Like the LINE command, PLINE continues to prompt you for more points, repeating the entire prompt each time. When you're done, press Enter to end the command.

If you choose Arc, you see the Specify endpoint of arc or [Angle/CEnter/CLose/Direction/Halfwidth/Line/Radius/Second pt/ Undo/Width]: prompt. Most of the options are similar to the ARC command options. For details, see Chapter 7. The arc options are as follows:

PLINE continues to display the arc submenu until you use the Line suboption or end the command by pressing Enter.

The drawing used in the following exercise on drawing polylines, ab16-a.dwg, is in the Drawings folder on the DVD.

STEPS: Drawing Polylines

Generating linetypes on polylines

When you create a polyline with a noncontinuous linetype, you may find that the linetype doesn't appear properly along the polyline. One reason is that the segments of the polyline may be too short to fit the entire linetype definition — in this case the polyline appears continuous. You can choose to generate the linetype continuously along the polyline, instead of starting the linetype definition anew at each vertex. This results in a more normal-looking linetype along the polyline. To do this, you need to turn on the PLINEGEN system variable. To turn on PLINEGEN, type plinegen

As explained in the section "Editing polylines with the PEDIT command" later in the chapter, you can also modify the display of linetypes for existing polylines.

When you choose the Edit Vertex option, you see a new set of suboptions with the Enter a vertex editing option [Next/Previous/Break/Insert/Move/Regen/Straighten/Tangent/Width/eXit] <N>: prompt. You see an X at one of the vertices. This is the current vertex, which you can edit. The suboptions are as follows:

You can also edit polylines with grips. A polyline has a grip at each vertex, making it easy to move vertices.

To edit multiple polylines at one time, follow these steps:

You can also join two polylines that aren't touching, if you use the Multiple option first. Select the polylines and then choose the Join option. You then need to specify two suboptions:

You can edit selected polylines in the Properties palette. You can choose a vertex by clicking Vertex in the Geometry section of the palette, and use the left and right arrows to move to another vertex. An X appears on the polyline to let you know which vertex you've chosen. You can then edit the vertex's coordinates by typing them in, or by clicking the Pick a Point button that appears and then picking a point in the drawing. You can change the start and ending widths and specify a global width for the entire polyline.

You can close and open a polyline in the Misc section. You can also turn on continuous linetype generation for the selected polyline by choosing Linetype generation and then choosing Enabled from the drop-down list that appears. Of course, you can also change the layer, color, linetype, lineweight, and linetype scale.

STEPS: Editing Polylines

If you choose a point, the command displays the Specify next point: prompt so that you can pick a second point. After you do so, you see the Specify next point or [Close/Fit tolerance] <start tangent>: prompt. Use these options as follows:

STEPS: Drawing Splines

Like polylines, splines have their own editing command. To understand how to edit splines, you need to understand how your drawing stores them.

When you pick points to create the spline, AutoCAD stores these points as fit points (or data points). If the tolerance is zero, the curve lies on these fit points. When you select a spline at the command line, grips appear at these fit points. However, when you use the SPLINEDIT command, to see the fit points as grips, you must choose the Fit Data option first. Only then can you edit the fit points.

AutoCAD and AutoCAD LT calculate control points based on the fit points. The spline is then calculated based on the control points, not the fit points. Most of the control points are not on the spline. When you use SPLINEDIT to edit a spline, and use the Move vertex option described later, you see the control points displayed as grips, and you can move the control points.

The left side of Figure 16.7 shows a spline created by using point objects as the fit points; these are the points that were picked when creating the spline. Note that the spline passes through each fit point. On the right, you see the same spline selected with no command active. Notice that the grips are exactly on the fit points.

Figure 16.7. On the top, you see the point objects that were used as the pick points. These are the fit points of the spline. On the bottom, you see the spline with no command active, and the grips are on the fit points.

