Hi Burr, thanks for posting the video, that really helps clear up what you are running into.
That snap line that you are getting that you don't want is called "Axis snap" which is one of the object snaps - it's a feature that makes picked points snap on to the x and y axes of the construction plane similar as if there were lines drawn along them. If you look closely at the object snap text there (the little text label near the mouse), it is saying "On x" when you are near the cplane's x axis line, and "On y" when you are near the cplane's y axis line. When axis snap kicks in it also shows a dashed line on that axis as an additional visual indication that it is activated (a similar kind of line is displayed when straight snap kicks in too).
It can be helpful for other situations when you want to do things aligned to the major grid axis lines, but in this case it is getting in your way.
There are a few different methods you can use to avoid that.
1 - hold down the Alt key which suppresses snapping. If you just hold down Alt you should get much smoother behavior without any snaps kicking in.
2 - turn off "Object snap" by clicking in the bottom toolbar to unhighlight it.
3 - turn off the "Axis" type of object snapping which you can do by the little arrow that pops up when you move your mouse over top of the "Object snap" button on the bottom toolbar.
You don't need to do all of those - just any one of those should solve that problem for you. Probably Alt is the easiest though since it doesn't disturb any settings which you might need to re-activate later.
Rotate works in a kind of planar fashion, after your first pick, any object snaps after that are projected to the plane going through the origin point, that's what causes the behavior that you see there. But it can be useful in some situations to have this kind of projection to snap relative to other objects even though they are on different elevations, that's why those snaps that are off the plane are not just ignored - that enables things like this:
You can see in that situation it was useful to be able to grab a reference point that was projected to the rotation plane, but that's the same thing that is causing you difficulty. There is always the chance for snaps to get in the way, but that's where there are those different mechanisms to turn them off to open things up for free movement.
Does that explain what you are running into and give you some other solutions for it?
Unfortunately it is not so easy to just remove this feature without also removing snapping functionality that can be useful in other situations like shown above.
- Michael
