I got the following patch but Im getting a strange tails on the boids. The same thing if im using jit.gl.handle to move my boids on the screen with the mouse. I illustrate the problem on the attached images.
A couple of missing objects in that patch here: xray.jit.boidsrender: No such object. jit.boids2d: No such object. In any case the 'problem' appears to lie in that the erase colour value in [jit.gl.render boids ] is leaving some of the preceding frame(s) in place - try @erase_color 0 0 0 1 instead to fully erase the previous frames.