A spline is a special type of nonuniform curved line. The SPLINE command is. Drawing Multilines

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1 Splines Learning Objectives After completing this chapter, you will be able todo thefollowing: / Use the MLINE command to draw multilines. / Create your own multiline styles with the MLSTYLE command. / Edit multiline intersections, corners, and vertices. / Draw and edit spline curves. This chapter explores drawing and editing AutoCAD multilines and splines. Multilines are combinations of parallel lines consisting of up to 16 individual lines called elements. You can offset the elements as needed to create a pattern for any field of drafting, such as architectural, schematic, or mechanical. Multilines are drawn using the MLINE command and its options and are modified using the MLEDIT command. A spline is a special type of nonuniform curved line. The SPLINE command is used to create true splines. Splines can be edited using the SPLINEDIT command. multiline: A single object consisting of up to 16 parallel line elements. elements: The individual lines that make up a multiline. spline: A special type of nonuniform curved line. C Drawing Multilines j> The MLINE command is used to draw multilines. To access the MLINE command, pick Draw > Multiline or type ML or MLINE. The prompts and options for the MLINE command are similar to those for the LINE command. You can use the Close option at the last prompt to close a polygon. Enter Uduring the command sequence to undo the previously drawn multiline segment. A multiline configuration, or style, can be set using the MLSTYLE command. The default AutoCAD multiline style has two elements and is called STANDARD and consists of two parallel lines. If you pick on one line to display grips, you can see that the entered coordinates correspond to both lines. Multiline styles are described later in this chapter. Multiline Justification Multiline justification determines how the line elements are offset from the defi nition points provided. Definition points are the points you pick or coordinates you enter when drawing multilines. The justification is based on counterclockwise move ment and can be specified only once during a single MLINE command sequence. The Justification options are Top (default), Zero, and Bottom. definition points: The points you pick or coordinates you enter to specify multilines. 497

2 To change the justification, type J at the first prompt displayed after entering the MLINE command. Enter the first letter of the desired justification format (T, Z, or B). The results of the three different Justification options using identical point entries are shown in Figure Observe each orientation as you go through the following command sequence: Command: ML or MLINEJ Current settings: Justification = current, Scale = current, Style = current Specify start point or [Justification/Scale/STyle]: J J Enter justification type [Top/Zero/Bottom] <current>: (type T, Z, or B, and press [Enter]) Current settings: Justification = specified value, Scale = current, Style = current Specify start point or [Justification/Scale/STyle]: 2,2J Specify next point: 6,2J Specify next point or [Undo]: 6,6J Specify next point or [Close/Undo]: 2,6J Specify next point or [Close/Undo]: CJ Command: The current multiline justification setting is stored in the CMLJUST system variable. You can change the setting by entering 0 for the Top option, 1 for the Zero option, or 2 for the Bottom option. As shown in Figure 15-1, the multiline Justification options control the direction of the offsets for elements of the current style. The multi line segments in these examples are drawn in a counterclockwise direction. Unexpected results can sometimes occur when you use the MLINE command, depending on the justification and drawing direction. j Exercise 15-1 Complete the exercise on the Student CD. Adjusting the Multiline Scale The Scale option of the MLINE command is a multiplier applied to the offset distance specified in the multiline style. The multiplier is stored in the CMLSCALE system variable. The example in the previous section used a default scale setting of 1. With this setting, the distance between multiline elements is equal to 1 times the Figure Multilines drawn using each of the three justification options. The definition points (represented by plus symbols) are picked in a counterclockwise rotation. Top Justification Zero Justification Bottom Justification 498 AutoCAD and Its Applications Basics

3 offset distance. For example, if the offset distance is.5, the distance between multiline elements is.5 when the multiline scale is 1. If the multiline scale is specified as 2, however, the distance between multiline elements is 1 (.5 x 2). Multilines drawn with different scale settings are shown in Figure C Exercise 15-2 Complete the exercise on the Student CD. Creating Multiline Styles Multiline styles are defined using the Multiline Style dialog box. The current style is stored in the CMLSTYLE system variable. The Multiline Style dialogbox can be accessed by picking Format > Multiline Style... from the pull-down menu or by typing MLSTYLE. The Multiline Style dialog box allows you to define, edit, and save multiline styles. See Figure You can save styles to an external file so they can be used in other drawings. The Preview of: area in the lower part of the Multiline Style dialog box displays a representation of the selected multiline style. Figure Multiline scale settings. Scale =.25 Scale =.5 Scale = 1 Scale = 2 Figure The Multiline Style dialog box is used to define, edit, and save multiline styles. List of available styles Description of selected style Preview of selected style IMultiline Style CurrentMultiline Style:STANDARD Styles: 'mmni STANDARD Description: Pieview of: R0AD1 Set Current New.. 3f Modify.. Zf Delete Load.. Save. i ^ Sets the selected style current Creates a new style Modifies the 'selected style Renames the selected style. Deletes the selected style \ Allows you to import a style from an external file Help \ Saves the selected style to an external file Chapter 15 Multilines and Splines 499

