Hi Joerg, so kind of like the snake or Tron lightcycle games where a path is grown leaving a trail behind which you don't want to run into?

Is it required that the closed curve must be made of line segments and not a continuous smooth curve? What if the closed curve is a circle for example?

One thing I noticed is if you put in diagonal lines like this:



Move the diagonal for the start down one step, a quick way to do this is to type 20 and push Enter, that will make a distance constraint active for the next point pick and then you can drag the line down one step:



You now have all the necessary structure to draw the spiral in one single polyline. Before placing the first polyline point type in r20,-20 and push Enter. That will enable an x,y offset to be applied to the next point pick:



From then on straight snap and intersection object snap will give the needed points:







- Michael