parsing you have a turing machine at your disposal and you should just focus on the regular part and step in with the higher level where needed.