2D and 3D polylines, rectangles, polygons, and 3D polygon meshes are all polyline variants and are edited in the same way.
AutoCAD recognizes both fit polylines and spline-fit polylines. A spline-fit polyline uses a curve fit, similar to a B-spline. There are two kinds of spline-fit polylines: quadratic and cubic. Both polylines are controlled by the SPLINETYPE system variable. A fit polyline uses standard curves for curve fit and utilizes any tangent directions set on any given vertex.
To edit a polyline, use the properties and methods of the LightweightPolyline or Polyline object. Use the following properties and methods to open or close a polyline, change the coordinates of a polyline vertex, or add a vertex:
Opens or closes the polyline.
Specifies the coordinates for each vertex in the polyline.
Adds a vertex to a lightweight polyline.
Use the following methods to update the bulge or width of a polyline:
Sets the bulge of a polyline, given the segment index.
Sets the start and end width of a polyline, given the segment index.
For more information about editing polylines, see ‚ÄúModify or Join Polyline‚ÄĚ in the User's Guide.
This example creates a lightweight polyline. It then adds a bulge to the third segment of the polyline, appends a vertex to the polyline, changes the width of the last segment, and finally closes the polyline.
Dim plineObj As AcadLWPolyline
Dim points(0 To 9) As Double
' Define the 2D polyline points
points(0) = 1: points(1) = 1
points(2) = 1: points(3) = 2
points(4) = 2: points(5) = 2
points(6) = 3: points(7) = 2
points(8) = 4: points(9) = 4
' Create a light weight Polyline object
Set plineObj = ThisDrawing.ModelSpace. _
' Add a bulge to segment 3
plineObj.SetBulge 3, -0.5
' Define the new vertex
Dim newVertex(0 To 1) As Double
newVertex(0) = 4: newVertex(1) = 1
' Add the vertex to the polyline
plineObj.AddVertex 5, newVertex
' Set the width of the new segment
plineObj.SetWidth 4, 0.1, 0.5
' Close the polyline
plineObj.Closed = True