Creating Objects, AutoCAD 2000 User's...

In This Chapter

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6

Creating Objects

With the AutoCAD® drawing tools, you can create a

range of objects, from simple lines and circles to spline

curves, ellipses, and hatched areas that change when

their boundaries change. In general, you draw objects

by specifying points with the pointing device or by

entering coordinate values on the command line.

For information about drawing three-dimensional

objects, see chapter 17, “Working in Three-Dimensional

Space.”

■ Drawing line objects, polylines, multilines, polygons, and freehand sketches

■ Drawing curved objects such as circles, arcs, ellipses, and spline curves

■ Changing the order of objects in a drawing

■ Creating solid-filled areas, regions, and hatched areas

■ Understanding named, custom, and proxy objects

■ Using wild-card characters

124 | Chapter 6 Creating Objects

Drawing Lines

The line is the basic object in AutoCAD. You can create a variety of lines: single lines, multiple line segments with and without arcs, multiple parallel lines, and freehand sketch lines. In general, you draw lines by specifying coordinate points, properties such as linetype or color, and measurements such as angles. See “Specifying Coordinates” on page 110. The default line-type is CONTINUOUS, an unbroken line, but various linetypes are available that use dots and dashes. See “Working with Linetypes” on page 333.

Drawing Line Objects

A line can be one segment or a series of connected segments, but each seg-ment is a separate line object. Use lines if you want to edit individual segments. If you need to draw a series of line segments as a single object, use a polyline (see “Drawing Polylines” on page 124). You can close a sequence of lines so that the first and last segments join to form a closed loop.

To draw a line

1 From the Draw menu, choose Line.

2 Specify the start point (1).

3 Specify the endpoint (2).

4 Specify the endpoints of the next segments (3, 4, 5, 6).

5 Press ENTER to complete the line.

To undo the previous line segment during the LINE command, enter u. You can start a new line at the endpoint of the last line drawn by starting LINE again and pressing ENTER at the Start Point prompt.

Command line LINE

Related PLINE draws polyline line and arc segments that form a single ob-ject. MLINE draws multiple parallel lines. OFFSET creates copies of lines offset at a specified distance to one side or through a point. LINETYPE sets the cur-rent linetype.

Drawing Polylines

A polyline is a connected sequence of line or arc segments created as a single object. Use polylines if you want to edit all segments at once, although you can also edit them singly. You can set the width of individual segments, make segments taper, and close the polyline. When you draw arc segments, the

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Drawing Lines | 125

first point of the arc is the endpoint of the previous segment. You can specify the angle, center point, direction, or radius of the arc. You can also complete the arc by specifying a second point and an endpoint.

Polylines with arc segments

To draw a polyline with straight segments

1 From the Draw menu, choose Polyline.

2 Specify the first point of the polyline.

3 Specify the endpoint of each polyline segment.

4 Enter c (Close) to close the polyline, or press ENTER to end the command.

Command line PLINE

Related LINE creates single or multiple line segments that are separate ob-jects. MLINE creates multiple parallel lines.

In the next example, you draw a polyline line segment, continue with an arc segment, and then draw another line segment in a tangential direction.

To draw a line and arc combination polyline

First draw the line segment.

1 From the Draw menu, choose Polyline.

2 Specify the start point of the line segment (1).

3 Specify the endpoint of the line segment (2).4 Enter a to switch to Arc mode.

5 Specify the endpoint of the arc (3).

6 Enter l to return to Line mode.

7 Enter the distance and angle of the line in relation to the endpoint of the arc. You can enter these relative values in the form @distance<angle.

8 Press ENTER to end the polyline.

an insulated walldiffering widthspipe symbol

endpoint of arc

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final segment


After you’ve created a polyline, you can edit it with PEDIT or use EXPLODE to convert it to individual line and arc segments. When you explode a wide polyline, the line width reverts to 0 and the resulting line segments are posi-tioned along the center of what was the wide polyline.

Drawing Multilines

Multilines consist of between 1 and 16 parallel lines, called elements. You position the elements by specifying the desired offset of each element from the origin of the multiline. You can create and save multiline styles or use the default style, which has two elements. You can set the color and linetype of each element and display or hide the joints of the multiline. Joints are lines that appear at each vertex. There are several types of end caps you can give the multiline, for example, lines or arcs.

Examples of multilines

To draw a multiline

1 From the Draw menu, choose Multiline.

2 At the Command prompt, enter st to select a style.

3 To list available styles, enter the style name or enter ?.

4 To justify the multiline, enter j and choose top, zero, or bottom justification.

5 To change the scale of the multiline, enter s and enter a new scale.

Now draw the multiline.

6 Specify the starting point.

7 Specify the second point.

8 Specify the third point.

9 Specify the fourth point or enter c to close the multiline, or press ENTER.

Command line MLINE

Creating Multiline StylesYou can create named styles for multilines to control the number of elements and the properties of each element. The style also controls the background fill and the end cap. See “Editing Multilines” on page 296.

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five elements

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Drawing Lines | 127

To create a multiline style

1 From the Format menu, choose Multiline Style.

2 In the Multiline Styles dialog box, enter a name and description for the style.

Descriptions are optional and can be up to 255 characters, including spaces.

3 To create a multiline style, choose Add.

4 To add elements to the style or to modify existing elements, choose Element Properties.

5 In the Element Properties dialog box, highlight the element in the list, and then make changes to Offset, Color, and Linetype.

6 To add an element, choose Add, and then make changes to Offset, Color, and Linetype. Choose OK.

The offset defines the 0,0 origin of the multiline relative to which other ele-ments are drawn. An element does not have to be drawn at the origin.

7 To set multiline properties, choose Multiline Properties in the Multiline Styles dialog box.

8 In the Multiline Properties dialog box, make any changes and choose OK.

Properties include the display of segment joints and the type of start and end caps with their angles and fill color.

9 Choose Save to save the style to an external multiline style file (the default is acad.mln). You can save multiline styles to the same file.

If you create more than one multiline style, save the current style before creating a new one or you lose the changes to the first style.

loads stylefrom external file

saves style to external file


You can add up to 16 elements to a multiline style. If you create or modify an element so that it has a negative offset, it appears below the origin in the image tile of the Multiline Styles dialog box.

To specify the properties of the entire multiline

1 From the Format menu, choose Multiline Style.

2 In the Multiline Styles dialog box, choose Multiline Properties.

3 In the Multiline Properties dialog box, select Display Joints to display a line at the vertices of the multiline.

4 Under Caps, select a line or an arc for each end of the multiline, and enter an angle.

Lines cross the end of the whole multiline, and outer arcs join the ends of the outermost elements. Inner arcs connect pairs of elements, leaving the center-line unconnected if there is an odd number of elements. For example, if there are six elements, inner arcs connect elements 2 and 5 and elements 3 and 4. If there are seven elements, inner arcs connect elements 2 and 6 and elements 3 and 5; element 4 is left unconnected.

controls display of end caps

toggles display of multiline joints

controls background fill

line cap outer arc inner arcs with six elements

inner arcs with seven elements

Drawing Lines | 129

5 Under Fill, select On to display a background color.

This color is not displayed in the image tile of the Multiline Styles dialog box.

6 Choose Color.

7 In the Select Color dialog box, select the background fill color and choose OK.

8 In the Multiline Properties dialog box, choose OK to return to the Multiline Styles dialog box.

Next, save the multiline style.

To save a multiline style name

1 In the Multiline Styles dialog box under Name, enter a name and a descrip-tion for the style.

Descriptions are optional and may have up to 255 characters, including spaces.

2 To add the newly created multiline style to the drawing and set it as current, choose Add.

3 To save the style to an external MLN file, choose Save.

4 Choose OK.

Command line MLSTYLE

System variables CMLSTYLE stores the name of the current multiline style.

Related The OFFSET command creates new objects at a specified offset from a selected object or through a specified point.

Using Existing Multiline StylesWhen you start drawing a multiline, you can use the default style, which has two elements, or specify a style you created previously. The default style is the multiline style last used, or the STANDARD style if MLINE hasn’t been used. You can also change the justification and scale of the multiline before you draw it. Justification determines whether the multiline is drawn below or above the cursor, or with its origin centered on the cursor. The default is be-low (top justification). Scale controls the overall width of the multiline using the current units.

Multiline scale does not affect linetype scale. If you are changing the multi-line scale, you might need to make equivalent changes to linetype scale to prevent dots or dashes from being disproportionately sized.


Drawing Polygons

Polygons are closed polylines with between 3 and 1,024 equal-length sides. You draw a polygon by inscribing it in, or circumscribing it about, an imagi-nary circle or by specifying the endpoints of one of the edges of the polygon. Because polygons always have equal-length sides, they provide a simple way to draw squares and equilateral triangles.

The following illustrations show polygons drawn using the three methods. In the first two illustrations, point 1 is the center of the polygon and point 2 defines the radius length, which is being specified with the pointing device.

Three methods for drawing polygons

Drawing Inscribed PolygonsUse inscribed polygons when you want to specify the distance between the center of the polygon and each vertex. This distance is the radius of the circle within which the polygon is inscribed. In this example, you draw an in-scribed square, the default polygon.

To draw an inscribed square

1 From the Draw menu, choose Polygon.

2 Enter 4 to specify four sides for the polygon.

3 Specify the center point for the polygon (1).

4 Enter i (Inscribed in Circle).

5 Specify the radius (2).

Command line POLYGON

Related RECTANG creates polyline rectangles.

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Drawing Lines | 131

Drawing Circumscribed PolygonsUse circumscribed polygons when you want to specify the distance between the center of the polygon and the midpoint of each side. This distance is the radius of the circle the polygon circumscribes.

To draw a circumscribed hexagon

1 From the Draw menu, choose Polygon.

2 Enter 6 for the number of sides.

3 Specify the center of the polygon (1).

4 Enter c (Circumscribed about Circle).

5 Specify the radius length (2).

After you’ve created a polygon, you can edit it with PEDIT or convert it to individual line segments with EXPLODE.

Sketching Freehand

You can use the SKETCH command to draw freehand sketches. Freehand sketches comprise many line segments. Each line segment can be a separate object or a polyline. You set the minimum length or increment of the seg-ments. Sketching is useful for creating irregular boundaries or for tracing with a digitizer. Small line segments allow for greater accuracy, but they can greatly increase the drawing file size. For this reason, use this tool sparingly.

Before sketching, check the CELTYPE system variable to make sure the current linetype is BYLAYER. If you use a linetype with dots or dashes and set the sketch line segment shorter than the spaces or dashes, you won’t see the spaces or dashes.

To sketch, use the pointing device like a pen, clicking to put the “pen” down on the screen to draw and clicking again to lift it up and stop drawing.

Freehand sketches

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To sketch and record freehand lines

1 At the Command prompt, enter sketch.

2 At the Record Increment prompt, enter the minimum line segment length.

3 Click the start point to put the “pen” down.

When you move the pointing device, AutoCAD draws temporary freehand line segments of the length you specified. SKETCH doesn’t accept coordinate input. During the command, freehand lines are displayed in a different color.

4 Click the endpoint to lift the “pen” up so that you can move the cursor around the screen without drawing. Click a new start point to resume draw-ing from the new cursor position.

5 Enter r at any time to record (save) in the database the line you’re drawing and those already drawn.

If the pen is down, you can continue drawing after recording. If the pen is up, click to resume drawing. The freehand line starts from wherever the cursor is when you click.

6 Press ENTER to complete the sketch and record all unrecorded lines.

If you want to use Snap or Ortho mode while sketching, you must use the keyboard toggles (F8 for Ortho, F9 for Snap). The status bar toggles have no effect. The Snap setting overrides the record increment if Snap is the larger setting. If Snap is smaller, the record increment takes precedence.

System variables SKETCHINC sets the size of freehand line segments. SKPOLY draws the freehand line as a polyline if it is not set to 0.

Erasing Freehand LinesYou erase freehand lines by using the Erase option of the SKETCH command. In Erase mode, wherever the cursor intersects the freehand line, everything from the intersection to the end of the line is erased.

Once you record freehand lines, you can’t edit them or erase them with the Erase option of SKETCH. Use the ERASE command after you finish sketching.

To erase freehand lines

1 With the pen up or down, enter e (Erase).

If the pen was down, it moves up.

2 Move the cursor to the end of the line you drew last and then move it back as far along the line as you want to erase.

3 To end the erasure and return to the SKETCH Command prompt, enter p. To undo the erasure, enter e.

If you want to change the current viewport while sketching, make sure the pen is up, all lines entered so far have been recorded, and Tablet mode is off.

Drawing Curved Objects | 133

Sketching in Tablet ModeYou use Tablet mode with a digitizer. Sketching in Tablet mode is useful for such things as tracing map outlines from paper directly into an AutoCAD drawing. You can’t turn off Tablet mode while sketching.

When Tablet mode is on, you can configure AutoCAD to map the paper drawing’s coordinate system directly into the AutoCAD world coordinate system. Thus, there is a direct correlation between the coordinates where screen crosshairs appear, the coordinates on the tablet, and the coordinates in the original paper drawing. After configuring AutoCAD to match the coordinates of the paper drawing, you may find that the area shown on the screen is not the area you need. To avoid this problem, use ZOOM to display the entire work area before you start to sketch.

With some digitizers you can’t select the menus while Tablet mode is on. See your digitizer documentation for details.

Maintaining Sketching AccuracyTo ensure accuracy on a slow computer, set the record increment value to a negative value. SKETCH uses this value as if it were positive but tests every point received from the pointer against twice the record increment. If the point is more than two record increments away, your computer beeps as a warning that you should slow down to avoid losing accuracy. For example, if the record increment is –1, you should move the cursor in increments of no more than 2. Using this method does not slow down the tracing speed.

Drawing Curved Objects

You can create a variety of curved objects with AutoCAD, including circles, arcs, ellipses, spline curves, and donuts.

Drawing Circles

You can create circles in several ways. The default method is to specify the center and radius. You can also specify the center and diameter or define the diameter alone with two points. You can define the circle’s circumference with three points. You can also create the circle tangent to three existing ob-jects or create it tangent to two objects and specify a radius. In the following illustrations, the darker circles are the ones being drawn.


Four methods of drawing circles

To draw a circle by specifying a center point and radius

1 From the Draw menu, choose Circle ➤ Center, Radius.

2 Specify the center point.

3 Specify the radius.

Command line CIRCLE

To create a circle that is tangent to two objects, specify a tangent point on each of the objects and the radius of the circle. The tangent point can be any point on the object. In the following illustrations, the darker circle is the one being drawn, and the tangent points are points (1) and (2).

Circles created tangent to two objects

To create a circle tangent to existing objects

1 From the Draw menu, choose Circle ➤ Tan, Tan, Radius.

You are now in Tangent snap mode.

2 Select the first object to draw the circle tangent to.

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center, radius two points defining diameter

three points defining circumference

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3 Select the second object to draw the circle tangent to.

4 Specify the radius of the circle.

To create a circle tangent at two or three points, set OSNAP to Tangent and use the two-point or three-point method to create the circle (see “Snapping to Points on Objects” on page 167).

Drawing Arcs

You can create arcs in many ways. The default method is to specify three points—a start point, a second point on the arc, and an endpoint. You can also specify the included angle, radius, direction, and chord length of arcs. The chord of an arc is a straight line between the endpoints. By default, AutoCAD draws arcs counterclockwise.

In the following example, the start point of the arc snaps to the endpoint of a line. The second point of the arc snaps to the middle circle.

To draw an arc by specifying three points

1 From the Draw menu, choose Arc ➤ Start, Center, End.

2 Specify the start point (1) by entering endp and selecting the line.

The arc snaps to the endpoint of the line.

3 Specify the second point (2) by entering cen and selecting the existing arc to define the center of the arc.

4 Specify the endpoint of the arc (3).

Command line ARC

Related ELLIPSE creates elliptical arcs. PLINE creates arc segments within 2D polylines.

In the following illustrations, the center of an existing circle is used as the center of the arc. Once you specify the center and start points of the arc, you complete the arc by specifying the chord length. The distances shown in these illustrations from one endpoint to the cursor are chord lengths.

start (1), center,

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start (1), center (2), end (3)

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arc drawn using default 3-point method

endpoint of line


To draw an arc using a start point, a center point, and a chord length

1 From the Draw menu, choose Arc ➤ Start, Center, Length.

2 Specify a start point (1).

3 Specify the center point (2).

4 Specify the chord length.

■ Use the Start, Center, Angle or Center, Start, Angle method when you have a start point and a center point you can snap to. The angle determines the endpoint of the arc.

■ Use the Start, End, Angle method when you have both endpoints but no center point to snap to.

The following illustration on the left shows an arc drawn by specifying a start point, endpoint, and radius. You can specify the radius by entering a length or by moving the cursor away from the endpoint to specify a distance.

chord length

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The previous illustration on the right shows an arc drawn with the pointing device by specifying a start point and endpoint and a direction of the tan-gent. Moving the cursor up from the start point and endpoint draws the arc concave to the object, as shown here. Moving the cursor down would draw the arc convex to the object.

You can start a line at the endpoint of the last drawn arc by starting LINE and pressing ENTER at the Start Point prompt. The arc’s endpoint defines the start point and the tangential direction of the new line. You need to specify the length.

Drawing Spline Curves

A spline is a smooth curve passing through a given set of points. AutoCAD uses a particular type of spline known as a nonuniform rational B-spline (NURBS) curve. A NURBS curve produces a smooth curve between control points. Splines are useful for creating irregular-shaped curves, for example, drawing contour lines for geographic information system (GIS) applications or automobile design.

