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Chapter

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Drawing ObjectsChapter 1:

Using the tools discussed in this chapter, you learn to create and manipulate additional types of AutoCAD® objects and tools for markup and revision.

Objectives

After completing this chapter, you will be able to:

■ Create and edit multiline styles and multiline objects. ■ Create revision clouds. ■ Create wipeout objects in a drawing. ■ Create boundaries by using the Boundary command. ■ Create regions in a drawing using the Region and Boundary commands.

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2 ■ Chapter 1: Drawing Objects

Lesson: Creating and Editing Multilines

Overview

This lesson describes how to create and edit multiline styles and multiline objects.

Multilines are objects that contain multiple parallel lines. Multilines are convenient when you want to draw objects such as walls in floor plans because walls are often represented by two or more parallel lines. Each element of a multiline is defined, in part, by its distance or offset from a center, where the center is considered zero offset.

Multiline objects save time wherever you need to create parallel lines in the drawing.

The following illustration displays multiline objects used to depict walls in the outline of a simple floor plan.

Objectives

After completing this lesson, you will be able to:

■ Describe multiline objects. ■ Describe multiline styles. ■ Identify the various options of the Mline command. ■ Create multiline objects. ■ Edit multiline objects.

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Lesson: Creating and Editing Multilines ■ 3

About Multiline Objects

Multilines consist of 1 to 16 parallel lines, called elements. The default multiline style has just two elements but you can create additional styles of an endless variety. The Multiline Style command enables you to create new multiline styles by adding line elements, changing the color and linetype of elements, adding end caps and the option of displaying the object as a solid color.

Definition of Multiline Objects

A multiline object is a special type of line that consists of several parallel lines grouped into a single multiline object. Each line in the multiline object is considered a multiline element and has individual properties such as offset value, linetype, and color.

Example of a Multiline Objects

The following illustration shows a multiline with two parallel elements used to represent a wall object.

The following illustration shows a multiline with three parallel elements used to represent pipe line details.

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The following illustration shows multiline used to represent a three phase wire in electrical designs.

About Multiline Styles

You create multiline objects based on properties of the existing multiline style. All drawings contain a default multiline style called Standard. This style is assigned to all multiline objects created in the drawing unless you specify a custom style.

It is important to understand how to create and apply multiline styles before you create multilines, because after you have assigned a multiline to a style and then created the multiline, there is no way to assign it to a different style.

Definition of Multiline Styles

Multiline styles are objects with element and multiline properties and are stored in the drawing. These objects can then be used with the Multiline command.

Multiline Style Dialog Box

You use the Multiline Style dialog box to create, modify, delete, and manage multiline styles. You can resize the Multiline Style dialog box to provide better preview capability. Drag the lower-right corner to expand the dialog box and the preview window.

Command Access

Multiline Style

Command Line: MLSTYLE

Menu: Format > Multiline Style

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The following illustration shows the Multiline Style dialog box.

The following describes the options in the Multiline Style dialog box:

Create New Multiline Style Dialog Box

When you select the New option in the Multiline Styles dialog box, the Create New Multiline Style dialog box appears. In this dialog box, you give a name to the new style and select an existing style on which to base the new style.

The following illustration shows the Create New Multiline Style dialog box.

Load and Save To load or save multiline styles, which are stored in *.mln files.

Preview window To preview the selected multiline style.

Set Current To set the selected style as the current style.

New Style Name To name the new multiline style.

Start With To determine the multiline style from which to start the new style. The new style begins with the same properties as the style you select.

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Modify Multiline Style Dialog Box

You create and modify multiline styles in either the New Multiline Style dialog box or the Modify Multiline Style dialog box. Both dialog boxes are identical in functionality.

The following illustration shows the Modify Multiline Style dialog box.

Description To enter a description for the multiline style.

Caps To cap the multilines at their start and endpoints.

Elements To add, delete, and modify multiline elements.

Fill To select a fill color for the linetypes or use the default selection. The default selection is None.

Display Joints To display a line across the multiline elements as it changes direction.

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Example of Multiline Styles

The following illustration shows various multiline style properties being used.

Key Points

■ The default multiline style in all drawings is Standard.■ The current multiline style is used by default when you create multilines.■ Use the Load and Save options to make custom multiline styles available to other workstations.■ You cannot edit the element and multiline properties of any multiline style already used in

the drawing.

Outer arc cap Line type

Line cap Display Joints

Inner arc cap Fill

Multiline Styles in UseEnsure that you test the multiline style before you create multiline geometry. Once you assign a multiline to a style, you cannot modify the multiline style. Nor can you rename or delete a multiline style if it is referenced by a multiline object in the drawing.

