I'm looking for a STEP file parser for ruby that will spit out OBJ files or a model structure similar to OBJ files.
I also have found a make your own parser gem here but not quite sure how to properly set up the parser / lexer rules to use it.
I don't know if this is of any help, but I stumbled across the same problem a year ago. I had to get an IFC parser for C#. Although there are several solutions already, I decided so create my own. Therefore, I had to do the following:
So I reckon you could follow the same path just doing everything in Ruby. I hope this helped a little. Don't hesitate to ask, if you got any more questions.
I use late binding SDAI since I believe early binding (generation of C++/C# classes corresponding to STEP Entities) is not true way. I deal with AP242, AP209, AP238 (some problems were encountered, but I hope to resolve these problem), IFC. So, late binding is better way.