Because the spline is calculated based on the control points, the fit points are not necessary to generate the spline. In fact, if you use the Move vertex or Refine options to move or edit a control point, only the control points are needed to generate the spline, and the fit point information is discarded so that you can no longer edit it. The Fit Data option also disappears from the prompt. You can edit the fit points by using grips.

To edit a spline, choose Home tab

When you use the SPLINEDIT command and select a spline, you see control points, not fit points. In Figure 16.8, the grips indicate the control points.

Figure 16.8. When you choose the SPLINEDIT command and select a spline, the grips indicate the control points, which are not generally on the spline.

If you choose the Fit Data option, you see the Enter a fit data option [Add/Close/Delete/Move/Purge/Tangents/toLerance/eXit] <eXit>: prompt. Descriptions of these options follow:

When you use SPLINEDIT and choose the Fit Data option, the grips appear on the fit points so that you can edit them. You can edit a spline in the Properties palette or the Quick Properties palette. It works similarly to editing a polyline. The Properties palette displays the fit points or the control points so that you can change them.

Hatch patterns may seem complex, but they are easy to use, after you understand how they work. Hatch patterns have three characteristics that are similar to dimensions:

You have several ways to specify exactly which area you want to hatch. Often, the key to successful hatching lies in how you construct the area that you want to hatch. For example, you can use the BOUNDARY and REGION commands covered in previous sections of this chapter to create complex closed areas that you can hatch.

AutoCAD stores hatch pattern definitions in the acad.pat and acadiso.pat files. AutoCAD LT uses the acadlt.pat and acadltiso.pat files. If you create your own hatch patterns, you can put them in another file with the PAT filename extension.

Hatching an entire object is the simplest way to place a hatch. However, the area that you want to hatch is often fairly complex, and the program needs to do some calculations to determine the area.

The Hatch and Gradient dialog box offers two ways to specify the hatch boundary: You can pick points inside an area and let the command try to find an enclosed boundary, or you can select objects. If you want to hatch an entire object, choose Add: Select Objects. You return temporarily to your drawing. Then select the object or objects, and press Enter to end object selection and return to the dialog box.

If the area you want to hatch does not neatly fit into one or more objects, choose Add: Pick Points. You return to your drawing and see the following:

Pick internal point or [Select objects/remove Boundaries]: Selecting everything...
Selecting everything visible...
Analyzing the selected data...
Analyzing internal islands...
Pick internal point or [Select objects/remove Boundaries]:

The command is determining the boundary set, which is simply everything visible on the screen. At the Pick internal point or [Select objects/remove Boundaries]: prompt, pick a point that is inside the boundary that you want to hatch. You can continue to pick internal points to hatch adjoining areas. Each boundary is helpfully highlighted. Press Enter to return to the dialog box.

Sometimes, you need more control over the boundary and also need to remove a boundary that you've selected, without starting from scratch. To remove a boundary, click the Remove Boundaries button in the dialog box. In your drawing, when you see the Select objects or [Add boundaries]: prompt, select the objects that you want to remove. For example, if you have an inner island that you want to hatch, then by default, the hatch excludes the island. One way to hatch the island is to remove its boundary.

If you choose the Add Boundaries option, you can either select additional objects or pick internal points. Press Enter when you're done, to return to the dialog box.

While you're in your drawing, either before or after picking points or selecting objects, you can right-click to open a very useful shortcut menu. This shortcut menu enables you to manage the hatch boundary without returning to the dialog box. Choose from the following options on the shortcut menu:

Previewing the hatch before applying it is always a good idea. After previewing a hatch, right-click to accept the preview and place the hatch. Press Esc or left-click to return to the Hatch and Gradient dialog box. From the dialog box, click OK to create the hatch and return to your drawing.

Note

To display hatches, either solid fill or lines, the FILLMODE system variable must be on, which it is by default. To turn FILLMODE off, type fillmode

The dialog box has several other options:

Islands

Islands are enclosed areas entirely inside a hatch boundary. Islands make hatching more difficult because you may or may not want to hatch the inside of the island.