4 Icaps: Short lines connecting the start points and endpoints of multiline elements. Picking the New... button in the Multiline Style dialog box displays the Create New Multiline Style dialog box shown in Figure 15-4.In the New Style Name: text box, enter a name for the new multiline style. The properties from an existing style can be used for the new style by selecting it from the Start With: drop-down list. After a name has been entered, the Continue button becomes active. Picking this button opens the New Multiline Style dialog box. The options in this dialog box define the appearance of the multiline. See Figure 15-5.The Description: field is optional, but it can be used to enter a brief description of the multiline style. Using the caps, fill, and joints settings The settings in the Caps area control the placement of caps on multilines. Caps are lines connecting the corresponding vertices of the start points or endpoints of the multiline elements. Using the check boxes, you can set caps at the start points, endpoints, or both. Several examples of differentcap options are shown in Figure Figure Tocreate a new multiline style, specify a name and existing multiline style settings in the Create New Multiline Style dialog box. ICreate New Multiline Style New Style Name: Type in a name for the new style Stait With R0AD1 Cancel Help Select an existing \style to use its properties for the new style Figure The options in the New Multiline Style dialog box control all the settings for a multiline. Description of the style SJNew Multiline Style: WALLS Caps area controls multiline"" capping Determines the fill setting for the multiline"" style Description: Caps Start End Line: Outer arc: Inner arcs: Angle: Fill color: 'fj None V Offset Color Linetype 10.5 BYLAYER ByLayer BYLAYER ByLayer Offset: Color: Add,0.500 Delete ByLayer v Elements area sets the lines and their properties Option for displaying joints.display joints: fj Linetype: Linetype.. Help Figure Various cap options used with multilines. Caps Off Line Caps On Outer Arcs On Inner Arcs On 90 Angle Caps Off 45 Angle Caps Off 45 Angle Line Caps On 500 AutoCAD and Its Applications Basics

5 The caps can be drawn as straight lines or arcs.arcscan be set to connect the ends of the outermost elements only,pairs of innerelements, or both the outer and innerelements. The multiline style must contain at least two multiline elements for outer arcs to be drawn. Arcs are drawn tangent to the elements they connect. You can also change the angle of the caps relative to the direction of the multiline elements.todo this, enter values in the Angle: text boxes. There is a text box for the start points and another for the endpoints. The Fill color: setting in the Fill area allows you to create a solid multiline. When the Fill color: setting is set to None, there is no fill. To specify the fill color, select a color from the Fill color: drop-down list. Multilines drawn with and without fills are shown in Figure When Display joints: is checked, joints are displayed on the multiline. Joints are lines connecting the vertices of adjacent multiline elements. They are also referred to as miters. Multilines drawn with and without joints are shown in Figure Setting the element properties The Elements area allows you to add or delete more elements (lines) from the multiline style and specify the properties of each element. The options in this area change properties including linetype, color, and offset. After you have set the proper ties, pick OK to apply them to the new multiline style. The new style is then added to the Multiline Style dialog box. joints (miters): Lines connecting the vertices of adjacent multiline elements. Changing the Multiline Style You can specify the current multiline style by using the STyle option of the MLINE command. To use a saved multiline style, enter ST to access the STyle option, and then enter the style name. Before you can access a new multiline style, however, you must create and save it using the Multiline Style dialog box. If you forget the name of the desired multiline style, you can enter? at the Enter mline style name or [?]: prompt. The text window opens, listing the currently loaded multiline styles. See Figure Type the name of the style you want to use. If you try to specify a multiline style that is not loaded, the Load multiline style from file dialog box is displayed. You can look for the desired multiline style in the acad.min file library, or you can pick the Tools button and then Find... to open the Find: dialog box. C Exercise 15-3 Complete the exercise on the Student CD. Figure The multiline Fill color: setting allows you to draw multilines with a solid fill pattern. FillSetting On FillSetting Off Figure Multilines can be drawn with or without displayed joints. Joints Enabled Joints Disabled Chapter 15 Multilines and Splines 501

