Editing Polylines


Polylines are a great drawing tool because you can use them to perform a number of functions. If you outline an area with a polyline, you can quickly get the area of the outline by checking the properties of the polyline. You can easily convert closed polylines to 3D objects. You can form curves or quickly round the corners of polylines using the Fillet command.

As with other objects, you can edit a polyline using AutoCAD's grip-editing feature. You can click a polyline to expose its grips and then move the individual grips to reshape the polyline. But an object as versatile as the polyline requires a special tool for editing. The Pedit command lets you fine-tune a polyline's shape. You can add line segments to polylines with Pedit, as well as straighten a polyline or add a new vertex. You can even adjust the overall width of a polyline or taper a polyline to form an arrow.

To use the Pedit command, do the following:

  1. Choose Modify è Object è Polyline, or enter Pe at the command prompt.

    image from book
    REDUCING BLOCKS AND POLYLINES TO SIMPLE LINES AND ARCS WITH EXPLODE

    The Explode command can reduce some of the more complex AutoCAD objects to basic objects. You can reduce polylines, for example, to lines or arcs. You can "unblock" blocks into their constituent objects. You can reduce hatch patterns to lines.

    Explode is easy to use. In the 2D Draw control panel, click the Explode tool, choose Modify è Explode, or enter x at the command prompt. At the Select objects: prompt, click the object or objects you want to explode, and press .

    image from book

  2. At the Select polyline or [Multiple]: prompt, select the polyline you want to edit. If you want to edit multiple polylines, enter m, and then select them. You'll see the following prompt:

     Enter an option [Close/Join/Width/Edit vertex/Fit/Spline/Decurve/Ltype gen/Undo]: 

  3. Enter the capitalized letter of the option you want to use, and then follow the prompts to complete the edit.

If you have Dynamic Input turned on, the prompt options appear as a list by the cursor. You can then select the option you want.

Once you've performed the edit, you are returned to the Pedit prompt. To exit Pedit, press at the prompt without selecting an option. Table 5.1 describes the functions of the Pedit options.

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Table 5.1: The Pedit Options
Open table as spreadsheet

OPTION

FUNCTION


Close/Open

If the polyline is closed, the Open option appears and allows you to change the polyline from closed to open. If the polyline is open, Close lets you close it.

Join

Lets you join polylines, arcs, and lines to form a single polyline.

Width

Lets you adjust the width of a polyline. You can also use the Properties palette to do this.

Edit Vertex

Opens another set of options that let you edit the vertices of a polyline. You can remove vertices, insert new vertices, and change the width of the polyline at specific vertices to name a few options. See Table 5.2.

Fit

Changes the polyline to a series of arcs that pass through the vertices. See Chapter 3.

Spline

Changes the polyline into a spline curve. See Chapter 3.

Decurve

Converts a fit or spline polyline into one of straight-line segments.

Ltype Gen

Adjusts the way linetypes are displayed. With Ltype Gen turned on, linetypes ignore vertices when generating line patterns.

Undo

Undoes the last Pedit change of the current Pedit session.

image from book
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Table 5.2: The Edit Options of the Pedit Command
Open table as spreadsheet

OPTION

FUNCTION


Next

Moves the x marker to the next vertex for editing.

Previous

Moves the x marker to the previous vertex for editing.

Break

Lets you break the polyline from the current vertex marked by the x to the next. You'll see the prompt [Next/Previous/Go/eXit] <N>:, which lets you move the x marker to the next or previous vertex. The Go option performs the break after you've moved the x marker.

Insert

Lets you insert a vertex. The inserted vertex is added in the direction of the next vertex.

Move

Lets you move a vertex.

Regen

Regenerates the polyline after you've made a change using one of the edit options.

Straighten

Lets you straighten a polyline between two vertices. You'll see the prompt [Next/Previous/Go/eXit] <N>:, which lets you move the x marker to the next or previous vertex. The Go option straightens the polyline by removing intermediate vertices after you've moved the x marker.

Tangent

Lets you change the tangent direction of a vertex.

Width

Lets you change the width of the polyline at the current vertex.

eXit

Exits the Edit option of the Pedit command. You are returned to the Pedit prompt.

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Pedit also lets you convert a line or arc into a polyline. Start the Pedit command, and then at the Select polyline: prompt, select the line or arc. You are asked whether you want to convert the object into a polyline. Press to accept the default Yes option.

If you select the Edit Vertex option of the Pedit command, you're presented with the following prompt:

 [Next/Previous/Break/Insert/Move/Regen/Straighten/Tangent/Width/eXit] <N>: 

These options let you manipulate the vertices of a polyline. You'll also see an x marker at the beginning of the polyline. The x shows you the vertex that is currently available for editing. It indicates which vertex will be affected by the edit options. Table 5.2 explains what these options do.




Introducing AutoCAD 2008
Introducing AutoCAD 2008
ISBN: 0470121505
EAN: 2147483647
Year: 2007
Pages: 147
Authors: George Omura

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