I've recently been working with the Motion Calculator Processor for GeoEvent and been wishing I had a simpler version that would just calculate a line instead of all the statistics. The new Timetree Processor I created does exactly that: It creates a line geometry out of a cache of point geometries for a given TRACK_ID. The size of the line is determined by an event window that can be either count based (e.g. the last 5 points) or time based (e.g. the last 5 minutes).
You can download a release of the processor here.

Please note that this processor should be considered BETA since I haven't had a lot of time to test it. If you find an issue please log it in the GitHub project here.