6 Figure A list of loaded multiline styles can be displayed in the text window. n Edit AutoCAD Text Window Drawing5.dwg Command: HLINE HL Current settings: Justification = Top, Scale , Style = P.OAD1 Specify start point or [Justification/Scale/STyle]: ST Enter mline style name or [?]:? Loaded mline styles: Name Description R0AD1 TU0-LANE ROAD UITH CENTERLINE STANDARD Enter mline style name or [?]: c Editing Multilines The MLEDIT command permits limited editing operations for multiline objects. Todisplay the Multilines Edit Tools dialog box, pick Modify > Object > Multiline... from the pull-down menu or type MLEDIT. See Figure This dialog box contains four columns. Each column contains three buttons of related command options. The image on each button gives you an example of what to expect when using the editing option. Whenyou pick a button, the dialog boxclosesand AutoCAD prompts you to continue with the command. The command options are described in the following sections. ) background: The first multiline you select to create a closed cross intersection. foreground: The second multiline you select to create a closed cross intersection. Editing Intersections The first (left) column in the Multilines Edit Tools dialog box displays three different types of multiline intersections. Picking a button allows you to create the type of intersection shown. The effects of the buttons in the first column are shown in Figure and described below. Closed Cross. When you use this option, the first multiline you select is called the background, and the second multiline is called the foreground. A closed cross intersection is created by trimming the background, while the foreground remains unchanged. The trimming is apparent, not actual. The line visibility of the background multiline is changed, but it is still a single multiline. Figure The Multilines Edit Tools dialog box has twelve different options for editing multilines. Cross _ options 'Multilines Edit Tools To use a tool, click on the icon. Objecl selection must be performed after the tool has been selected MO r,.,-.ecttec:: Closed Doss JZJ Open Cross bid Merged Cross Closed Tee ~\r Open Tee np Merged Tee Coiner Joint Delete Vertex Cutting and welding options Corner joint and vertex options 502 AutoCAD and Its Applications Basics

7 Figure Creating closed cross, open cross, and merged cross intersections with the MLEDIT command. [Original Crossing Multilines First pick^^[ ] / Second pick Closed Cross Open Cross Merged Cross + J Open Cross. Select the Open Cross button to trim all the elements of the first multiline and only the outer elements of the second multiline. The command sequence is the same as that used for the Closed Cross option. Merged Cross. The Merged Cross button allows you to trim the outer elements of both multilines. The inner elements are not changed. Exercise 15-4 Complete the exercise on the Student CD. Editing Tees The buttons in the second column of the Multilines Edit Tools dialog box are used to edit multiline tees. The results of using the tee options are illustrated in Figure The three options are: Closed Tee. Trims or extends the first selected multiline to its intersection with the second multiline. Open Tee. Trims the elements where a trimmed or extended multiline intersects with another multiline. The first pick specifies the multiline to trim or extend, and the second pick specifies the intersecting multiline. The intersecting multi line is trimmed and left open where the two multilines join. Merged Tee. Trims the intersectingmultilineafter the first multiline is trimmed or extended. The inner elements, however, are joined. This creates an open appearance with the outer elements, while merging the inner elements. Figure Using the tee options of the MLEDIT command to edit multiline tees. [ Original Multilines First pick rh>^ or Closed Tee Open Tee Merged Tee JIL \^_ Second pick J Chapter 15 Multilines and Splines 503