Note

Text is counted as an island, enabling you to hatch areas that contain text without hatching over the words.

Managing islands when you select objects to hatch

When you choose the hatching boundary by selecting objects, you must also select the islands. If you select the entire area by window, you automatically include the internal islands. If you need to pick individual objects, you must also pick the islands individually. If you later erase an island, you don't lose hatch associativity, and the hatch regenerates so that it covers the entire outer boundary.

The resulting hatch depends on the boundary style. To specify the boundary style, in the Hatch and Gradient dialog box, click the right arrow at the lower-right corner of the dialog box to display the expanded section, shown on the right in Figure 16.14, earlier in this chapter.

Three boundary styles affect how islands are hatched:

• Normal. Hatches alternating areas so that the outer area is hatched, the next inner island is not hatched, the next inner island is hatched, and so on.

• Outer. Hatches only the outer area and does not hatch any inner islands.

• Ignore. Ignores islands and hatches everything from the outside in.

Figure 16.19 shows three copies of a nut hatched in the three styles. To hatch this model, I selected the entire model, except for the spout at the bottom, with a window.

Figure 16.19. Hatching islands using the three boundary styles.

Managing islands when you pick points to specify the hatch

When you pick points instead of selecting objects, you don't need to select the islands. Hatching detects islands by default. As soon as you pick points, the Remove Boundaries button becomes available, and you can select the islands to remove them from consideration if you want to hatch them. For example, if you remove all the islands shown in Figure 16.19, the result is the same as using the Ignore style, where everything inside the outside boundary is hatched.

After you have spent the time creating a hatch, you may want to use that hatch in other drawings. You can open a PAT (hatch pattern) file from the DesignCenter, preview its hatch patterns, and drag any hatch pattern into any closed object in your current drawing. Here's how to drag a hatch pattern from the DesignCenter:

You can drag a hatch pattern to a tool palette to create a hatch with the properties of the hatch in your drawing. Then you can drag that hatch tool onto any closed area in your drawing. The hatch automatically fills the area with the same properties. For more on tool palettes, see Chapter 26.

Gradients are fills that gradually change from dark to light or from one color to another. You can use gradients to create presentation-quality illustrations without rendering. You can also use gradients as a substitute for shading because they offer more flexible options.

To create a gradient:

You can use the Gap Tolerance feature to fill an almost-enclosed area with a gradient. For more information, see the discussion on hatches in the "Other advanced options" section earlier in this chapter.

See Figure 16.21 for an example of some gradient fills. You could turn off the boundary's layer for a more realistic look.

Figure 16.21. The gradient on the left gives the illusion of light shining from the left. On the right, you see a sophisticated use of gradients to create a presentation-quality drawing.

To edit a hatch pattern, including a solid or gradient, choose Home tab

The Hatch Edit dialog box is exactly the same as the Hatch and Gradient dialog box, except that not all the options are available. You can use this dialog box to change any of the hatch properties. You can change the boundary style on the expanded area of the dialog box. You can also preview the hatch. After you make your changes, click OK to return to your drawing.

Because hatches are associative (unless you explode them or choose to create them as nonassociative), when you edit their boundaries, they adjust to fit the new boundary. However, if the new boundary is no longer closed, the hatch may lose its associativity, and you see the Hatch boundary associativity removed warning message.

By default, object snaps don't work with hatch lines. This prevents you from accidentally drawing to a hatch line instead of a nearby object. If you want to snap to hatch lines, choose Application Button

You can also edit a gradient (AutoCAD only) in the Properties palette; use the items in the Pattern section. You can change the colors, angle, type, and whether it is centered.