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Multiline Command

You create multiline objects with the Multiline (Mline) command. When you start the Mline command, you are given the option to set the justification, scale, and style of the multiline. After you set these options, you draw multilines in the same way you create standard lines. You specify a start point, and then continue to specify next points for the multiline, as required.

Command Access

Command Options

The Multiline command offers the following options:

Multiline

Command Line: MLINE

Menu: Draw > Multiline

Option Description

Justification Enter a justification option:■ Top

The cursor is aligned with the upper multiline element when you are drawing in the 0 degree direction.

■ Zero

The cursor is aligned with the multiline element containing a zero offset. ■ Bottom

The cursor is aligned with the bottom multiline element when you are drawing in the 0 degree direction.

Scale Enter a scale factor for the multiline. All multiline style parameters are scaled by this value.

Style Enter a multiline style.

You can break a multiline object into its component elements by using the Explode command. If the multiline object uses a fill color, the fill is removed.

Multiline Scale in Metric DrawingsWhen you create multilines in metric drawings, be sure to adjust the scale option appropriately. By default, the multiline scale in metric drawings is set to 20. If you intend a value of 1 in the multiline style to be equal to 1mm, then set the multiline scale to 1 when you create the multiline object.

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Creating Multiline Objects

You create multiline objects by using the Multiline command.

Procedure: Creating Multiline Objects

The following steps describe how to create multiline objects.

1. Start the Mline command.

2. Confirm or change the current justification, scale, or style.

3. Specify a start point for the multiline object.

4. Specify the next point for the multiline object.

5. Continue to specify points for the multiline object.

6. Verify that the multiline object is created.

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Editing Multiline Objects

Multilines require special editing tools. You use the Trim and Extend commands to trim or extend the multilines. However, for other editing tasks you need to use the Multilines Edit Tools dialog box.

In the following illustration, the Delete Vertex multilines edit tool is being used to delete the vertices of the multiline to straighten it.

Multilines Edit Tools Dialog Box

Select the appropriate tool in the Multilines Edit Tools dialog box to edit the selected multiline. After you select the tool, the dialog box disappears and you are prompted to select the multiline.

Command Access

The following illustration shows the Multilines Edit Tools dialog box.

Multiline Edit

Command Line: MLEDIT

Menu: Modify > Object > Multiline

Drawing area: Double-click a multiline object.

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Options Description

Closed Cross To create a closed-cross intersection between two multilines.

Open Cross To create an open-cross intersection between two multilines. Breaks are inserted in all elements of the first multiline and only the outside elements of the second multiline.

Merged Cross To create a merged-cross intersection between two multilines. The order in which you select the multilines is not important.

Closed Tree To create a closed-tree intersection between two multilines. The first multiline is trimmed or extended to its intersection with the second multiline.

Open Tree To create an open-tree intersection between two multilines. The first multiline is trimmed or extended to its intersection with the second multiline.

Merged Tree To create a merged-tree intersection between two multilines.The multiline is trimmed or extended to its intersection with the other multiline.

Corner Joint To create a corner joint between multilines. The multilines are trimmed or extended to their intersection.

Add Vertex To add a vertex to a multiline.

Delete Vertex To delete a vertex from a multiline.

Cut Single To create a visual break in a selected element of a multiline.

Cut All To create a visual break through the entire multiline.

Weld All To rejoin multiline segments that has been cut.

Even if you double-click a multiline to display the Multilines Edit Tools dialog box, you are still required to select the multiline after you select the tool.

Trimming Multilines with the Trim CommandYou can trim a multiline object with the Trim command, but the fence object must cross all elements of the multiline object. You cannot trim only some elements.

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Procedure: Editing Multiline Objects

The following steps describe how to edit multiline objects with the Mledit command.

1. Start the Mledit command.

2. Select a multiline edit tool in the dialog box.

3. Select the multiline according to the prompts.

4. Continue selecting multilines to perform the same edit or press ENTER to exit the Mledit command.

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Exercise: Create and Edit Multilines

In this exercise, you create a new multiline style and create a multiline. You then use Trim and Extend, as well as the Multilines Edit Tools dialog box to edit the multiline.

Scenario

You want to draw the walls in a floor plan with two or more parallel lines showing wall thickness and center line. You decide to use the multiline command to perform your task.

You do the following:

■ Create a new multiline style.■ Edit the multiline.