8 Exercise 15-5 Complete the exercise on the Student CD. Editing Corner Joints and Multiline Vertices The buttons in the third column of the Multilines Edit Tools dialog box provide options for creating corner joints and editing multiline vertices. The three options are: Corner Joint. Creates a corner joint between two multilines. The first multiline is trimmed or extended to its intersection with the second multiline, as shown in Figure Add Vertex. Adds a vertex to an existing multiline at the location you pick. See Figure The command sequence differs slightly from the sequences used with the other MLEDIT options. After you select the Add Vertex option, AutoCAD prompts you to pick a location for the vertex. Delete Vertex. Removes a vertex from an existing multiline. The vertex closest to the location you pick is deleted. See Figure The command sequence is the same as for the Add Vertex option. Exercise 15-6 Complete the exercise on the Student CD. Figure A corner joint can be created between two multilines using the Corner Joint option of the MLEDIT command. Pick the second multiline Pick the first multiline Crossing Multilines Multilines after Using the Corner Joint Option Figure The Add Vertexand Delete Vertex options of the MLEDIT command are used to edit multiline vertices. Vertex is added Vertex closest to pick at picklocation location is deleted Multiline before Vertex Is Added Multiline after Vertex Is Added Multiline before Vertex Is Deleted Multiline after Vertex Is Deleted 504 AutoCAD and Its Applications Basics

9 Figure The MLEDIT cutting options allow you to cut single multiline elements or entire multilines between two specified points. f Original Multiline Cut Single Cut All ^\ Pick points Q E3 V ) Cutting and Welding Multilines The fourth column of buttons in the Multilines Edit Tools dialog box is used for cutting a portion out of a single multiline element or the entire multiline. The spaces between multiline elements can also be connected. AutoCAD refers to the connecting operation as welding. The MLEDIT cutting and welding options are: Cut Single. Cuts a single multiline element between two specified points, as shown in Figure Cutting affects only the visibility of elements and does not separate a multiline object. The multiline is still a single object. After you select the Cut Single option, AutoCAD prompts you to pick the cutting points. Cut All. Cutsallelements ofa multiline between specified points. See Figure The multiline is still a single object,even though it appears to be separated. Weld All. Repairs all cuts in a multiline. Select the Weld All button and select a point on each side of the cut multiline. The multiline is restored to its precut condition. cutting: The process deleting a portion of a multiline element or an entire multiline. welding: The process of connecting the spaces between multiline elements. c Multiline objects can be converted to individual line segments with the EXPLODE command. This command is explained in Chapters 14 and 23. Exercise 15-7 Complete the exercise on the Student CD. c Drawing Splines The SPLINE command is used to create a special type of curve called a nonuniform rational B-spline (NURBS) curve. A NURBS curve is considered to be a true spline. A spline created by fitting a spline curve to a polylineis merely a linear approximation of a true spline and is not as accurate. An additional advantage of spline objects over smoothed polylines is that splines use less disk space. Toaccess the SPLINE command, pick the Spline button on the 2D Draw control panel of the Dashboard or the Draw toolbar, pick Draw >Spline, or type SPL or SPLINE. A spline is created by specifying the control points using any standard coordinate entry method. nonuniform rational B-spline (NURBS) curve: A true (mathematically correct) spline. limi SPLINE SPL 2D Draw > Spline H Draw Spline LU Z _1 Q. CO Draw > Spline Chapter 15 Multilines and Splines 505

10 Command: SPL or SPLINEJ Specify first point or [Object]: 2,2J Specify next point: 4,4J Specify next point or [Close/Fit tolerance] <start tangent>: 6,2J Specify next point or [Close/Fit tolerance] <start tangentx J Specify start tangent: J Specify end tangent: J Command: After you have specified all the necessary points along the spline, press [Enter] to end the point specification process and to allow the start tangency and end tangency to be entered. Specifying the tangents changes the direction in which the spline curve begins and ends. Pressing [Enter] at these prompts accepts the default direction, as calculated by AutoCAD, for the specified curve. The results of the previous command sequence are shown in Figure If you specify only two points for a spline curve and accept Auto CAD's default start and end tangents, an object that looks like a line is created, but the object is a spline. Drawing Closed Splines The Close option of the SPLINE command enables you to draw closed splines. See Figure After closing a spline, you are prompted to specify a tangent direction for the start point or endpoint of the spline. Pressing [Enter] accepts the default calcu lated by AutoCAD. Figure A spline drawn with the SPLINE command. AutoCAD's default start and end tangents were used for this spline. Figure Using the Close option of the SPLINE command with AutoCAD default tangents to draw a closed spline. Compare this spline to the object shown in Figure AutoCAD and Its Applications Basics

