Hi ed,

> Recently I've been many times in the same situation: I have 2
> or more curves and I want to draw something (a polyline, a
> circle or an interpolated curve) that touch those curves but with
> all the points sharing a single plane.

Like Mike mentions above, the View > CPlane tool can be good for this situation.

The key thing that helps is that there is a intersection object snap available where a curve intersects the construction plane. So once you place the cplane you should then have snap points at all these juncture points that you were interested in, you should not need to do the extra step of actually cutting all the objects.

The snap tag will read "CPlane Int" when that object snap is active.


> What do you think about this feature?: Making two
> construction lines that starts on the same point makes a
> temporary cplane. I think this could be useful in many situations
> not just the one I described above.

I've thought about that one before, and that could be possible to align things that are looking for a surface normal direction like drawing a circle but probably not for generating intersection object snaps like placing a full cplane will give you.

But also I worry about aligning normal directions automatically too much though, it can potentially make for bad results if the thing you really wanted was a circle that had its origin at that particular intersection location but was still aligned to the cplane.

Here's an example of that - here I use one construction line to drop downwards in z and the other to come horizontally and then draw a circle. But if it the 2 crossed lines formed a temporary cplane you would not be able to get this same circle anymore:



It's kind of safer to rely on setting a cplane to make that kind of stuff, since placing the cplane is more controllable with more options in it.

- Michael