Create New Multiline Styles

The completed exercise

Completing the ExerciseTo complete the exercise, follow the steps in this book or in the onscreen exercise. In the onscreen list of chapters and exercises, click Chapter 1: Drawing Objects. Click Exercise: Create and Edit Multilines.

1. Open c_create_edit_multilines.dwg.

2. Click Format menu > Multiline Style.

■ In the Multiline Style dialog box, click New.■ In the Create New Multiline Style dialog

box, enter Ext-Wall in the New Style Name field.

■ Click Continue.

3. In the New Multiline Style dialog box, enter Exterior Wall in the Description field.

■ Under Caps, verify that the Line Start and End checkboxes are selected.

■ Under Elements, click Add. Enter -5 in the Offset field.

■ Click Add again. Enter -9 in the Offset field, and click OK.

4. In the Multiline Style dialog box:

■ Ensure that the Ext-Wall style is selected.■ Click Set Current.■ Click OK to close the dialog box.

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5. On the status bar, right-click Osnap. Click Settings. In the Drafting Settings dialog box, ensure that the Node object snap is selected. Click OK to close the Drafting Settings dialog box.

6. Click Draw menu > Multiline and begin selecting points using the Node object snap.

■ Start with a point in the upper-left and continue counterclockwise.

■ When you are on the last segment of the multiline, right-click anywhere in the drawing.

■ Click Close.

7. Click Modify menu > Extend. Select the multiline object as shown.

Press ENTER.

8. Select the interior multiline object.

Press ENTER to specify the merged option.

9. Select the interior multiline near the point shown in the following illustration.

Press ENTER to specify the merged option.

10. Press ESC to exit the Extend command. Verify that the interior multiline has extended and merged with the exterior multiline.

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Edit Multilines

1. On the dashboard, Layers control panel, expand the Filter Applied list. Thaw the Trim layer.

2. On the dashboard, 2D Draw control panel, click Trim.

■ Select the six lines on the Trim layer.

■ Press ENTER.

3. Click the multiline at points between the trim lines.

Press ESC to end the Trim command.

4. On the dashboard, Layers control panel, expand the Filter Applied list. Freeze the Points and Trim layers.

5. Notice that the multilines are capped where they are trimmed.

6. Double-click the exterior wall multiline to start the Mledit command.

In the Multilines Edit Tools dialog box, select Delete Vertex.

7. Select the multiline near the point indicated.

8. Select the multiline near the point indicated.

Press ESC to exit the Mledit command.

9. Double-click the exterior wall multiline to start the Mledit command.

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10. In the Multilines Edit Tools dialog box, select Add Vertex.

11. Select the multiline near the point indicated to add a new vertex.

Press ESC to exit the Mledit command.

12. Select the multiline, you will see new vertex is added as shown.

13. Drag the newly added vertex grip and place it.

14. Close all files without saving.

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Lesson: Creating Revision Clouds ■ 17

Lesson: Creating Revision Clouds

Overview

This lesson describes how to create revision clouds.

You use revision cloud objects to highlight areas in the drawing that have been revised.

In the following illustration, a revision has been made to two dimensions. The dimensions and the area of change are highlighted by revision clouds.

Objectives


■ Identify the options of the Revcloud command. ■ Create revision clouds in the drawing. ■ Control the shape of revcloud using the Arc length option or predrawn objects.

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Revision Cloud Command Options

Revision clouds highlight changes in a design or mark up drawings. You use the Revcloud command to draw revision clouds in drawings. Alternatively, you can convert an existing closed polyline, circle, ellipse, or closed spline to a revision cloud by using the Object option.

You can change the appearance of revision clouds by adjusting the Arc Length option and changing the Style option from Normal to Calligraphy.

The following illustration shows a change in the diameter of a shaft being highlighted using a revision cloud.

Command Access

Revcloud

Command Line: REVCLOUD

Menu: Draw > Revision Cloud

Dashboard:

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Command Options

The Revcloud command has the following options.

Key Points for Creating Revision Clouds

■ Use the Revcloud command to draw revision clouds in drawings.■ Use the Object option to convert existing closed objects to revision clouds.■ The Revcloud command has three options: Arc Length, Object, and Style.

Creating Revision Clouds

You create a revision cloud by selecting a start point in the drawing, then moving the cursor around the area to be highlighted, and ending close to the start point. The revision cloud closes itself as the cursor approaches the start point.

Guidelines for Creating Revision Cloud

■ When you draw a revision cloud, you can vary the size of the arcs by using pick points for the smaller arc segments.

