Introduction to 3D Design - Autodesk AutoCAD 2013 Practical 3D Drafting and Design - page 26

3D polylines
Polylines created with the PLINE command are 2D, not allowing for vertices with dif-
ferent Z coordinates. These polylines are designed by lightweight polylines. But what
if a single object is needed to be composed by segments whose endpoints have dif-
ferent Z coordinates?
The answer is to create 3D polylines. Three processes are available:
• 3DPOLY : This command (alias 3P ) creates 3D polylines from the start. It
works like the LINE command, but the result is a single object.
• JOIN : This command (alias J ) creates 3D polylines from a contiguous se-
quence of lines with shared endpoints. It is enough that one endpoint of
a line is out of the plane for a 3D polyline to be created.
• PEDIT : The same command (alias PE ) used for the creation of 2D poly-
lines from lines and arcs can also be applied to join lines to a 3D polyline.
The first object must already be a 3D polyline.
Note
Starting with version 2012, the best way to apply the JOIN command is to select
all the line segments at the first command prompt, without specifying a source
object. Depending on the type of selected objects and their positions, the most
suitable object is automatically created.
And in what situations may we have utility for 3D polylines?
3D polylines are particularly useful to measure objects that develop in different dir-
ections, such as piping or wiring, and to define paths for other 3D objects such as
piping. The creation of 3D solids and surfaces from linear objects is the subject of
Chapter 4 , Creating Solids and Surfaces from 2D .