Algodoo

Yup, good job! That is very similar to what I was working on (you just beat me to it! ). Another limitation that I'm working on is the ability to place the tracer anywhere on another geometry. Currently, it is fixed at one particular pos, and you cannot easily relocate it without modifying the code. I have an idea how to fix that, but maybe you can think of a way that's simpler and/or more efficient.

You could use the green bar pos and angle properties along with the tracer relPoint property to determine the actual tracer position. The tracer can store its color, size, fadeTime, and relPoint properties (without using Scene.my. variables) on the green bar before being killed. The new tracer can be initialized using properties stored on the green bar. Any subsequent tracer changes can be stored on the green bar. The only Scene.my. variable required would be Scene.my.clearTracer.

"The tracer can store its color, size, fadeTime, and relPoint properties (without using Scene.my. variables) on the green bar before being killed."

That's the part I'm not sure how to do. I believe it uses "readable" to get the property values, but I do not know the exact syntax. Could you help me out with that?

Look at the hinge code in the original Gumby scene.

Excellent! Thanks

EDIT: Please take a look at my post in the Forum:

scene.entityByGeomID and other mysteries

That's AWESOME! Thanks VERY much!

You must be kilinich's protégé.