■ You can also edit the individual arc lengths and chord lengths of a revision cloud by adjusting the pick points or by moving the individual grips.

■ Revision cloud can be drawn in Normal or Calligraphy style.■ Revcloud is not designed to support transparent and real time panning and zooming.

Option Description

Arc Length Enter a minimum and maximum arc length for the arc segments that make up the revision cloud.

Object Convert an existing object to a revision cloud.

Style Select either Normal or Calligraphy:

■ Normal creates a revision cloud using polyline arc segments with a consistent start and ending width.

■ Calligraphy creates a revision cloud using polyline arc segments with varying start and ending widths. This gives the revision cloud a hand-drawn appearance.

After you start the Revcloud command, check the current settings on the command line. This will help you change the current settings as required to create the Revcloud.

Minimum arc length: 15 Maximum arc length: 15 Style: Calligraphy

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Procedure: Creating Revision Cloud

The following steps describe how to create a revision cloud.

1. Start the Revcloud command from the 2D Draw control panel of the Dashboard.

2. Confirm the current settings for Arc length and Style.

3. Specify a start point for the revision cloud and then begin moving the cursor around the area you want highlighted by the revision cloud.

4. Return to the area near the start point. The revision cloud closes itself.

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Exercise: Create Revision Clouds

In this exercise, to highlight the changes in areas of the drawing, you create revision clouds using the Revcloud command. Additionally, you control the shape of the revision cloud using the Arc Length, Calligraphy and Object options.

Scenario

You are making dimensional adjustments for weight control in unmachined areas in a shaft. You need to highlight the changes you have made to the design. You decide to use the Revcloud command to create revision clouds.


Completing the ExerciseTo complete the exercise, follow the steps in this book or in the onscreen exercise. In the onscreen list of chapters and exercises, click Chapter 1: Drawing Objects. Click Exercise: Create Revision Clouds.

1. Open c_create_revision_clouds.dwg.

2. Zoom into the view on the right side of the drawing.

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3. On the 2D Draw control panel of the Dashboard, click Stretch.

4. Click two points to define the crossing window as shown and press ENTER.

5. Click near first point and enter 5<180.

6. On the 2D Draw control panel, click Revision Cloud.

7. With the Revcloud command activated, verify that the command line has the following settings:

■ Minimum arc length: 5.0000■ Maximum arc length: 5.0000■ Style: Normal

TIP: If any options are different, right-click anywhere in the drawing and use the Arc Length option to modify the arc length. After modifying the arc length right-click anywhere in the drawing again and use Style option to adjust the style.

8. Towards the right of the drawing, click near the top of the dimension as shown.

9. Move the crosshairs around the area until you return to the point where you started. When you get close enough to the start point, the revision cloud closes itself.

10. On the 2D Draw control panel, click Rectangle.

11. With the Rectangle command activated create a rectangle around the dimension as shown.

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12. On the 2D Draw control panel, click Revision Cloud.

13. With the Revcloud command activated, right-click anywhere in the drawing and click Style. Right-click anywhere in the drawing again and click Calligraphy.

■ Press ENTER to use the Object option.■ Select the rectangle object around the

dimension and press ENTER.

14. In the drawing area, after selecting the first revision cloud you created, right-click anywhere in the drawing and click Polyline Edit.

15. In the Context Menu that opens,

■ Enter W.■ Enter 1 for the new width for all

segments.■ Press ENTER to exit the Pedit command.

16. Zoom out the drawing extents.


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Lesson: Creating Wipeout Objects

Overview

This lesson describes how to create wipeout objects in a drawing.

When you want to hide some details of the drawing, you can use the wipeout objects to blank out the existing objects. Wipeout objects use the current background color to hide the underlying objects.

The following illustration shows a wipeout object masking an area on the drawing so that the text VOID is easily read.

Objectives


■ Identify the options of the Wipeout command. ■ Create wipeout objects.

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Lesson: Creating Wipeout Objects ■ 25

Wipeout Command Options

You can use the Wipeout command during the revision stage of the drawing to emphasize which area of the drawing is revised. This would help the drawing reviewer to get the alerts on drawing changes. With the help of the Wipeout command you can create Wipeout objects that enable you to work more efficiently by providing clear space for adding text. The geometry covered by the wipeout object is not erased; it is only hidden from the view. You can revise the shape and size of the wipeout object, as required. When you edit the shape of the wipeout object, underlying objects are hidden or become visible on the drawing, depending on where the wipeout frame gets moved to.

