AutoCAD 2005 for Dummies

C and press Enter (to close it).

AutoCAD draws the final segment and returns to the Command prompt, indicating that the PLine command is finished:

Command:

In the following procedure, I 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 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 through 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 command line prompt changes to show arc segment options. Most of these options correspond to the many ways of drawing circular arcs in AutoCAD; see “Arc-y-ology,” later in this chapter.

Specify endpoint of arc or
 [Angle/CEnter/CLose/Direction/Halfwidth/Line/Radius/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 command line prompt continues to show arc segment options.

Specify endpoint of arc or
 [Angle/CEnter/CLose/Direction/Halfwidth/Line/Radius/Second pt/Undo/Width]:

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, I 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/Radius/Second pt/Undo/Width]: L

The command line prompt changes back to showing straight-line segment options.

Specify next point or
 [Arc/Close/Halfwidth/Length/Undo/Width]:

5. Specify additional points by clicking or typing.

6. After you’re finished drawing segments, either press Enter or type C and press Enter.

Command:

Figure 5-4 shows some of the things that you can draw with the PLine command by using straight segments, arc segments, or a combination of both.

Figure 5-4: A plethora of polylines.

  The Line and PLine commands work well for drawing a series of end-to-end single lines, but what if you want to draw a series of double lines to represent, for example, the edges of a wall or roadway? Here are three options:

? Use the AutoCAD MLine command to draw multilines — series of two or more parallel, straight lines. The AutoCAD multiline feature was full of limitations and bugs when it debuted ten years ago. It hasn’t improved significantly since then. Look up the MLine and MLSTYLE commands in AutoCAD’s online help system if you’d like to tangle with this feature, but be prepared to spend time experimenting and struggling.

? In AutoCAD LT only, use the DLine (Double Line) command to draw pairs of parallel line and/or arc segments. AutoCAD LT doesn’t include the MLine command, which, given MLine’s problems, probably is more of a blessing than a limitation. AutoCAD, on the other hand, doesn’t include the DLine command. (Score one for the little brother!)

? Use the PLine command to draw a single set of connected line and/or arc segments, and then use the Offset command to create one or more sets of parallel segments. Chapter 6 covers the Offset command.

Square off with rectangle

You can use the PLine or Line command to draw a rectangle segment by segment. In most cases, though, you’ll find it easier to use the special-purpose RECtang command. The following procedure demonstrates how: 

1. Set object properties to the layer and other properties that you want applied to the rectangle that you’ll draw.

2. Click the Rectangle button on the Draw toolbar.

AutoCAD starts the RECtang command and prompts you at the command line to specify a point for one corner of the rectangle:

Specify first corner point or
 [Chamfer/Elevation/Fillet/Thickness/Width]:

  You can add fancy effects with the additional command options. The default options work best for most purposes. Look up “RECTANG command” in the AutoCAD help system if you want to know more about the options. 

3. Specify the first corner by clicking a point or typing coordinates.

The command line prompts you to specify the other corner of the rectangle — the one that’s diagonally opposite from the first corner:

Specify other corner point or [Dimensions]:

4. Specify the other corner by clicking a point or typing coordinates.

  If you know the size of the rectangle that you want to draw (for example, 100 units long by 75 units high), type relative coordinates to specify the dimensions (for example, @100,75). (Chapter 4 describes how to type coordinates.)

AutoCAD draws the rectangle.

Choose your sides with polygon

Rectangles and other closed polylines are types of polygons, or closed figures with three or more sides. The AutoCAD POLygon command provides a quick way of drawing regular polygons — polygons in which all sides and angles are equal. (If regular polygons seem a little square, maybe that’s because a square is a special case of a regular polygon!)

The following procedure demonstrates the POLygon command: 

1. Set object properties to the layer and other properties that you want applied to the polygon that you’ll draw. 

2. Click the Polygon button on the Draw toolbar.

AutoCAD starts the POLygon command and prompts you at the command line to enter the number of sides for the polygon:

Enter number of sides <4>:

3. Type the number of sides in the polygon that you want to draw and press Enter.

The command line prompts you to specify the center point of the polygon:

Specify center of polygon or [Edge]: