kivy-garden/garden.particlesystem — pull request #3 by lexelby (2013-07-23 02:06:46+00:00)
Title: added friction parameter

Set to a small floating point number for natural-feeling "air friction".
With gravity, a "terminal velocity" naturally emerges.

I tried to make the change as computationally minimal as possible -- just two subtractions and two multiplies per frame. I also made the default value of friction 0, which would have no effect, and didn't add it to the XML parsing so that PEX format compatibility is retained. I understand if you don't want to pull though :)