By Dennis Collin
Polylines are very useful objects in drawings as they can provide useful information like perimeter length and areas. They can also be used to define the extents of hatch pattern infills and have graphical properties applied such as linewidths. This information can easily be lost when exploding these entities when performing edits and if length or area parameters are linked to a text field the associativity is lost. The trim option whilst a better approach to modifying polylines can still break the link between fields and polylines properties if elements are re-joined back to polylines in the wrong order.
For many years AutoCAD has had an edit Polyline function that can convert line and arc segments to polylines, edit line width settings, apply fit or spline curves and provides the ability to insert new vertices to a polyline shape without using commands like trim or explode.
To insert a new vertex into an existing polyline, execute the Edit Polyline command or type ‘Pedit’ in on the command prompt. Select the polyline and choose Edit Vertex. This will display an active vertex cursor whose position can be cycled along the shape by using Next or Previous Vertex options. To create a new vertex choose Insert and position the point using appropriate tracking, snap, or direct distance options. This step can be repeated as often as required. The benefit of editing polylines this way is that the polyline is retained as a singular entity rather that a sequence of separate segments. Also, any field linked to the polyline will still be linked to the element’s properties. This command can also add additional segments to a polyline length. Within the edit vertex mode, set the active vertex to the end point and choose ‘insert’ to add new segments to the line.
Once modified to see the resultant change on a field entity either save the drawing or perform a screen Regen command to refresh the screen.