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Autocad for dummies - Byrnes D.

Byrnes D. Autocad for dummies - Wiley publishing, 2007. - 435 p.
Download (direct link): autocad2006.pdf
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After you create a polyline, you can adjust its segments by grip editing any of the vertex points. (The little squares on the vertices in Figure 6-2 are called grips; see Chapter 7 for details on grip editing.) For more complicated polyline editing tasks, you can use the PEDIT (PE) command to edit the polyline, or you can convert the polyline to a collection of line and arc segments by using the EXPLODE (X) command — although you lose any width defined for each segment when you explode a polyline.
Drawing polylines composed of straight segments is pretty much like drawing with the LINE command, as demonstrated in the following procedure. The PLINE command has lots of options, so watch the prompts! Use the down-arrow key to see the options listed at the crosshairs, or right-click to display the PLINE shortcut menu, or simply read the command line.
Figure 6-2:
Results of drawing with the LINE and PLINE commands.
(each segment is a separate object)
Polyline (all segments form one object)
Chapter 6: Where to Draw the Line 141
To draw a polyline composed of straight segments, follow these steps:
1. Set the desired layer current, and set other object properties that you want applied to the polyline object that you’ll draw.
2. Click the Polyline button — the one that looks like a fishhook — on the Draw toolbar.
AutoCAD starts the PLINE command and prompts you.
Specify start point:
3. Specify the starting point by clicking a point or typing coordinates.
AutoCAD displays the current polyline segment line-width at the command line and prompts you to specify the other endpoint of the first polyline segment.
Current line-width is 0.0000 Specify next point or
4. If the current line width isn’t zero, change it to zero by typing W, Enter, 0, Enter, 0, Enter (as shown in the following command line sequence).
Specify next point or
[Arc/Halfwidth/Length/Undo/Width]: W Enter Specify starting width <0.0000>: 0 Enter Specify ending width <0.0000>: 0 Enter Specify next point or
Despite what you may think, a zero-width polyline segment is not the AutoCAD equivalent of writing with invisible ink. Zero width means “display this segment, using the normal, single-pixel width on the screen.”
5. Specify additional points by clicking or typing.
After you specify the second point, AutoCAD adds the Close option to the prompt. The command line shows:
Specify next point or
In addition, you can view and choose options from the Dynamic Input menu, as shown in Figure 6-3.
6. After you finish drawing segments, either press Enter (to leave the figure open) or type C and press Enter (to close it).
AutoCAD draws the final segment. The blank command line indicates that the PLINE command is finished.
142 Part II: Let There Be Lines
Figure 6-3:
Getting in the PLINE.
-of.\ ctn
In the following procedure, we spice things up a bit and give you a preview of coming (curvy) attractions by adding an arc segment to a polyline.
Just so you know, curved segments in polylines are circular arcs — pieces of circles that you can draw with the AutoCAD ARC (A) command. AutoCAD can draw other kinds of curves, including ellipses and splines, but not within the PLINE command.
To draw a polyline that includes curved segments, follow these steps:
1. Repeat Steps 1 though 5 of the previous procedure.
2. When you’re ready to add one or more arc segments, type A and press Enter to select the Arc option.
The prompt changes to show arc segment options. Most of these options correspond to the many ways of drawing circular arcs in AutoCAD; see the “Arc-y-ology” section, later in this chapter. The command line shows:
Specify endpoint of arc or
[Angle/CEnter/CLose/Direction/Halfwidth/Line/R adius/Second pt/Undo/Width]:
3. Specify the endpoint of the arc by clicking a point or typing coordinates.
AutoCAD draws the curved segment of the polyline. The prompts continue to show arc segment options.
Specify endpoint of arc or
[Angle/CEnter/CLose/Direction/Halfwidth/Line/R adius/Second pt/Undo/Width]:
Chapter 6: Where to Draw the Line 143
Figure 6-4:
A plethora of polylines.
Your options at this point include
• Specifying additional points to draw more arc segments.
• Choosing another arc-drawing method (such as Center or Second pt).
• Returning to drawing straight-line segments with the Line option.
In this example, we return to drawing straight-line segments.
Perhaps the most useful of the alternative arc-drawing methods is Second pt. You can use it to gain flexibility in the direction of the arc, but at the cost of losing tangency of contiguous segments. Sometimes it’s best not to go off on a tangent, anyway.
4. Type L and press Enter to select the Line option.
Specify endpoint of arc or
[Angle/CEnter/CLose/Direction/Halfwidth/Line/R adius/Second pt/Undo/Width]: L
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