You can mask objects either by creating a polygonal area around the objects using a series of points, or by converting an existing closed polyline to a wipeout object. The boundary of the wipeout object is known as the wipeout frame. The wipeout frame determines whether the boundary of the wipeout object used in the drawing is displayed or hidden.

In the following illustration, a large portion of the drawing is masked with the wipeout object to cover the obsolete design geometry.

Command Access

Wipeout object

Wipeout frame

Wipeout

Command Line: WIPEOUT

Menu: Draw > Wipeout

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Command Options

The Wipeout command has the following options:

Key Points

■ All objects or portions of objects covered by a wipeout object are hidden.■ After you create the wipeout object, you can turn on the Frames wipeout option and use grips to

adjust the boundary of the wipeout object.■ The Frames option affects all wipeout objects in the drawing.

Option Description

Frames Turns wipeout frames on or off. You select and grip edit the wipeout boundary by turning the Frames option on. This option affects all wipeout objects in the drawing.

Polyline Converts a selected closed polyline to a wipeout object. To convert the polyline to a wipeout object, it is necessary that the polyline consists of only line segments, is closed, and has a zero width for all segments.

Placing Wipeout Objects on a LayoutWhen you print a drawing with a wipeout object, to ensure it prints correctly, clear the Plot Paperspace Last option in the Plot dialog box.

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Creating Wipeout Objects

You create wipeout objects to mask a portion of the drawing with current background color. You can also use wipeout objects to clear the background for notes on the drawing.

Procedure: Creating Wipeout Objects

The following steps describe how to draw and modify a wipeout object.

1. Start the Wipeout command.

2. Specify the first point for the boundary.

3. Continue to specify additional points. The boundary is drawn similar to the window polygon selection method.

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4. Complete specifying points for the boundary.

5. Select the wipeout frame and use the grips to modify the boundary to adjust the area affected by the wipeout object.

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Exercise: Create a Wipeout Object

In this exercise, you create a wipeout object to mask a large area on the drawing and mark it as void due to design changes.


■ Create a wipeout object.■ Mark the wipeout object as void.

Create a Wipeout Object


Completing the ExerciseTo complete the exercise, follow the steps in this book or in the onscreen exercise. In the onscreen list of chapters and exercises, click Chapter 1: Drawing Objects. Click Exercise: Create a Wipeout Object.

1. Open c_create_wipeout.dwg.

2. Click Draw menu > Wipeout.

■ Click to specify points, as highlighted in the following illustration.

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Mark the Wipeout Object as Void

3. Complete creating the wipeout object:

■ Right-click anywhere in the drawing to complete the selection.

■ Click Close.

■ Notice that the boundary closes itself.

1. On the Draw toolbar, click Multiline Text.

2. Double-click inside the wipeout object.

3. Select the formatting of the text to be entered. On the Text Formatting toolbar:

■ Select Arial as the font type.■ Enter 1.5 in the Text Height field.■ Click Bold.

4. On the Text Formatting toolbar:

■ Select Red from the color list.■ Select Center justification.■ Enter VOID in the in-place text editor.

■ Click OK.

5. Select the wipeout object to activate its grips.

■ Click and drag the grips to new locations to see the effect of adjusting the wipeout frame area.

■ Press ESC to clear the selection.

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6. Select the VOID text object with its center grip.

■ Right-click anywhere in the drawing.■ Click Rotate.■ Rotate the text object.

■ Press ESC to clear the selection.

7. To hide the boundary of the wipeout object:

■ Repeat the Wipeout command.■ Right-click anywhere in the drawing.

Click Frames.■ Right-click anywhere in the drawing.

Click Off.

8. Zoom to the drawing extents to view the full extent of the drawing after performing the Wipeout command.


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Lesson: Creating Boundaries

Overview

This lesson describes how to create boundaries by using the Boundary command.

You use the Boundary command to create polylines or regions around internal points you select in the drawing. In some cases, calculating the area defined by closed objects can be difficult. The Area command allows you to select geometric points to determine the area; if the area is made up of arcs or irregular shapes, selecting points to define the area will not be very accurate. The Boundary command can create polyline boundaries from which you can easily extract the exact area.

In the following illustration, the Boundary command is used to create group boundaries that simplify the process of determining lot areas.

Objectives


■ Identify the various options in the Boundary Creation dialog box. ■ Create boundaries.

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Lesson: Creating Boundaries ■ 33

Boundary Creation Dialog Box

You can use the Boundary command to create a region or polyline. The closed area of geometry that includes lines and arcs is defined as a polyline using Boundary command.

For example, in the following illustration the highlighted boundary is created by selecting a point near the LOT 2 text.

Boundary Command

You use the Boundary command to create polylines or regions around the closed areas formed from intersecting drawing geometry. You use the same pick point technique to create boundaries that you use for hatch patterns.

Command Access

Boundary

Command Line: Boundary

Menu: Draw > Boundary

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Boundary Creation Dialog Box

The following illustration shows the Boundary Creation dialog box.

Pick Points Click this option when you are ready to create boundaries by selecting points in the drawing. The dialog box closes and you are in point acquisition mode.

Island Detection Select this option to specify that the boundaries of closed objects within the area being bounded should be included as part of the boundary.

Object Type Select whether the boundary object should be a polyline or a region.

Boundary Set Change this option while working with large and complex drawings where examining everything on the screen becomes a time consuming process. The Boundary Set list has two options:

■ Current viewport

Leave this option selected to specify that boundaries can be calculated based on all geometry in the current viewport. Use this option for drawings without much geometry in them, otherwise boundary creation might be time-consuming.

■ Existing set

Click New, then manually select objects in the drawing using standard selection methods. Existing Set is automatically selected in the Boundary Set list. When you click Pick Points or OK, only the objects in the existing selection set are considered for the boundary calculations. For complex drawings, restricting boundary calculation to a subset of the current viewport’s geometry can speed up boundary calculation.

Consider using the Boundary command instead of the Pedit command to create a closed polyline by selecting each entity to convert and join to the polyline. In most cases, the Boundary command achieves the same result more quickly than Pedit.

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Island Detection

Turn island detection on to include any closed objects inside the overall boundary in the boundary calculation. Turn island detection off to ignore closed objects inside the overall boundary. The Island Detection option setting has implications when you use boundaries for calculations, for example for calculating area.

Island detection is turned on so the circles are detected when the boundary is calculated.

Island detection is turned off so the circles are not detected when the boundary is calculated.

If you are creating a boundary with island detection turned off, when you select the internal point, select a point closer to the outer boundary than to any islands. Selecting a point too close to an island generates an error that the point is outside of a boundary. The following dialog box appears. Click OK to reselect the point closer to the overall boundary, or click Look At It to see the boundary that is being calculated.

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Creating Boundaries

Boundary creates a polyline from an enclosed area. Creating boundaries is similar to creating hatch patterns, where you select a point inside an object or objects to calculate the boundary. However, when you use boundaries to define an area and its internal islands, you don’t have to apply hatch objects.

Procedure: Creating Boundaries

The following steps describe how to create boundaries.

1. Start the Boundary command.

2. Confirm or change the settings in the Boundary Creation dialog box. Click Pick Points.

3. Select one or more internal points in the drawing to calculate the boundaries. The boundaries are highlighted.

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4. The boundary objects are created on the current layer and you can select them as shown.

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Exercise: Create Boundaries

In this exercise, you use the Boundary command to make boundaries out of lots on a site plan. You then calculate the lot areas using the Area command, and notate the areas.

Scenario

You want to calculate the area of the closed region of the drawing. You decide to use the Boundary command to make the boundaries of the objects to make area calculation easier.


■ Create a boundary.■ Calculate lot areas.

Create Boundaries


Completing the ExerciseTo complete the exercise, follow the steps in this book or in the onscreen exercise. In the onscreen list of chapters and exercises, click Chapter 1: Drawing Objects. Click Exercise: Create Boundaries.

1. Open c_create_boundaries.dwg.

2. Zoom into the area around the right side of the site plan. Make sure all of the geometry around the seven lots is displayed in the drawing window. Notice that the current layer is set to Boundaries.

3. Click Draw menu > Boundary.

■ In the Boundary Creation dialog box, click Pick Points.

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Calculate Lot Areas4. On the drawing:

■ Select points near each lot label as shown. You can preview the boundaries.

■ Press ENTER to create the boundaries.

NOTE: When picking an internal point for the calculation of the boundary, the full area of the bounded shape must be visible in the drawing window. If any part of the geometry that should define the boundary is outside the drawing window, a valid hatch boundary will not be found.

1. Touch each boundary with the cursor. The new boundaries are highlighted.

2. Right-click any toolbar and select Inquiry to display the Inquiry toolbar.

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3. On the Inquiry toolbar, click Area. With the Area command activated:

■ Right-click anywhere in the drawing. Click Object.

■ Select the boundary around LOT 1.

