Hi eric,

> I have been trying to get my head around 'loft, sweep and
> extrude', their differences and similarities and sure get some
> strange shapes I don't expect sometimes.

When you run across the strange ones, if you can post them here I could probably explain what is going wrong.

For sweep the main thing that can be confusing is whether "auto-place" mode is being used or not.

Auto-place mode lets you draw a sweep profile flat on the regular drawing plane, and then will move and rotate it into place perpendicular to the rail curve for you, before starting to drag the profile along the rail.

Auto-place mode is implicitly turned on or off depending on whether the profile curve is inside the bounding box around the rail curve or outside of that box.

So one thing that is easy to do is to draw a flat profile curve but not have it quite far enough off to the side so that it is outside of the rail's bounding box. That will mean auto-place will not be turned on, and your curve will be taken from exactly where it currently stands and then dragged along the rail curve.

I am planning on making some more explicit control over turning auto-place on or off which I think should help a bit.

That auto-place mode is also covered on that 6-legged pod video tutorial: http://moi3d.com/1.0/docs/pod.htm

- Michael