You may find it difficult to select solid fill hatches. In some locations, you can pick the solid hatch, while at other points, you get the Other corner: prompt, meaning that no object was found. If necessary, try a crossing window at the edge of the hatch. This always selects the solid hatch but also selects the boundary. Hatches have a grip at their center. If you can find the grip and include it in the window, you can easily select the solid hatch. When the hatch highlights as you hover the mouse over it, you can pick to select it.

STEPS: Creating and Editing Hatches

The SOLID command creates solidly filled 2D areas. (It is not directly related to 3D solids.) In general, BHATCH is much more flexible. Although the SOLID command is a 2D command, it's sometimes used in 3D drawing. When you create a 2D solid and give it thickness, it creates surfaces with tops and bottoms. I cover using thickness in Chapter 21.

SOLID creates straight-edged shapes. If FILLMODE is on, AutoCAD or AutoCAD LT fills in the shape with a solid fill. (That's why it's called SOLID.)

To draw a solid, type solid

The first step in drawing multilines is to design the multiline style. To create a multiline style, type mlstyle

Figure 16.24. The Multiline Style dialog box.

Like text styles and dimension styles, multiline styles group a set of properties under one name. The default multiline style, called Standard, defines two lines, one unit apart. Multiline styles have two parts: element properties and multiline properties. The element properties define each individual line element. The multiline properties define properties that apply to the multiline as a whole.

Defining multiline style properties

To start defining the multiline style, click New. In the Create New Multiline Style dialog box, type a name and click Continue. The New Multiline Style dialog box opens, as shown in Figure 16.25.

Figure 16.25. The New Multiline Style dialog box.

The Elements section lists the current elements of the multiline. Elements are the lines that make up the multiline. The offset defines the distance of the line from the start point when you start to draw. An offset of zero places the line on the start point. As you can see, the Standard multiline style has two elements, each 0.5 units from the start point. Figure 16.26 shows the Standard multiline style as it appears in relation to the start point that you pick.

Figure 16.26. The Standard multiline style places two lines on either side of the start point.

Note

You can change the relationship of the start point and the element lines with the Justification option, as explained later in the "Drawing multilines" section.

To define the element lines of a multiline style, follow these steps:

1. In the Elements section, highlight the first element. Even if you typed a new name for the multiline style, the elements listed are the same as the current multiline style.

   Tip

   When creating a new multiline style, first set as current the multiline style that is the most similar to the one that you want to create.

2. In the Offset box, type the offset value that you want. The offset should be zero if you want the line to appear on your pick points, a positive number (in units) if you want the line to appear above your pick points, and a negative number (in units) if you want the line to appear below your pick points. (This assumes the default of zero justification, explained later in this chapter.)

   Tip

   When defining the multiline style elements, think of the multiline as being drawn horizontally to the right to help you visualize what above and below mean.

3. Choose Color to choose a color for the line element.

4. Choose Linetype to choose a linetype for the line element.

5. Choose Add to add a new element, or choose Delete to delete a listed element.

6. To define the next element, select the second element in the Elements box and repeat Steps 2 through 5. Continue to define elements until you're done.

7. If you want, enter a description for the multiline style in the Description text box.

8. Click OK to return to the Multiline Style dialog box.

Note

A multiline style can have up to 16 elements. All 16 elements must be on the same layer, but you can vary the linetypes and colors.

Use the left side of the New Multiline Style dialog box to set the overall properties of the multiline. Caps cross the ends of multilines to close them. You can choose line or arc caps. Figure 16.27 shows the effects of all the possible choices in this box. You can also choose a color to add a solid fill to the multiline. To display a line at the junction of each line segment, check the Display Joints check box. After you make your choices, click OK to return to the Multiline Style dialog box.

Loading a multiline style

As with linetypes, you must load multiline styles before you can use them. Choose Load to open the Load Multiline Styles dialog box. Choose the style that you created from the list and click OK. You return to the Multiline Styles dialog box. You're now ready to use the multiline style. Click OK to return to your drawing.

You can also use the Multiline Style dialog box to rename multiline styles and make another multiline style current.

