Currently use QC to make custom layers for Bonix TV - a vision mixing kind of application for OS X with a kind of QC stack of layers, each layer being a composition with published ports and some protocols for data types. Also generate sports graphics and twitter feeds and so on for video score boards at large sporting venues.
Spent a few years learning Quartz Composer as my way back into coding from a decade away doing design related work. Film, graphics, studied Architecture for a few years and got involved in publishing then film. Now moving into front side web development. Hope to get into app dev with Vuo and rapid app prototyping.
OFX is an open standard for compositing software. BlackMagic Design's DaVinci grading/compositing software now has a couple of pretty advanced non-linear editing modes, and there's a free version of DaVinci that anybody can use.
I used Adobe Premier Pro and After Effects and would really like to be able to export plugins for those Apps too, but perhaps OXF is more accessible to the community given free version of DaVinci Studio. For plugin developers I expect that the Adobe plugin market is bigger than OFX so I'll FR that to and see what gets more votes.
here's a page of info about comping/editing tools that support the OFX plugin API. And OFX plugins and more.
this is a pretty standard thing to do in motion graphics and comping software. drawing a line starting at point A going to point B, with variable inputs for speed of movement of leading point of the line, length of the full opacity line, length l of the trailing edge of the line that gets opacity applied.