Polyline Types
In AutoCAD Release 13 and earlier, polylines were generated and stored in AutoCAD’s database differently. The replacement polyline produces a “leaner,” optimized object, sometimes referred to as a “Lightweight Polyline.” Some of the functionality and control available in the older 2D polyline objects (such as arc fit curve data, spline fit data, and curve fit tangent direction data) are not available in the current 2D optimized polyline.
To provide compatibility with the 2D polyline objects in AutoCAD before Release 14, the system variable PLINETYPE is provided. PLINETYPE specifies whether or not AutoCAD creates the newer optimized 2D polylines. It controls both the creation of new polylines with the PLINE command and the conversion of existing polylines in drawings from previous releases. PLINETYPE can have one of three settings:
| 0 | Polylines in older drawings are not converted when opened; PLINE creates old-format polylines. |
| 1 | Polylines in older drawings are not converted when opened; PLINE creates optimized polylines. |
| 2 | Polylines in older drawings are converted when opened; PLINE creates optimized polylines. This is the default setting. |
An optimized polyline can have the following characteristics:
Straight line segments
Arc segments
Constant and variable width
Thickness
Note
PLINETYPE also controls the polyline type created by using the following commands: BOUNDARY (when object type is set to Polyline); DONUT; ELLIPSE (when PELLIPSE is set to 1); PEDIT (when selecting a line or arc); POLYGON; and SKETCH (when SKPOLY is set to 1).
You also can manually convert the older 2D polylines by using the CONVERT command, which is described next.
The CONVERT Command
The CONVERT command allows you to “manually” optimize 2D polylines created in AutoCAD Release 13 and earlier. The prompts for the CONVERT command are as follows:
Enter type of objects to convert [Hatch/Polyline/All] <All>:
You enter H for hatches, P for polylines, or A for both. The next prompt then appears:
Enter object selection preference [Select/All] <All>:
Enter S to select objects or A to convert all candidate objects in the drawing. Depending on your response to these two prompts, AutoCAD displays one or both of the following messages:
number hatch objects converted. number 2d polyline objects converted. (Where number is the number of objects converted.)
In most cases, you do not need to convert polylines with the CONVERT command because the PLINETYPE system variable (described in the previous section) specifies that polylines are updated automatically whenever you open an older drawing. However, older, non-optimized polylines might be created in your AutoCAD 2000 drawing by third-party applications or they may be part of an older drawing that is inserted as a block into your current drawing and then exploded.
Note
Polylines that contain curve fit or splined segments always retain the old-style format, as do polylines that contain extended entity data.