Part I: CAD and AutoCAD for the Theater

Chapter Ten: Editing Drawing Objects


    1. Basic Editing Commands
      1. copy
      2. move
      3. erase
      4. rotate
      5. mirror
      6. cut, copy and paste
      7. divide
      8. measure
      9. AutoCAD Reference: Default Command Line Shortcuts
      10. trim, extend
    2. More Editing Commands
      1. explode
      2. array
      3. offset
      4. stretch
      5. scale
      6. fillet, champher
      7. break
    3. Special Editing
      1. properties
      2. grips
      3. pedit
      4. hatchedit
      5. ddedit
      6. spell
      7. attedit
      8. dimstyle
    4. New Selection Possibilities
      1. window
      2. crossing window
      3. previous, last
      4. add, remove
      5. filters

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Basic Editing Commands:

Become familiar with the basic commands for editing drawing elements: COPY, MOVE, ERASE, ROTATE and MIRROR. These are fairly self-explanatory. 'Copy' copies objects. [Move] moves objects. [Erase] erases drawing objects. If you mess up, don't forget [Undo] and [Redo].

By default [Rotate] rotates an object or set of objects in a counter-clockwise direction when using a positive number. Objects rotate in a clockwise direction if you provide a negative number. This default is changed with the [Units] command. If you mirror an object or group of objects with text or attributes and the text comes out backwards when you don't want it to, turn off <0> the MIRRTEXT system variable and try again.

The classic Windows CUT, COPY and PASTE commands are also available as [Alt+X], [Alt+C] and [Alt+V]. This is a very quick way to copy or move drawing objects from one drawing to another. The Edit pull-down menu includes special Copy and Paste options as well.

MEASURE and DIVIDE place Points (Nodes) or Blocks at divisions or measured intervals along a line, polyline, arc or circle. If the points do not show up after a DIVIDE command, they may be displaying as single points that disappear into the line. Change the point type with PDMODE or DDPTYPE. DDPTYPE displays a picture of each point type. You click on the one you want and click on OK. PDMODE will ask you for a point type number. If you know the number it is faster. If not, you will have to pull out the book to know what each numbered type looks like.

Learning to start commands quickly from the command line can be a real time saver. It is also the mark of an experienced drafter. AutoCAD provides one or two letter shortcuts to many commands. These are not written in stone. In fact, by editing the command alias list in the acad.pgp file found in AutoCAD "Support" directory, you can add, delete or create your own command aliases. The following list has some of the most common editing shortcuts.

AutoCAD Reference: Default Command Line Shortcuts

AR      ARRAY                ME      MEASURE
CH      PROPERTIES           MI      MIRROR
CO      COPY                 PE	     PEDIT
CP      COPY                 PROPS   PROPERTIES
D       DIMSTYLE             RO      ROTATE
E       ERASE                S       STRETCH
EX      EXTEND               SC      SCALE
F       FILLET               SP      SPELL
HE      HATCHEDIT            TR      TRIM
M       MOVE                 X       EXPLODE

TRIM allows you to select lines, 2d polylines, circles, and arcs and [Trim] or cut off other lines, 2d polylines, circles, and arcs at the first meeting with the first selection set. EXTEND is the logical opposite. Select lines, 2d polylines, circles, and arcs or a viewport and [Extend] lines, 2d polylines, and arcs to the nearest "boundry edge" or meeting with one of the first selection set, if there is one. Circles can't be Extended because they have no ends to extend. Trim and Extend work only in the same drawing plane.

chapter index.

More Editing Commands:

EXPLODE breaks complex objects down to simpler objects. A block will revert to its component objects, a polyline will become lines and arcs, and a polygon mesh will become 3D faces and lines.

ARRAY creates multiple copies of an object or group of objects in rows and columns (Rectangular Array), or in an arc or circle (Polar Array). This command is a huge time saver when creating even patterns. When an array of elements such as a frame is not uniform, it is often faster to create an Array and edit it than to start each element from scratch.

OFFSET constructs a new parallel line, polyline, arc or circle at a specified distance away from an existing line polyline, arc or circle. Select a circle to [Offset], type in [0.5"] for the offset distance, and select a point outside the circle. A new circle will appear with the same center point as the first, but with a 1" larger diameter (" outside of or offset from the original circle).

STRETCH pulls or stretches objects and groups of objects. When the [Stretch] command is activated, you select object endpoints and vertices with a Crossing Window selection, (see: "New Selecting Possibilities" below). All objects enclosed entirely within the Crossing Window are simply moved the distance and direction established by two pick points. For objects partially within the Crossing Window, only the end points and vertices within the Crossing Window are moved, causing the object geometry to stretch. Connections to objects not being moved are maintained. Stretch the end of a line and the line itself rubber-bands. The line is re-drawn between the endpoint's new location and the endpoint that was not moved or Stretched.