11 Altering the Fit Tolerance Specifications When drawing splines, you can achieve different results by altering the speci fications used with the Fit tolerance option. The outcomes of different settings vary depending on the configuration of the individual spline object. The setting specifies a tolerance within which the spline curve falls as it passes through the control points. Specifying the Start and End Tangents The previous SPLINE command examples used AutoCAD's default start and end tangents. You can set start and end tangent directions by entering values at the prompts that appear after you pick the points of the spline. The tangency is based on the tangent direction of the selected point. The results of using the horizontal and vertical tangent directions using Ortho mode are shown in Figure Converting a Spline-Fitted Polyline to a Spline A spline-fitted polyline objectcan be converted to a spline object using the Object option of the SPLINE command. This option works for both 2Dand 3D polylines. Exercise 15-8 Complete the exercise on the Student CD. Figure These splines were drawn through the same points, but they have different start and end tangent directions. The arrows indicate the tangent directions. Vertical Tangents Horizontal Tangents C Editing Splines The SPLINEDIT command allows you to edit spline objects. Severalediting options are available. You canadd, move, or deletecontrol pointstoalter the shape ofan existing curve. You can also open or close a spline and change the start and end tangents. To access the SPLINEDIT command, pick the Edit Spline button on the Modify II toolbar, pick Modify >Object > Spline, or type SPEor SPLINEDIT. You are prompted to select the spline to be edited. When you pick a spline, the control points are identified 3 fit points: Spline control points. by grips, as shown in Figure You must then select one of the six SPLINEDIT EBB options. These are described in the following sections. Editing Fit Data The Fit data option of the SPLINEDIT command allows spline control points to be edited. Spline control points are called fit points. The Fit data option has several suboptions: Modify > Object > Spline Open Move vertex Refine reverse Undo Chapter 15 Multilines and Splines 507

12 Figure The control points for a spline are displayed as grips. Command: SPE or SPLINEDITJ Select spline: (pick a spline) Enter an option [Fit data/close/move vertex/refine/reverse/undo]: FJ Enter a fit data option [Add/Close/Delete/Move/Purge/Tangents/toLerance/eXit] <exit>: Each of the Fit data suboptions is explained next. See Figure for examples of using these options. Add. This suboption adds new fit points to a spline definition. A new fit point can be located by picking a point or entering coordinates. Fit points appear as unselected grips. When a fitpoint is selected, it becomes highlighted along with the next fit point on the spline. You can then add a fit point between the two highlighted points. If the endpoint of the spline is selected, only the endpoint Figure Examples of using the Fit data options of the SPLINEDIT command to edit a spline. Compare the original spline to each of the edited objects. Original Spline Adding a Fit Point Original location New location Deleted point Moving a Fit Point D- Deleting a Fit Point -D Using the Close Option Start and end tangents Editing the Tangents 508 AutoCAD and Its Applications Basics

13 becomes highlighted. If the start point of the spline is selected, you are asked whether you want the new fit point inserted before or after the existing one. Respond by entering Aor Baccordingly. When a fit point is added, the spline curve is refit through the added point. TheAdd suboption functions in a runningmode. Thismeansyoucancontinue to add points as needed. By pressing [Enter] at a Specify new point <exit>: prompt, youcanselect otherexisting fit pointstoadd pointsanywhere on the spline. Close/Open. If the selected spline is open, the Close suboption is displayed. If the spline is closed, the Open suboption is displayed. These options allow you to open a closed spline or close an open spline. Delete. The Delete suboption deletes fit points as needed. At least two fit points, however, must remain. Like the Add suboption, the Delete suboption operates in a running mode, allowing as many deletions as needed. The spline is recurved through the remaining fit points. Move. This suboption allows fit points to be moved as necessary. When you enter the Move suboption, the start point of the spline is highlighted. You can specify a different location by picking a new point. You can also specify other fit points to move. The options are explained as follows: Specify new location. Allows you to move the currently highlighted point to a specified location. Next. Highlightsthe next fit point. This option is activated by pressing [Enter]. Previous. Highlights the previous fit point. Select point. Allows you to pick a different fit point to move. exit. Returns you to the Fit data option prompt. Purge. This suboption lets you remove fit point data from a spline. After using this option, the resulting spline is not as easy to edit. In very large drawings in which many complex splines have been created, such as Geographical Information Systems (GIS) drawings, purging fit point data reduces the file size by simplifying the spline definitions. After a spline is purged, the Fit data option is no longer displayed by the SPLINEDIT command for the purged spline. Tangents. This suboption allows you to edit the start and end tangents for an open spline and the start tangent for a closed spline. The tangency is based on the direction of the selected point. You can also use the System default option to set the tangency values to the AutoCAD defaults. tolerance. Fit tolerance values can be adjusted using this suboption. The results are immediate, so the fit tolerance can be adjusted as necessary to produce different results. exit. Entering this suboption returns you to the SPLINEDIT command option prompt. Opening or Closing a Spline The Open and Close options of the SPLINEDIT command are alternately displayed, depending on the current status of the spline objectbeing edited. If the spline is open, the Close option is displayed. The Open option is displayed if the spline is closed. Moving a Vertex The Move vertex option of the SPLINEDIT command allows you to move the fit points of a spline. When you access this option,you can specifya new location for a selected fit point. The options displayed are identical to those used with the Move suboption of the Fit data option.you can picka new location forthe highlighted fit point, or you can enter a suboption. The Move vertex suboptions are explained below: Specify new location. Moves the currently highlighted point to a specified location. Next. Highlights the next fit point. Chapter 15 Multilines and Splines 509

