Hi DesuDeus - you can use construction lines to get that kind of a line drawn more quickly.
If you haven't checked out construction lines yet, you're going to probably like them a lot. They enable creating a lot of precision placement things and by default they automatically go away after you have finished the command so there is no cleanup step like you have when creating a regular temporary line.
To make a construction line, when you go to pick a point instead of clicking the point, you press and keep the mouse button held down and drag it away. That creates a Construction line which is a kind of guideline that helps get you a variety of different snaps. When you release the mouse button the construction line will be formed from the start point to that released point.
Among the several things it helps with is to draw a line that is balanced around a particular midpoint.
Here's an example of how it works:
So notice there that when you create a construction line from the initial drag point to the place where you release the mouse, the reflected endpoint is also available as a snap, so that helps you to draw things that are halfway positioned around a midpoint.
One big benefit of this mechanism is that it works on any kind of point pick and not just as a special option for only the line command.
For example here I'm using it with Rectangle 3pts, to draw a square that is positioned with a midpoint of its edge in the same way:
> a 3 points line, wich can be transformed to an arc just by
> moving the center point)
You can also use construction lines to help you draw an arc as well - here I'm showing it using Arc 3 pts:
There are all kinds of other things you can do with construction lines too, like get a snap point midway between any 2 existing points, set up incremental snaps between 2 points (like 1/3 increments), capture a distance or direction between 2 points and relocate the line somewhere else to use it, do extensions, alignments, etc... Some more information on it is available here:
http://moi3d.com/1.0/docs/moi_command_reference10.htm#constructionlines
- Michael