AutoCAD creates “true” splines—which are NURBS curves—with the SPLINE command. You can also create linear approximations of splines by smooth-ing polylines with PEDIT. You can convert 2D and 3D smoothed polylines to splines with SPLINE.

Creating true spline curves rather than editing polylines to approximate splines has three advantages:

■ Spline curves can be created by interpolating the spline through a set of points that lie on the desired path of the curve. This method creates curved boundaries far more accurately than polylines for both 2D drafting and 3D modeling.

arc endpoint resulting line

splines


■ Splines can be edited easily either with the SPLINEDIT command or with grips, and the spline definition is maintained. This definition is lost with PEDIT-smoothed polylines. See “Editing Splines” on page 298.

■ A drawing containing splines uses less disk space and memory than a drawing with smoothed polylines.

You create splines by specifying points. You can close the spline so the start point and endpoint are coincident and tangent. You can also change the spline-fitting tolerance while drawing the spline to see how closely the spline fits the set of specified fit points. The lower the tolerance, the more closely the spline fits the points. At zero tolerance, the spline passes through the points.

To create a spline by specifying points

1 From the Draw menu, choose Spline.

2 Specify the spline’s start point (1).

3 Specify points (2 through 5) to create the spline and press ENTER.

4 Specify the start and end tangents (6 and 7).

The following illustration shows the result when you use the same points but different start and end tangents.

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The following spline is drawn using the same points but a higher tolerance and different start and end tangents.

Command line SPLINE

Related SPLINEDIT edits a spline object. PLINE draws polyline line and arc segments that form a single object. PEDIT can modify a polyline into an approximation of a spline.

Drawing Ellipses

You can create full ellipses and elliptical arcs, both of which are exact math-ematical representations of ellipses. The default method of drawing an ellipse is to specify the endpoints of the first axis and the distance, which is half the length of the second axis. The longer axis of an ellipse is called the major axis, and the shorter one is the minor axis. The order in which you define the axes does not matter.

In the following procedure, you draw an ellipse using the default method and the pointing device. Here, the first axis is the major axis, and the second is the minor. The distance increases as you drag the pointing device away from the midpoint.

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To draw a true ellipse using endpoints and distance

1 From the Draw menu, choose Ellipse ➤ Axis, End.

2 Specify the first endpoint of the first axis (1).

3 Specify the second endpoint of the first axis (2).

4 Drag the pointing device away from the midpoint (3) of the first axis and click to specify the distance.

Command line ELLIPSE

You can provide a rotation angle instead of a distance or draw the ellipse based on a center point, an endpoint of one axis, and half the length of the other axis.

Ellipses created by specifying axis endpoints and distance

In the illustrations above, points 1 and 2 are the endpoints of the first axis, and point 3 defines the distance (half the length) of the second axis. The el-lipse at the left is drawn by specifying the center (1) and two axes. The end-point of the first axis is at point 2, and point 3 defines half the length of the second axis.

Drawing Elliptical ArcsThe default method of drawing elliptical arcs uses the first axis endpoints and the second axis distance, as for full ellipses. You then specify start and end angles. The apex of the angle is the center of the ellipse, and the major axis is defined as 0 degrees. The start angle defines the start point of the elliptical arc. The end angle defines the endpoint, and the arc is drawn between these points in the direction set by the ANGDIR system variable. If ANGDIR is 0, the angles are measured in a counterclockwise direction. If ANGDIR is 1, they are measured in a clockwise direction.

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cursor dragged to specify distance

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If the start and end angles are the same, you create a full ellipse. You can also specify a start angle and an included angle. The included angle is measured relative to the start point instead of from 0 degrees.

In the following procedure, start and end angles are measured from point 1, the first endpoint of the first axis, ANGDIR is set to 0, so the angles are measured counterclockwise from point 1. The start angle (4) is 230-degrees and the end angle (5) is 50-degrees.

To draw an elliptical arc using start and end angles

1 From the Draw menu, choose Ellipse ➤ Arc.

2 Specify endpoints for the first axis (1 and 2).

3 Specify the distance of the second axis (3).

4 Specify a start angle (4).

5 Specify an end angle (5).

Related ARC creates arcs. PLINE creates arc segments within polylines.

Drawing Isometric CirclesIf you are drawing on isometric planes to simulate three dimensions, you can use ellipses to represent circles viewed from an oblique angle. First you need to turn on an isometric plane (see “Setting Snap and Grid to Isometric Mode” on page 166).

To draw an isometric circle

1 Turn on the Isometric snap and grid.

2 From the Draw menu, choose Ellipse ➤ Axis, End.

3 Enter i (Isocircle).

4 Specify the center of the circle (1).

5 Specify the radius or diameter of the circle (2).

Drawing Donuts

Drawing donuts is a quick way to create filled rings or solid-filled circles. Donuts are actually closed polylines that have width. To create a donut, specify its inside and outside diameters and its center. You can continue

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creating multiple copies with the same diameter by specifying different centers until you press ENTER to end the command. To create solid-filled circles, specify an inside diameter of 0.

Donuts created as filled rings and solid-filled circles

To draw a donut

1 From the Draw menu, choose Donut.

2 Specify the inside diameter (1).

3 Specify the outside diameter (2).

4 Specify the center of the donut (3).

5 Specify the center point for another donut or press ENTER to end the command.

Command line DONUT

System variables DONUTID stores the inside diameter value of a donut; DONUTOD stores the outside diameter value. FILLMODE controls the display of donuts and other wide polylines.

Related PEDIT edits donuts. EXPLODE converts a donut to two arcs. If you explode a donut, its line width reverts to 0.

Creating Point Objects

Point objects can be useful, for example, as node or reference points that you can snap to and offset objects from. You can set the style of the point and its size relative to the screen or in absolute units.

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Changing the Drawing Order of Objects | 143

To set point style and size

1 From the Format menu, choose Point Style.

2 In the Point Style dialog box, select a point style.

3 Under Point Size, specify a size.

4 Choose OK.

Command line DDPTYPE

To create a point marker

1 From the Draw menu, choose Point ➤ Single Point.

2 Specify the point location.

Command line POINT

System variables PDMODE sets different point styles. PDSIZE controls point size.