14 Previous. Highlights the previous fit point. Select point. Picks a different fit point to move, rather than cycling through points with the Next or Previous suboptions. exit. Returns to the SPLINEDIT prompt. Exercise 15-9 Completethe exercise on the Student CD. I order: In a spline, the degree of the spline polynomial + 1. Smoothing or Reshaping a Section of the Spline The Refine option of the SPLINEDIT command allows fine-tuning of the spline curve. Fitpoints canbe added to help smooth or reshape a section of the spline. When youuse this option, the fit pointdataisremoved from the spline. Thefollowing refining options are available: Add control point. Specifies new fit points on a spline as needed. Elevate order. Causes more control points to appear on the curve for greater control. The order ofa spline is the degree of the spline polynomial +1. In simple terms, it is the degree of refinement of the spline. For example, a cubic spline has an order of 4. In Figure 15-21, the order of the spline is elevated from 4 to 6. The order setting can be from 4 to 26, but it cannot be adjusted downward. For example, if the order is set to 24, the only remaining settings are 25 and 26. Weight. Changes the weight of a control point. When all control points have the same weight, they exert the same amount of pull on the spline. When a weight value is reduced for a control point, the spline is not pulled as close to the point as before. Likewise, when a weight value is increased, the control point exerts more pull on the spline. See Figure The default setting of can be adjusted to a higher or lower value. The weight setting must be positive. The control point selection suboptions of the Weight option are the same as those used with the Move vertex option of the SPLINEDIT command. You can specify a new weight for the highlighted control point using the Enter new weight option. Figure The effects of elevating the order of a spline and increasing the weight of an individual control point. Control point Original Spline Elevating the Order from 4 to 6 Increasing the weight of this control point to 6 pulls the spline away from the other control points Increasing the Weight of One Control Point 510 AutoCAD and Its Applications Basics

15 Reversing the Order of Spline Control Points The reverse option of the SPLINEDIT command allows you to reverse the listed order ofthespline control points. This makes theprevious startpointthenewendpoint and the previous endpoint the new start point. Using this option affects the various control point selection options. Undoing Splinedit Changes The Undo option of the SPLINEDIT command undoes the previous change made to the spline. You can use this option to undo changes back to the beginning of the current SPLINEDIT command sequence. Exercise Complete the exercise on the Student CD. Chapter Test Answer the following questions. Write your answers on a separate sheet ofpaper orcomplete the electronic chapter test on the Student CD. 1. Give the command and entries needed to draw a multiline with zero justification and the saved style ROAD1. A. Command: B. Current settings: Justification = current, Scale = current, Style = current Specify start point or [Justification/Scale/STyle]: C. Enter mline style name or [?]: D. Current settings: Justification = current, Scale = current, Style = ROAD1 Specify start point or [Justification/Scale/STyle]: E. Enter justification type [Top/Zero/Bottom] <current>: F. Current settings: Justification = Zero, Scale = current, Style = ROAD1 Specify start point or [Justification/Scale/STyle]: G. Specify next point: H. Specify next point or [Undo]: 2. Name the MLINE command option that establishes how the resulting lines are offset based on the definition points provided. 3. Name the system variable that controls the multiplier value for the offset dis tances specified with the MLINE command. 4. How do you access the Multiline Style dialog box? 5. Define caps. 6. Define joints. 7. What is displayed when you enter the MLEDIT command? 8. How do you accessone of the MLEDIT options? 9. List the three options used for editing multiline intersections with the MLEDIT command. 10. Name the MLEDIT option in which the intersecting multiline is trimmed and left open after the first multiline is trimmed or extended to its intersection with the intersecting multiline. 11. Name the MLEDIT option that allows you to remove a vertex from an existing multiline. 12. Name the MLEDIT option that lets you remove a portion from an individual mul tiline element. Cliapter 15 Multilines and Splines 511

