Ekg graphic using a buffer

Hi all,
I try to make a ‘like EKG 2d curve’ using a ring buffer.

It’s almost done-but I can’t do it without using polygon to deal with EX9 renderer but it creates artifacts I don’t want.(kind of line loop).

How could I avoid this issue ? I don’t know if I’m clear, but I guess the patch attached would explain my point.
thank in advance.

buffer-forums.v4p (17.4 kB)

like this?

buffer-forums-2.v4p (11.2 kB)

alternatively if you just want it to scroll

buffer-forums-3.v4p (9.6 kB)

yes ! thank you !!