Changing the Drawing Order of Objects

By default, objects are drawn in the order they are created. DRAWORDER changes the display order of objects, moving one in front of another, for example.

Ordering ensures proper display and plotting output when two or more objects overlay one another. An example of when ordering may be neces-sary is when a raster image is drawn over existing objects, obscuring them from view.

sets style

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To change the drawing order of an object

1 Select the objects whose drawing order you want to change.

2 From the Tools menu, choose Display Order.

3 Select Bring to Front or Send to Back to indicate the drawing order of the selected objects. Or, select Bring Above Object or Send Under Object to select the object you want to move above or below.

Command line DRAWORDER

Regenerating the Drawing Order

When you open a drawing previously saved with a specified drawing order, the display is regenerated based on the original order in which the objects were created. To display objects in the DRAWORDER command order, use the REGEN command. REGEN regenerates the display in the current viewport, but because it also regenerates the entire drawing, the screen coordinates for all objects are also regenerated.

The REDRAW command refreshes the display in the current viewport but does not recalculate the coordinates for all objects. REDRAW takes much less time than REGEN. For more information about REDRAW and REGEN, see “Refresh-ing the Screen Display” on page 64.

Setting the SORTENTS System Variable

The initial value for the SORTENTS system variable is 96, which means sorting is turned on only for plotting and PostScript output. By default, when you use the DRAWORDER command, object sorting is turned on for all sorting operations, and SORTENTS is automatically set to 127, which is the sum of all the bit-code values. For operations such as object selection and display re-draws, objects are displayed in the most efficient manner possible without adhering to a specific drawing order.

Changing SORTENTS may temporarily disable the display order of the objects you have just ordered. However, if you use DRAWORDER again, the drawing order is restored.

In large drawings, regeneration and redrawing can be slower when SORTENTS is on. Setting SORTENTS to 0 turns off the sort order, which means AutoCAD displays objects in the most efficient manner possible without adhering to a specific drawing order. For more information about SORTENTS and its code values, see the Command Reference.

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Creating Solid-Filled Areas

You can create triangular and quadrilateral areas filled with a color. For quicker results, create these areas with the FILLMODE system variable off, and then turn on FILLMODE to fill the finished area. You don’t see the area outline until it is complete.

Solid-filled areas used to depict buildings

To create a triangular solid-filled area

1 From the Draw menu, choose Surfaces ➤ 2D Solid.

2 Specify the first point (1).

3 Specify the second point (2).

4 Specify the third point (3). Then press ENTER.

5 Press ENTER again to exit the command.

When you create a quadrilateral solid-filled area, the sequence of the third and fourth points determines its shape. Compare the following illustrations:

Command line SOLID

Related 3DFACE creates a 3D face.

solid-filled areas

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3

1

3

1

4

1 2

34

2


Creating Regions

Regions are 2D enclosed areas you create from closed shapes called loops. A loop is a curve or a sequence of connected curves that defines an area on a plane with a boundary that does not intersect itself. Loops can be combina-tions of lines, polylines, circles, arcs, ellipses, elliptical arcs, splines, 3D faces, traces, and solids. The objects that make up the loops must either be closed or form closed areas by sharing endpoints with other objects. The objects must also be coplanar (on the same plane).

You can create regions out of multiple loops and out of open curves whose endpoints are connected and form loops. If the open curves intersect in their interior, they cannot form a region. Objects such as 3D polylines and face meshes can be converted to regions by being exploded. You cannot form regions from open objects that intersect to form a closed area: for example, intersecting arcs or self-intersecting curves.

You can apply hatching and shading to regions, and you can analyze proper-ties such as their area and moments of inertia.

To create regions by selecting objects

1 From the Draw menu, choose Region.

2 Select objects to create the region (must be closed loops).

3 Press ENTER.

A message on the command line indicates how many loops were detected and how many regions were created.

Command line REGION

Related BOUNDARY creates regions by first creating polyline boundaries from intersecting objects, whether they share endpoints or not. BHATCH creates an associative hatch boundary. BLOCK creates a compound object (a block definition) from a group of objects.

To create regions by using boundaries

1 From the Draw menu, choose Boundary.

2 In the Boundary Creation dialog box under Object Type, select Region.

3 If you want to limit the number of objects that AutoCAD analyzes when you use Pick Points to create boundaries (by default, AutoCAD analyzes all objects visible in the current viewport), under Boundary Set, choose the New button.

basic shapes that can form regions

Creating Regions | 147

4 Select the objects that you want AutoCAD to analyze when you define boundaries and press ENTER.

5 Choose Pick Points.

6 Specify a point in your drawing inside each area that you want to be defined as a region and press ENTER.

Command line BOUNDARY

Related REGION creates a region object from a selection set of existing objects. BHATCH fills an enclosed area or selected objects with a hatch pattern.

You can create composite regions by subtracting, combining, or finding the intersection of regions. You can then extrude or revolve composite regions to create complex solids (see chapter 17, “Working in Three-Dimensional Space”).

When you subtract one region from another, you first select the region from which you want to subtract. For example, to calculate how much carpeting is needed for a floor plan, select the outer boundary of the floor space and subtract all the uncarpeted areas, such as pillars and counters. Find the area of the resulting region with the AREA command.

To create a composite region by subtraction

1 From the Modify menu, choose Solids Editing ➤ Subtract.

2 Select the region from which to subtract (1) and press ENTER.

3 Select the region to subtract (2).

Command line SUBTRACT

Related UNION and INTERSECT also create composite regions.

You can select regions in any order to unite them with the UNION command or to find their intersection with the INTERSECT command. AutoCAD ignores objects within the selection set that are not regions.

region

internal point

selected regions result—a composite region

1

2


The following illustration shows the uniting of two regions.

The following illustration shows the intersection of three regions, which you find using the INTERSECT command.

You can select in any order the regions whose intersection you want to find. The resulting object is also a region.

