Scroll down to the "virtual machine" plugin. It's closed source but there is a PDF that explains how it works, with a nice signal flow graph. You can also get a very good idea of the underlying algorithm by playing around with the parameters.
Also, since someone else is asking about generating squeaking tire sounds, xoxos also has a "friction" VST that does this. There's no audio demo so I made a quick one that emulates tire squeaking:
Edit: and while I'm at it, here's another engine sound demo using "virtual machine" (less interesting than the one on his website, but I put a bit of reverb/ambience on it to make it more realistic):
http://www.xoxos.net/vst/vst.html#models
Scroll down to the "virtual machine" plugin. It's closed source but there is a PDF that explains how it works, with a nice signal flow graph. You can also get a very good idea of the underlying algorithm by playing around with the parameters.
Also, since someone else is asking about generating squeaking tire sounds, xoxos also has a "friction" VST that does this. There's no audio demo so I made a quick one that emulates tire squeaking:
http://007ee821dfb24ea1133d-f5304285da51469c5fdbbb05c1bdfa60...
Edit: and while I'm at it, here's another engine sound demo using "virtual machine" (less interesting than the one on his website, but I put a bit of reverb/ambience on it to make it more realistic):
http://007ee821dfb24ea1133d-f5304285da51469c5fdbbb05c1bdfa60...