4. Repeat the Area command on lots 2 through 7.

5. Zoom to the drawing extents.


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Lesson: Creating Regions ■ 41

Lesson: Creating Regions

Overview

This lesson describes how to create regions in a drawing using the Region and Boundary commands.

Regions are two-dimensional enclosed areas that have physical properties such as centroid. You can combine existing regions into a single, complex region to calculate area.

You can use regions to apply hatching, analyze properties such as area, and extract design information such as the centroid which is the center of mass.

You use the Region command to create regions based on closed objects that you can select. You use the Boundary command to create regions based on the calculation of a boundary around an internal point. The Region command deletes the original geometry, whereas the Boundary command creates the region and leaves the original geometry unchanged.

The following illustration shows a region created from basic geometry and converted to a region using the Region and Boundary commands. Using these commands you can take several complex shapes and join them into a single object. The point near the center represents the mass properties centroid for the region.

Objectives


■ Describe regions. ■ Access the Region command. ■ Use the Region command to create regions. ■ Describe the basic Boolean commands: Union, Subtract, and Intersect.

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About Regions

Regions are two-dimensional objects created from closed loops. They have similar behavior to 3D solids in that you can combine them in various ways with Boolean operations. The regions can also be used to create 3D solids. Multiple regions can also be combined into a single complex region for calculating areas.

The following illustration shows how you can combine three existing regions into a single, complex region to calculate area.

Definition of Regions

Regions are two-dimensional enclosed areas that have physical properties such as centroids. You create regions from objects that form closed loops. Loops can be combinations of lines, polylines, circles, arcs, ellipses, elliptical arcs, and splines. The objects that make up the loops must either be closed or form closed areas by sharing endpoints with other objects. Regions can be created using the Region and Boundary commands.

Using Regions Versus Boundaries

When you use the Region command to convert objects to a region, the new regions are placed on the current layer and the original objects are deleted. When you use the Boundary command to create regions, the new regions are also created on the current layer, but the original objects remain unchanged.

Examples of Regions

The following illustrations show the conversion of objects into regions.

Six individual objects, two circles and four closed loop shapes to be converted to regions.

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Six regions created, two circles and four closed loop shaped objects. The selected object shows an example of a region created.

A single circular shaped region created as a result of subtracting the four closed loop shaped regions from the inner circular region.

Guidelines for Creating Regions

Follow these guidelines to effectively create regions.

■ You can create regions out of multiple loops and out of open curves whose endpoints are connected and form loops.

■ You cannot form regions from open objects that intersect to form a closed area: for example, intersecting arcs or self-intersecting curves.

■ Composite regions can be created by combining, subtracting, or finding the intersection of regions.

■ REGION deletes the original objects after converting them to regions unless the system variable DELOBJ is set to 0.

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About Boolean Commands

The 3D Make control panel on the dashboard contains commands primarily used to create and edit 3D solid models. However, you can also use some of these commands when you work with 2D regions. Specifically, the Union, Subtract, and Intersect commands are invaluable when working with most 2D regions.

Also referred to as Boolean commands, the Union command joins separate 2D regions into a single region, the Subtract command subtracts regions from one another resulting in a single region, and the Intersect command creates a single region out of the common area of two or more regions.

Definition of Boolean Commands

Boolean commands are used to combine multiple parts into one, or remove sections from a solid or a region. These boolean commands are meant for creating composite solids or regions from two or more individual solids or regions.

Command Access

Boolean Commands are Editing Commands which are used for editing regions.

Union Command

The Union command combines two or more regions into a single region object.

Command Access

Boolean Commands

Toolbar: Solids Editing

Union

Command Line: UNION

Dashboard:

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Subtract Command

The Subtract command subtracts the area of one or more regions from one or more regions. It results in a single region object.

Command Access

Intersect Command

The Intersect command creates a single region object by comparing two or more regions and keeping only the area that is common to all regions selected.

Command Access

Subtract

Command Line: SUBTRACT

Dashboard:

Intersect

Command Line: INTERSECT

Dashboard:

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The following illustration shows how multiple regions on the left have been combined into a single region using the Union and Subtract commands.

Creating Regions

Regions are two-dimensional areas you create from closed shapes or loops. The Region command converts an object that encloses an area into a region object.

Region Command

When you start the Region command, you are prompted to select objects. Select objects that form a closed profile or loop. You can select circles, polylines, splines, and even regular lines and arcs as long as they are connected at the endpoints to other geometry to form a closed profile.

After you create the regions, you can combine them with other regions to form a single region object. You can also use the Region/Mass Properties command to view properties that are specific to region objects, as well as general properties, such as Area and Perimeter.

