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Polylines

May 20, 2011

With ZWCAD, a polyline is a connected sequence of arcs and lines that is treated as a single object. You can draw a polyline with any linetype and using a width that either remains constant or tapers over the length of any segment. When editing a polyline, you can modify the entire polyline or change individual segments.

After you specify the start point of a polyline, the command line prompt several options as you draw, such as Arc, Distance, Halfwidth, and Width. You can specify different starting and ending widths to create a tapered polyline segment.

After you draw at least one polyline segment, you can use the undo tool in right click menu to remove the previous segment. After you draw two or more polyline segments, you can type close in the command line to complete the command by drawing a segment that ends at the start point of the first polyline segment you drew.

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Curved polyline with tapered width. Polyline with straight segments Closed polyline

To draw a polyline with straight segments

  1.   Choose Draw > Polyline.

  2.   Specify the start point.

  3.   Specify the endpoint of each segment.

  4.   Press Enter to end, or enter c to close the polyline.

Draw toolbar\

Command line PLINE

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Polyline start point (A) and segment endpoints (B).


With the Draw Arcs option, you can continually draw arc segments until you select the Draw Lines option to go back to drawing line segments. When you draw arc segments, the first point of the arc is the endpoint of the previous segment. By default, you draw arc segments by specifying the endpoint of each segment. Each successive arc segment is drawn tangent to the previous arc or line segment. If you type close while in the Draw Arcs option, the closing segment is created as an arc.

You can also specify the arc using any of the following methods:

  •      Start point, center point, included angle

  •      Start point, center point, chord length

  •      Start point, center point, endpoint

  •      Start point, endpoint, included angle

  •      Start point, endpoint, Direction

  •       Start point, endpoint, radius

  •      center point, Start point, endpoint

  •      center point, Start point, included angle

  •      center point, Start point, chord length

With more unique functions, editing the polyline is different from that of single lines,such as adjusting width and curvature of polylines, the additional fuctions are shown as follows:

  •      Edit it with PEDIT command

  •      Use EXPLODE to convert it to individual line and arc segments

  •      Use SPLINE to convert a spline-fit polyline into a true spline

  •      Use closed polylines to create a polygon

  •      Create a polyline from the boundaries of overlapping objects

Draw a line and arc combination polyline

Polylines are consist of multiple lines and arcs, when drawing a polyline, use the endpoint of previous line segment as the start point of next arc segment. You can specify angle, center , direction and radius of circle for drawing arcs, and specify a center point and an endpoint as well.

To draw a line segment followed by an arc polyline segment

  1. Choose DRAW > Polyline.

  2. Specify the start point.

  3. Specify the endpoint.

  4. In the command prompt, choose Arc.

  5. Specify the endpoint of the arc segment.

  6. To complete the command, Press ENTER.

Draw toolbar \

Command line PLINE

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You can edit entire polylines and individual segments using the Edit Polyline tool on the Modify II toolbar. You can convert polylines into arc and line entities using the Explode tool on the Modify toolbar.


Create Closed Polylines

When creating polylines with PLINE command, the Close option is only available if no less than two line or arc segments are drawn. A closed polyline object is drawn if you connect the start point of the polyline to endpoint of the last line or arc segment with a line or arc.

Create Wide Polylines

You can draw polylines of various widths by using the Width and Halfwidth options. The Width and Halfwidth options set the width of the next polyline segments you draw.You can set the width of individual segments and make them taper gradually from one width to another.

Zero (0) width produces a thin line. Widths greater than zero produce wide lines, which are filled if Fill mode is on and outlined if Fill mode is off. The Halfwidth option sets width by specifying the distance from the center of the wide polyline to an outside edge.

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If you chose Width option, prompts in command line require you to enter starting width and ending width. While entering different value results in a varying width from the start point to its end. Both the start point and endpoint are located at the center of Wide polyline.


Commands Reference

3DPOLY: Creates a polyline of line segments in 3D space

BOUNDARY: Creates a region or a polyline from an enclosed area

OFFSET: Creates concentric circles, parallel lines, and parallel curves

PEDIT: Edits polylines and three-dimensional polygon meshes

PLINE: Creates two-dimensional polylines

System Variables Reference

FILLMODE: Specifies whether hatches (including solid-fill), two-dimensional solids, wide polylines, are filled in

HPBOUND: Controls the object type created by the BHATCH and BOUNDARY commands

PLINEGEN: Sets how linetype patterns generate around the vertices of a 2D polyline

PLINETYPE: Specifies whether optimized 2D polylines are used

PLINEWID: Stores the default polyline width


 

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