An FFGL source that draws four audio meters (a VU, a BBC-style PPM, an LED bargraph and a magic eye), each moving the way its standard says it has to. The VU's damping and natural frequency are solved in code from the two figures in ANSI C16.5 rather than tuned by eye, so the needle overshoots a kick by 1.25 % and settles back because that's what the standard asks for.
This demo runs the plugin's shader in your browser, so it needs JavaScript and WebGL2. The plugin itself, its source and its downloads are on its repository.