Hatching Areas

Hatching fills a specified area in a drawing with a pattern. You can hatch an enclosed area or a specified boundary using the BHATCH and HATCH commands.

BHATCH creates associative or nonassociative hatches. Associative hatches are linked to their boundaries and are updated when the boundaries are modi-fied. Nonassociative hatches are independent of their boundaries. BHATCH defines boundaries automatically when you specify a point within the area to be hatched. Any whole or partial objects that are not part of the boundary are ignored and do not affect the hatch. The boundary can have overhanging edges and islands (enclosed areas within the hatch area) that you choose to hatch or leave unhatched. You can also define a boundary by selecting objects.

selected regions result

resultselected intersecting regions

islands

overhanging edges

Hatching Areas | 149

HATCH creates nonassociative hatches only. It is useful for hatching areas that do not have closed boundaries. See “Creating a Hatch Using Point Acquisition” on page 150. HATCH is available only on the command line.

After you’ve created a hatch, you can edit it with HATCHEDIT or explode it into composite lines using the EXPLODE command.

Creating an Associative Hatch

Hatched areas created with BHATCH are associative by default. You can re-move hatch associativity at any time or you can change the default to create a nonassociative hatch. If you specify points to create an associative hatch, specify only one internal point per hatch block placement. Specifying more than one internal point can produce unexpected results when you edit the hatch boundary.

To hatch an enclosed area

1 From the Draw menu, choose Hatch.

2 In the Boundary Hatch dialog box, choose Pick Points.

3 Specify a point in your drawing inside each area you want to hatch. If you make a mistake, you can right-click and choose Clear All or Undo Last Select/Pick from the shortcut menu.

4 To preview the hatch, right-click and choose Preview.

5 Press ENTER to return to the Boundary Hatch dialog box.

6 Choose OK to apply the hatch.

By default, AutoCAD uses the Flood island detection method to define boundaries from the specified points, and the Normal island detection style to apply the hatch. See “Defining Hatch Boundaries” on page 151 and “Using Island Detection Styles” on page 154.

hatched object result of editing boundary with associative hatch

result of editing boundary with nonassociative hatch


To hatch selected objects


2 In the Boundary Hatch dialog box, choose Select Objects.

3 Select the object or objects you want to hatch.

The objects need not form a closed boundary. You can also specify any islands by selecting objects within other selected objects. If you make a mistake, you can right-click and choose Clear All or Undo Last Select/Pick from the shortcut menu.


5 Press ENTER to return to the Boundary Hatch dialog box.


By default, AutoCAD uses the Normal island detection style to apply the hatch. See “Using Island Detection Styles” on page 154.

Command line BHATCH

Related HATCH creates a nonassociative hatch. BOUNDARY creates a polyline or region boundary.

NOTE Due to the large number of combinations of objects that can be hatched, editing hatched geometry can produce unexpected results. If an error occurs, delete the hatch object and rehatch.

Creating a Hatch Using Point Acquisition

You can define a hatch boundary by specifying points directly. For example, you may want to illustrate a pattern fill in a small section of a drawing, as shown in the following illustration.

points specified to define hatch boundary

result

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To define a boundary by point acquisition

1 On the command line, enter hatch.

2 Enter the name of the hatch pattern.

3 Specify the hatch pattern scale and angle.

4 At the Select Objects prompt, press ENTER, because you are specifying points and not selecting objects.

5 Using points to create a hatch boundary creates a polyline boundary. Enter y to retain the polyline boundary, or n to discard it after the hatching is completed.

6 Specify the points that define the boundary.

7 Enter c (Close) and press ENTER.

Defining Hatch Boundaries

Boundaries can be any combination of lines, arcs, circles, 2D polylines, ellipses, splines, blocks, and paper space viewports (see “Creating Floating Viewports” on page 530). Each boundary component must be at least partially within the current view.

When you use Pick Points to define boundaries, the way in which AutoCAD derives the boundary definition from the specified point depends on the specified boundary set and the island detection method.

Using Island Detection MethodsIsland detection methods specify whether to include objects within the outermost boundary as boundary objects when you are using Pick Points. These internal objects are known as islands. By default, AutoCAD uses the Flood island detection method. The Flood method includes islands as bound-ary objects, as shown in the following illustration. How AutoCAD hatches the detected islands depends on the island detection style (see “Using Island Detection Styles” on page 154). The following illustration uses the Normal island detection style, meaning that islands remain unhatched and islands within islands are hatched.


If you do not want to include islands as boundary objects when using Pick Points, use the Ray Casting island detection method. Ray Casting runs a line from the point you specify to the nearest object and then traces the boundary in a counterclockwise direction, thus excluding islands from boundary detection.

You can find these options on the Advanced tab of the Boundary Hatch dialog box.

When you define boundaries by selecting objects rather than specifying points, the island detection method has no effect on how AutoCAD derives the boundary definition.

Removing IslandsWhen you use Pick Points to define your boundaries, you can remove any detected islands from your boundary definition. In the following procedure, you remove islands so that the part is hatched as illustrated.

resultboundaries detected internal point selected

internal point

internal point

resultislands to remove (solid boundaries)

boundaries detected


To remove islands from the hatch area



3 Specify a point in your drawing inside the hatch area.

4 Press ENTER.

5 Choose Remove Islands.

6 Select the islands for removal (see the solid boundaries in the middle illustra-tion) and press ENTER.


Command line BHATCH

Using Boundary SetsWhen you use Pick Points to define your boundaries, AutoCAD analyzes all objects in the boundary set to derive the boundary definition. The boundary set is the set of objects that AutoCAD treats as eligible for analysis when de-fining boundaries from a specified point.

By default, the boundary set consists of all objects fully or partially visible in the current viewport. So, if 100 objects are currently visible, AutoCAD ana-lyzes all 100 objects when you specify a point, regardless of the location of that point. Analysis of all of these objects can be time-consuming in a com-plex drawing. To hatch a small area of a complex drawing, you can define a custom boundary set. When you specify a point within the boundary set, AutoCAD does not analyze objects not included in the boundary set. Bound-ary sets are also useful for applying different hatch styles in different sections of a drawing.

