The compilers of Visual TrueType are now open sourced and shared at the following site. The included command line tool that uses the compilers is vttcompile and similar to the vttshell tool included with VTT download.
The project includes build action for Windows. There is no dependency on ‘window.h’ in the code but there is still work to be done to port the code for MacOS or Linux.
There are no unit tests in the project yet.
I have created a number of issues to track needed enhancements and bug fixes.