Join the trails of flock agents

Hello everyone! I have a flocking agents algorithm with Quelea and I want to join the trails of the moving agents with bezier curves or meshes to see the forms that emerge from the moving agents. All I have managed is to construct polylines joining the postiions of the particles. What I have in mind is something like in the processing sketch I'm attaching (Flocking_BeziersBetweenTails) ! Thank you :) 

I want it to look like this from the Processing code:

Flocking_BeziersBetweenTails.pde