I am offering up a new AddOn that traces particles. It appears as a Render engine. To enable it look for it under the Render AddOns. You do not need to select it, it is always on once it has been enabled under User Preferences.
How is this AddOn different from bTrace?
RE:Trace allows you to interactively animate parameters of a trace after generation. It’s control panel appears under the Object context of a RE:Trace object.
How do I install it?
Copy the retrace folder into your AddOns folder.
What is a RE:Trace object?
A RE:Trace object is an object that monitors a particle system and generates/updates curves over time. Each trace curve has a companion taper curve associated with it. The taper is animated by the AddOn to reveal the curve shape over time based upon the particle age.
How does it work?
You create a RE:Trace object using the ‘rename with retrace_ prefix’ button located under the Render context. This button will only appear if the selected object is a mesh. Once a mesh has been converted to a RE:Trace object, additional properties are available under the Object context for that object and shown in the panel image below.
When the frame changes the emitter is examined and the particles are traced. This initial trace can take some time if the particle count is high (say 60 or more, depends upon your machine specs as well). The initial trace will cause a delay in the system, just wait for it to complete (particle end frame determines how long you have to wait). After the trace is complete, you can scrub the timeline and adjust/animate the parameters for the trace as you see fit.
To force a ‘retrace’ generation simply change the particle count then change the frame.
What particle type does it support?
I have tested it with standard particles and boids. I doubt it makes sense to use it for hair.
How do I use it?
Download the ZIP file attached to this post. Install the AddOn and activate it. Open up the example BLEND file contained within the ZIP.