16 13. Name the MLEDIT option that removes all the elements of a multiline between two specified points. 14. Name the MLEDIT option that repairs all cutsin a multilinebetweentwo selected points. 15. Name the command thatcan be used to create a true spline. 16. How do you accept the AutoCAD defaults for the start and end tangents of a spline? 17. Name the SPLINE command option that allows you to turn a spline-fitted poly line into a true spline. 18. Name the command that allows you to edit splines. 19. What is the purpose ofthe Addsuboptionofthe Fit data option ofthe SPLINEDIT command? 20. What is the minimum number of fit points for a spline? 21. Name the SPLINEDIT option that allows you to movethe fit points in a spline. 22. What is the purpose of the Refine option of the SPLINEDIT command? 23. Identify the Refine suboption of the SPLINEDIT command that lets you increase, but not decrease, the number of control points appearing on a spline curve. 24. Name the Refine suboption of the SPLINEDIT command that controls the pull exerted by a control point on a spline. 25. How many operations can you undo inside the SPLINEDIT command with the Undo option? Drawing Problems Start a new drawing for each of the following problems. Specify your own units, limits, and other settings to suit each problem. 1. Draw the objects shown using the MLINE command. Use the justification options indicated with each illustration. Set the limits to 11,8.5; grid spacing to.50; snap spacing to.25; and the offset for themultiline elements to.125. Donot add textor dimensions. Save the drawing as P Zero Justification Bottom Justification Top Justification 512 AutoCAD and Its Applications Basics

17 2. Draw the partial floor plan using the multiline commands. Carefully observe how the dimensions correlate with the multiline elements to determine your jus tification settings. Also, use the appropriate cap and multiline editing options. Use architectural units. Set the limits to 88",68"; grid spacing to 24"; and snap spacing to 12". Make all walls 6" thick. Do not add dimensions. Save the drawing as P " 24-0" 24-0',^_L 3'-0" 4-0" 6'-0' 6'-0" 4'-0" 8'-0" 3' S'-6' 3. Draw the proposed subdivision map using the multiline commands. The roads are 30' wide. Use a centerline linetype for the center of each road. Adjust the linetype scale as needed. Do not include dimensions. Save the drawing as P15-3. Cliapter 15 Multilines and Splines 513

18 4. Draw the partial floor plan using multilines for the walls. Do not dimension the floor plan. Save the drawing as P Draw the proposed electrical circuit using the multiline commands. Establish a line offset proportional to the given layout. Use a phantom linetypefor the center of each run. Do not draw the grid, which is provided as a drawing aid. Save the drawing as P AutoCAD and Its Applications Basics

19 6. Use SPLINE and other commands, such as ELLIPSE, MIRROR, and OFFSET, to design an architectural door knocker similar to the one shown. Use an appropri ate text command and font to place your initials in the center. Save the drawing as P Use the SPLINE command to draw the curve for the cam displacement diagram below. Use the following guidelines and the given drawing to complete this problem: A. The total rise equals B. The total displacement can be any length. C. Divide the total displacement into 30 increments. D. Draw a half circle divided into 6 equal parts on one end. E. Draw a horizontal line from each division of the half circle to the other end of the diagram. F. Draw the displacement curve with the SPLINE command by picking points where the horizontal and vertical lines cross. G. Label the displacement increments along the horizontal scale as shown. Save the drawing as P15-7. T0TA. C ISF'LACEMENT - s J- RISE FALL 4/ \ M 2. DO *v \ 1^ X 0* 60' 120* 180' 240' 300" 360" 30" 90" 150* 210" 270' 330' Chapter 15 Multilines and Splines 515

20 n l Draw a spline similar to the original spline shown below. Copy the spline seven times to create a layout similar to the one given. Perform the SPLINEDIT opera tions identified under each of the seven copies. Save the drawing as P15-8. Original Spline Close Move a Control Point Elevate the Order to 10 Add Two Control Points Delete a Control Point Edit the Tangents Increase the Weight of a Control Point to AutoCAD and Its Applications Basics