Freeliner is basicaly a free/libre geometric animation software built for live projection mapping. It grew from simple polka dots folowing lines to a feature full "VJing" software. It's current state is a work in progress aiming for a 1.0 release at some point. Freeliner does not aim to be extremely easy to use, but once you understand the workflow the possibilities are endless.
Freeliner is built with Processing. Its easy to set up, offers usefull libraries, well documented, and well maintained.
Freeliner is made to allow external control. The command system allows easy control with flexible arguments. The command 'tw ABC f 2', will set A B and C's fill colormode to mode 2, red. This will be exciting and make more sense once you learn about the workflow. One of the reasons for using Processing is to make hacking more accessible. If you want to make your own colormodes, easingmodes, or even rendermodes, contact me and I will be glad to help.
I am considering a crowdfunding campaign to make a 1.0 release with better documentation. Let me know if this interests you.