The following illustration shows how the outer region was combined with four circular regions to create a single outer region. The circles are automatically trimmed when the region is created.

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Command Access

Region

Command Line: REGION

Menu: Draw > Region

Toolbar: Draw

Dashboard:

Since the Region command requires the endpoints of the bounding geometry to match exactly, it will sometimes be more efficient to use the Boundary command and select Region as the object type. This can be more efficient since the Boundary command only requires the pick point be bounded by geometry on all sides. That bounding geometry does not have to have its endpoints match up perfectly, instead it can just intersect.

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Procedure: Creating Regions

The following steps show how to create regions.

1. Start the Region command.

2. Select objects in the drawing that form a closed profile.

NOTE: Verify that each closed profile or closed object is converted to individual regions and placed on the current layer.

3. After you create multiple regions, you can use the Boolean commands Union, Subtract, and Intersect to combine separate regions into a single region, subtract one region from another to create a new region, and create a region from the intersection of two or more regions.

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Exercise: Create Regions

In this exercise, you use the Region and Boundary commands to create regions in the drawing. You then use the Union and Subtract solids editing commands to combine the separate regions into a single region representing a specialty extrusion profile. Next, you use the Region/Mass Properties command to view the mass properties of the profile. You complete the exercise by creating a point object at the centroid of the region and comparing the point object’s position to the construction geometry representing the original center of the profile.

Scenario

You you want to create objects in the drawing which represent solids. You use the Region command along with solid editing boolean commands to combine those regions to get the desired shape.


Completing the ExerciseTo complete the exercise, follow the steps in this book or in the onscreen exercise. In the onscreen list of chapters and exercises, click Chapter 1: Drawing Objects. Click Exercise: Create Regions.

1. Open c_create_regions.dwg

2. On the dashboard, 2D Draw control panel:

■ Click Region.■ Click two points to window select the

extrusion objects.

■ Press ENTER.

■ The objects that qualify are converted to regions and placed on the current layer.

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3. To add the 3D Make control panel to the dashboard, right-click any icon on the dashboard, and in the shortcut menu select Control panels and click 3D Make to activate it. This will make boolean command icons available.

4. On the 3D Make control panel:

■ Click Union.■ Select the outer region and the four

circle regions.■ Press ENTER.

5. Verify that the circular regions are trimmed and combined with the outer region to create a single region.

6. On the Layers control panel, freeze the Construction layer.

7. Click Draw menu > Boundary.

■ In the Boundary Creation dialog box, select Region in the Object Type list.

8. Click Pick Points. In the drawing, select points inside the inner extrusion shapes as shown. Press ENTER.

9. On the Layers control panel, freeze the Visible layer.

10. On the 3D Make control panel:

■ Click Subtract.■ Select the outer region (1).■ Press ENTER.■ Select the inner region (2).■ Press ENTER.

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11. Touch any part of the outer profile to highlight the region. Notice how both outer and inner profiles are now a single region.

12. On the 3D Make control panel, click Union.

■ Select all regions.■ Press ENTER.

13. Touch any part of the profile with the cursor. Notice all geometry is highlighted, indicating a single region.

14. On the command line:

■ Enter SHADE.■ Press ENTER. The region is shaded in the

color of the layer on which it resides.

15. On the Standard toolbar, click Undo to return to wireframe display mode.

16. On the Layers control panel, thaw the Construction layer.

17. If the Inquiry toolbar is not open, right-click any toolbar and select Inquiry.

18. On the Inquiry toolbar, click Region/Mass Properties.

Select the region and press ENTER. The AutoCAD Text window appears, displaying the region’s mass properties.

19. Enter No for writing the analysis to a file. Press ENTER to close the text window.

20. Press F2 to reopen the text window.

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Chapter Summary

Chapter Summary AutoCAD contains useful tools for creating more complex drawing objects, as well as objects which can be used during the process of markup and revision.

Having completed this chapter, you can:

■ Create and edit multiline styles and multiline objects. ■ Create revision clouds. ■ Create wipeout objects in a drawing. ■ Create boundaries by using the Boundary command. ■ Create regions in a drawing using the Region and Boundary commands.


■ Enter POINT.■ Press ENTER.■ Note the Centroid X and Y values.■ Enter 107.7489, 72.1047. Press ENTER.■ Press F2 to close the text window. Note

the location of the point, slightly offset from the original construction lines. While the construction lines represent the center of the profile as it was drawn, the point represents the center of mass for the region.


■ Enter SHADE.■ Press ENTER.


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