Algodoo

Move the script from onKey to postStep, then it will work!

Good call, Xray. It looks like _mp constantly updates when in onKey but not when in postStep. Also, the code only needs to be in one object (the spring), not three. Use the Alt key to select just one object.

That's a good point about selecting springs. Some people may not realize that when you select a spring in the usual way that you select other objects, you will actually select three objects (the spring and the two end points). If you want to select only the spring, you must press and hold the Alt key while clicking on the spring.

In this particular case, Fruitmonger selected all three objects because I see that the script was written to all three objects (which is redundant and ill-advised). Therefore, he should delete the code that was written to both end points, and then move the code in the spring.

Thanks guys, I'll give all that a try. I can't believe I forgot to hit alt when selecting the spring.