In the following example, you create a boundary set within a map before defining and hatching your boundary.

To define a boundary set in a complex drawing


2 In the Boundary Hatch dialog box, choose the Advanced tab.

3 In the Boundary Set section of the Advanced tab, choose Select New Bound-ary Set.


4 At the Select Objects prompt, select the objects you want to include in the boundary set (1) and press ENTER.


6 Specify the internal point (2) to define the boundary, and press ENTER.


Using Island Detection Styles

You can control how AutoCAD hatches islands detected as boundaries using the three island detection styles: Normal, Outer, and Ignore. You can find these styles on the Advanced tab of the Boundary Hatch dialog box. The styles are also available from a shortcut menu by right-clicking in the draw-ing area while selecting objects or specifying points from which to define your boundaries.

NOTE Do not confuse island detection styles (Normal, Outer, and Ignore), which control the treatment of boundary definitions, with island detection methods (Flood and Ray Casting), which control the creation of boundary definitions from a specified point.

The Normal style hatches inward from the outer boundary. If it encounters an internal intersection, it turns off hatching until it encounters another intersection. Thus, areas separated from the outside of the hatched area by an odd number of intersections are hatched, and areas separated by an even number are not. The Outer style hatches inward from the outer boundary and stops at the next boundary. The Ignore style hatches the entire enclosed area, ignoring internal boundaries.

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new boundary set internal point result

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Hatch styles

If a hatch line encounters a text, attribute, shape, trace, or solid-fill object, and if the object is selected as part of the defined boundary, AutoCAD does not hatch through the object. You can draw a pie slice, for example, label it with text, and hatch it, and the text remains readable. If you want to hatch through such objects, use the Ignore style.

You cannot hatch the interiors of traces and solids because AutoCAD does not accept their outlines as boundaries.

Using Hatch Patterns

AutoCAD supplies a solid fill and more than 50 industry-standard hatch patterns that you can use to differentiate the components of objects or represent object materials. AutoCAD supplies 14 hatch patterns that conform to the ISO (International Standardization Organization) standards. When you select an ISO pattern, you can specify a pen width, which determines the lineweight in the pattern.

You can use a pattern supplied with AutoCAD or one from an external pat-tern library. For a table of the hatch patterns supplied with AutoCAD, see appendix E, “Standard Libraries,” in the Command Reference.

You can also define your own hatch pattern using the current linetype with the User Defined Pattern option, or you can create more complex hatch patterns. For information about creating hatch patterns, see chapter 2, “Line-types and Hatch Patterns,” in the Customization Guide. To reduce file size, a hatch pattern is defined in the drawing database as a single graphical object.

Normal Outer Ignore

default hatching of text

industry-standard hatch patterns


In the first procedure that follows, you use the Hatch Pattern Palette dialog box to choose an ISO pattern. In the second procedure, you create a simple line pattern by defining the spacing between the lines and creating a second set of lines at 90 degrees to the original lines.

To use an ISO hatch pattern


2 In the Boundary Hatch dialog box, choose the Quick tab.

3 Under Type, choose Predefined.

4 Under Pattern, choose an ISO pattern name from the list, or if you prefer to choose the pattern by viewing preview images, choose the [...] button next to the Pattern list.

5 In the Hatch Pattern Palette dialog box, choose the ISO tab.

6 Choose a pattern and choose OK.


8 Specify an internal point and press ENTER.


If the pattern is not displayed the way you want, you may need to adjust the pattern, scale, or angle. Use the Preview button in the Boundary Hatch dialog box to preview the hatch with the new settings.

10 Press ENTER to return to the Boundary Hatch dialog box. Choose OK to apply the hatch.

To define a hatch pattern


2 In the Boundary Hatch dialog box, choose the Quick tab.

3 Under Type, choose User Defined.

4 Under Spacing, enter the spacing between lines.

5 Select Double to add lines at 90 degrees to the original.

6 Choose Pick Points.

7 Specify an internal point and press ENTER.


Command line BHATCH

Custom and Proxy Objects | 157

Custom and Proxy Objects

Many software vendors other than Autodesk use the AutoCAD Runtime Extension programming language to write programs that create graphical and nongraphical objects you can insert into AutoCAD drawings. Objects created by ObjectARX™applications are called custom objects. To display and use custom objects in AutoCAD drawings, the ObjectARX application that created them must be available to AutoCAD. If not, AutoCAD temporarily replaces the custom object with a proxy object. Later, when the application is available to AutoCAD, the proxy object is replaced by the custom object.

You encounter proxy objects when

■ You open a drawing containing custom objects, but the application that created them is not installed on your system

■ You unload the ObjectARX application that created the custom object in the current drawing

AutoCAD displays the Proxy Information dialog box when proxy objects are displayed. The dialog box tells you the total number of proxy objects in the drawing (both graphical and nongraphical) and the name of the missing application and provides additional information about the proxy object type and display state. You can use the dialog box to control the display of proxy objects.

Working with Named Objects

AutoCAD drawing files contain both graphical and nongraphical objects. You use graphical objects, such as lines, arcs, and circles, to create your designs. At the same time, you use nongraphical information, called named objects, to manage the design. Named objects include such items as text styles, dimension styles, named layers, and named views. Named objects help you design more efficiently. For example, if you use a set of linetype properties frequently, you can save the properties as a named linetype and then apply the linetype to lines in your drawing at any later time.

You can define and save different ways to view a drawing. For example, you can save multiple UCSs (user coordinate system), so you can easily switch from one UCS to another during a drawing session. You can also save multi-ple views and viewport configurations.


AutoCAD stores named objects in symbol tables and data dictionaries. Each kind of named object has a symbol table, or a dictionary, and each table or dictionary can store multiple named objects. For example, if you create 10 dimension styles, your drawing’s dimension style symbol table will have 10 dimension style records. However, unless you create LISP routines or pro-gram AutoCAD, you do not work with symbol tables or dictionaries directly. You can view and revise all named objects using AutoCAD dialog boxes or the command line. The following table shows AutoCAD named objects.

