0 Polyline and Edit Polyline

“Polyline”and “Edit Polyline”

The polyline is a line type with which we can draw, but has different characteristics and functions more advanced than the normal line that we have already used.
We initiate this command by pressing the Polyline   and draw a line with some segments by clicking repeatedly on the screen with the left mouse button, at random, then do click with the right to end the polyline.

The fundamental difference between a line and a polyline drawn in this way is that the polyline is identified as a single object, in fact, if you click a segment, we see that it is highlighted and selected the entire polyline while in the case of each normal line segments may be selected independently.
Figures such as rectangle, polygon or circle drawn by the relevant commands that we have seen, therefore, correspond to the closed polylines as they also are identified as individual objects.
Through the command "edit polyline"  , which is on "MODIFY II" toolbar, we can assign to a polyline thickness whereby it will be displayed on the screen.
We can smooth the top, transforming it into what is called a "spline" and vice versa.
We can turn a normal line to polyline and add it to other segments which have the vertices coincident.
We see the first case:
After drawing a polyline segments activate the command "edit polyline" .
On the "command line" appears:
"Select polyline or [Multiple]"
Then select the polyline.
(Typing "m" for the [Multiple], then press enter, you can select multiple polylines if any).
At this point we can choose various options, as indicated on the command line, by typing out their letters of abbreviation.
Then type W for width and press enter.
Then type in the value of desired width, e.g. 5 and press Enter.
The polyline will be expanded, the command however, unlike other will not be concluded, in fact on the command line options are still present.
To close it, we must press "Enter" or the right mouse button.
Instead, type S for spline and press Enter, the vertices of the polyline will be getting a curved spline.
Now type D for decurve and Enter, the polyline is as good as before.
Pressing Enter again will exit the command.

If instead we have a series of consecutive segments, or a closed figure, made from the normal line, with this command you can turn them and put them together in a polyline.
Activate the command  and select one of the segments.
Since it is not a polyline, AutoCAD asks us if we want convert it (see the command line), press Enter to confirm, at this point all options will appear as before.
Now type J to join and select all other segments, or arcs, which have the vertices coincident, selecting them individually or all together with one or more selection boxes, then press enter twice to exit the command.
All selected lines will be merged and turned into one polyline.
To do these, lines must have a vertex coincident, i.e. they must touch, if not even a very short, will not be join together.

Let's see how this feature could be useful.
Suppose we have the plan of a room, which may be rectangular in shape but also more elaborate, on which we must draw a false ceiling with a pattern that follows the perimeter of the room.
We can start to make the offset of each wall to the inside, but then we should cut or join all the lines intersect.
If, however, join in a polyline walls of the plant as a result we can perform with just a few of the figures offset concentric and equidistant from the perimeter, without then having to make other interventions blending.

What we have seen are the options for the polyline used more frequently, especially that for the "width" and the "join" features.