A reason that they can be choppy in 0.5 zoom is because the points are integers while 0.5 is not. When I programmed the trails I didn't think I would make a zoom function.
Do you mean the trails or the actual movement of the bodies? The trails are just lists of points that are connected by the world (not the best solution and I probably will do something about that).
2016/8/1
Gravity Sim
2016/7/26
Planets
2016/7/25
Perspective 3D
2016/7/25
Platformer
2016/7/23
Platformer
2016/7/13
Drum Kit
2016/7/12
Planets
2016/7/12
Planets
2016/7/12
Koch Snowflake