AutoCAD named objects

Named object Description

Block Contains the block name, base point, and component objects.

Dimension style Stores dimension settings that control the appearance of a dimension.

Group Defines a selection set of objects.

Layer Organizes graphical data in the same way that transparent acetate overlays on a drawing do; the layer symbol table stores the properties that you set for it, such as color and linetype.

Layout Defines the environment in which you create and design paper space floating viewports to be plotted.

Linetype Stores information that controls how a line or curve is displayed, for example, whether the line is continuous or dashed.

Multiline style Defines styles for multiline properties.

Plot settings Defines page setup information for plotting.

Plot style Defines an object property that specifies a set of overrides for color, dithering, gray scale, pen assignments, screening, linetype, lineweight, endstyles, join-styles, and fill styles. Plot styles are assigned when the drawing is plotted.

Text style Stores settings that control the appearance of text characters, for example, stretched, compressed, oblique, mirrored, or set in a vertical column.

UCS Stores the position of the X, Y, and Z axes and the location of the origin. This defines the coordinate system in a drawing.

View Stores the graphical representation of a model from a specific location (viewpoint) in space.

Viewport configuration Stores an arrangement of tiled viewports.

Working with Named Objects | 159

Naming Named Objects

You can create named object names up to 255 characters long. In addition to letters and numbers, names can contain spaces (although AutoCAD removes spaces that appear directly before and after a name) and any special character not used by Microsoft® Windows® or AutoCAD for other purposes. Special characters that you cannot use include less-than and greater-than symbols (< >), forward slashes and backslashes (/ \), quotation marks (“), colons (:), semicolons (;), question marks (?), commas (,), asterisks ( *), vertical bars (|), equal signs (=), and backquotes (‘). You also cannot use special characters created with Unicode fonts.

NOTE In previous AutoCAD releases, object names are limited to 31 charac-ters. If you save an AutoCAD 2000 drawing in the format of a previous release, AutoCAD replaces any illegal characters with underscores ( _ ) and shortens the name to 31 characters. AutoCAD preserves the long name and restores it when you open it in AutoCAD 2000. However, if the name is changed by an earlier AutoCAD version, the long name is lost.

Renaming Named Objects

As your drawings become more complex, you can rename named objects to keep the names meaningful or to avoid conflicts with names in drawings you insert into the main drawing. You can rename any named object except those that AutoCAD names by default, for example, layer 0.

To rename a named object

1 From the Format menu, choose Rename.

2 In the Rename dialog box under Named Objects, select the object type.

3 Select the named object from the Items list, or enter the name in Old Name.

4 In Rename To, enter the new name, and then choose Rename To.

5 Choose OK.

Command line RENAME

Renaming Xref Objects

To rename named objects brought into your drawing through external references (xrefs) you must first bind the xref to the drawing. Cross-referenced named objects are displayed in the format XREF NAME|OBJECT NAME. For example, suppose you have a drawing called FIRST FLOOR with


an ELECTRICAL layer. If you insert FIRST FLOOR into another drawing, for example, BUILDING, the ELECTRICAL layer is displayed in the BUILDING layers list as FIRST FLOOR|ELECTRICAL.

To rename the FIRST FLOOR|ELECTRICAL layer, you must bind FIRST FLOOR to the BUILDING drawing (see “Binding Xrefs” on page 469). AutoCAD replaces the vertical bar (|) with two dollar signs ($) separated by a number (usually zero): for example, FIRST FLOOR$0$ELECTRICAL, and makes it available for you to rename.

Using Wild-card Characters

You can use wild-card characters to rename groups of named objects. For example, to rename the group of layers STAIR$LEVEL-1, STAIR$LEVEL-2, STAIR$LEVEL-3 to S_LEVEL-1, S_LEVEL-2, S_LEVEL-3, enter stair$* under Old Name and s_* under Rename To. The following table shows the wild-card characters that you can use.

Valid wild-card characters

Character Definition

# (Pound) Matches any numeric digit

@ (At) Matches any alphabetic character

. (Period) Matches any nonalphanumeric character

* (Asterisk) Matches any string and can be used anywhere in the search string

? (Question mark) Matches any single character, for example, ?BC matches ABC, 3BC, and so on

~ (Tilde) Matches anything but the pattern, for example, ~*AB* matches all strings that don’t contain AB

[ ] Matches any one of the characters enclosed, for example, [AB]C matches AC and BC

[~] Matches any character not enclosed, for example, [~AB]C matches XC but not AC

[-] (Hyphen) Specifies a range for a single character; for example, [A-G]C matches AC, BC, and so on to GC, but not HC

‘ (Reverse quote) Reads next character literally, for example, ‘*AB matches *AB

Working with Named Objects | 161

NOTE If you use wild-card characters in named object names, precede the character with a backquote (‘ ) so AutoCAD does not interpret the character as a wild-card character.

Purging Named Objects

Over time, drawings may accumulate many named objects that are no longer needed. For example, you may have a text style that is no longer used by any drawing text, or a layer that contains no drawing objects.

Purging named objects reduces drawing size. You can purge individual named objects, all styles and definitions of a specific type, or all named objects in a drawing. Keep in mind, however, that you cannot purge named objects that are referenced by drawing objects. For example, you cannot purge a linetype used by a line in your drawing.

Purging removes only one level. For example, if purging a layer removes the only reference to a linetype, the linetype is not purged until you purge again using the Linetype option.

To purge unused named objects

1 From the File menu, choose Drawing Utilities ➤ Purge.

2 Choose an object type to purge, or choose All to purge all unused named objects.

AutoCAD prompts you with the name of each unused named object of the specified type.

3 Enter the named object to be purged or enter an asterisk (*) for All.

4 Enter y or n to verify each name to be purged.

If you answer y, AutoCAD displays the named object’s symbol table reference and name.

5 Enter y or n in response to each prompt. The command ends when AutoCAD finds no unused named objects.

Command line PURGE

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