Figure 16.27. The results of choosing the various options in the New Multiline Style dialog box.

Note

The drawing used in the following exercise on creating a multiline style, ab16-g.dwg, is in the Drawings folder on the DVD.

STEPS: Creating a Multiline Style

1. Open ab16-g.dwg from your DVD.

2. Save the file as ab16-07.dwg in your AutoCAD Bible folder. This is a site plan, as shown in Figure 16.28.

   

   Figure 16.28. The parallel lines at the bottom of the site plan can be drawn by using a multiline.

3. Type mlstyle

   

4. In the Elements section of the dialog box, the top element should be highlighted. Change the offset to 0, the color to black (it may list as white), and the linetype to DASHDOT.

5. Highlight the second element. Change the offset to −132 (11' × 12″), the color to magenta, and the linetype to continuous.

6. Click Add. Change the offset to −180 (15' × 12″), the color to red, and the linetype to center.

7. Click Add. Change the offset to −228 (19' × 12″), the color to magenta, and the linetype to continuous.

8. Click Add. Change the offset to −360 (30' × 12″), the color to black, and the linetype to dashdot.

9. Click Add. Change the offset to −480 (40' × 12″), the color to red, and the linetype to center.

10. Click OK. In the Multiline Style dialog box, click Save.

    Warning

    If you are using someone else's computer, check with the owner before saving the linestyle to acad.mln. You can't do any damage, but the owner may not want to have your multiline style there. You can change the name in the File Name text box to something else, such as my_mls.mln.

11. In the Save Multiline Style dialog box, you should see acad.mln in the File Name text box. You can also type a new MLN filename. Choose Save.

12. With the new multiline style selected, choose Set Current, and click OK to return to your drawing.

13. Save your drawing. If you're continuing on to the next exercise, keep the drawing open.

Defining a multiline style is the hard part. As soon as the style is defined, saved, loaded, and made current, you can draw with it. You may find that you need some practice to get the hang of it because you're drawing more than one line at once. To draw a multiline, type mline

As you draw a multiline, whenever you create a corner by changing direction, the command creates a clean corner.

STEPS: Drawing Multilines

Figure 16.30. The completed multiline.

No matter how many segments it contains, the entire multiline is one object. Many editing commands simply do not work with multilines. Table 16.1 shows the editing commands and whether they work with multilines.

You can use grips to stretch, move, copy, mirror, and rotate multilines.

To edit multilines, you use the MLEDIT command. To start MLEDIT, type mledit

This dialog box enables you to edit multiline intersections and corners. You can also add or delete a vertex. Click one of the images, and its name appears at the bottom of the dialog box.

Figure 16.31. The Multilines Edit Tools dialog box.

The first column manages crossing intersections. To edit a crossing intersection, choose one of the tiles in the first column and click OK. The command prompts you to pick a first multiline and then a second multiline. MLEDIT always cuts the first multiline that you pick. The second one may be cut if it is called for by the edit type.

The second column manages T-shaped intersections. To edit a crossing intersection, choose one of the tiles in the second column and click OK. The command prompts you to pick a first multiline and then a second multiline. MLEDIT always cuts the first multiline that you pick. The second one may be cut if called for by the edit type and depending on the shape of the multiline.

The third column manages corners and vertices. The top tile creates a corner. The second tile adds a vertex, and the third deletes a vertex. Choose the edit that you want and click OK. The command prompts you to select a multiline. Be careful — you must pick the point where you want to add or delete the vertex. To see the current vertices, pick the multiline with no command active to see the grips.

The last column of the dialog box makes cuts through multilines and welds them back together again. Here's how to use these options:

For all these editing tools, you get prompts for further edits. Press Enter to end selection.

You can also move vertices by using grips with the Stretch option.

Multiline styles are stored with the drawing, so you can update and view them even if the multiline style file containing the multiline definition is not available.