This command works excellent on lines, polylines, and arcs. Circles don't have endpoints or vertices to Stretch. A circle will move if it is entirely enclosed in the Crossing Window, otherwise it does nothing. Blocks and Xreferences do not Stretch, and only the insert point (and a portion of any of its objects) need be inside of the Crossing Window for the Block or Xref to be moved. Raster images stretch but maintain their X,Y proportions.

Complex objects such as Blocks, Xreferences and Raster images, have a Scale property relative to their original size. The SCALE command is different. [Scale] increases or decreases the size of an object or selection set of objects from a selected base point and according to a scale factor. The scale factor can be referenced to two set of points picked from the drawing geometry. AutoCAD figures out the Scale Factor between the two distance measurements it calculates.

Neatly bring two lines together with the FILLET command. [Fillet] extends or trims two line or arc objects until they meet each other. For Fillet to add a rounded corner at the meeting point of the lines and arcs, set the Fillet Radius to a non-zero length from the Fillet command line dialog. Once set, the Fillet command will continue to round all corners to the set radius until the Fillet Radius is reset to [0].

With a non-zero Radius set, Fillet will round a corner of a polyline by selecting both sides of the corner. To round the entire polyline, select the [P] or Polyline option from the Fillet command line dialog and select the polyline.

Similar to fillet, the CHAMFER command brings two lines or arcs together, but adds a "Chamfered" corner. This line across the corner is determined by choosing a Distance back from each side of the theoretical meeting point of the selected lines or by choosing an Angle from the first selected line and a distance back from the corner to start the angle.

Similar to the Fillet, Chamfer will chamfer all corners in a polyline with the Polyline option. When Chamfering a full polyline, it is better to Chamfer using equal chamfer distances. Non-uniform chamfer distances usually select in a counter-clockwise fashion, but the actual results are not easy to predict.

To remove a section from an arc, circle, line or polyline use the BREAK command. A section is removed from the object selection point (or a new First point) to a second pick point. Circles are changed to arcs by removing a section moving counter-clockwise from the first pick to the second pick point. Closed polylines break away from the first polyline vertex, or in the direction of the vertex numbering if the First point is the first vertex.

chapter index.

Special Editing:

We looked at the PROPERTIES command and the Properties Window fairly thoroughly in the last chapter. It not only informs us of current property values, but allows sophisticated properties editing.

By now, you have noticed that when selecting objects little boxes (default color blue) appear over various geometry points on the objects. These are called GRIPS. Grips can be turned Off <0> or On <1> with the [Grips] command. If you click on a grip box, it turns solid (red by default). What it does for you depends on the object and the geometry point selected. Grips on polyline vertices allow the vertices to be stretched. Grips at the quadrants of a circle pull the circle larger or smaller. Whereas the center grip in a circle will move the center point, and thus the circle.

Grips provide a very quick way to edit. With a grip active, a Right mouse click brings up a menu of additional possibilities. Shift + Right mouse click to bring up the OSnap menu.

Clicking on grips with the Shift key depressed allows you to make several grips active at once. You will then need to click on a grip without the shift key depressed to begin the group grip edit. At this point, each grip acts as if it were being individually edited, but according to the one set of choices.

Polyline Edit or PEDIT provides a special menu of editing possibilities for 2d or 3d polylines and 3d polygon meshes. This command allows you to Close an open polyline, Join lines and polylines to the selected polyline, change line Width (only one width for the entire line), form the polyline into a curve to Fit the vertices, turn the polyline into a Spline around the vertices, Decurve a Splined or Fit polyline, and change the Ltype gen property for the polyline.

When editing 3d Polylines, the available editing choices are fewer. Editing 3d Polygon Meshes with 'Pedit' gives several choices appropriate to a 3d mesh. We'll have to cover that in the 3d section.

The main text editor DDEDIT command brings up an Edit Text window for single line text and a Multiline Text Editor with comprehensive editing capabilities for MText. It is possible to change the text editor to a simple ASCII word processor such as Notepad or Write, but this slows the editing process down and I can't recommend it. The change is made in the Files/Text Editor Application section of the Options menu. To reset to the default AutoCAD editor, type [Internal] in the program file line.

The SPELL command checks the spelling of Text, MText and Attributes. It will not check spelling of Text or MText inside of a block, but will check the Attribute values. Foriegn language dictionaries are a available in the Options menu, Dictionaries section. American, French and English are offered by default, I am sure that others are available from Autodesk or third party suppliers.

Attributes that have not yet been blocked can be edited with ddedit. Editing the attribute values of an block within the drawing can be done with the ATTEDIT command.

Two important object classes which we haven't covered yet are HATCH and DIMENSIONS. They both have their own special editing windows: HATCHEDIT and DIMSTYLE respectively. We will cover the editors when we cover the objects.

Other editing menu options include the Drawing Order or DRAWORDER command, the MultiLine editor MLEDIT command, and the Spline editor command SPLINEDIT.

chapter index.

New Selection Possibilities:

Notice that when you click on a blank spot on the screen and drag the mouse a box appears. If you drag up or down to the right, a solid line box is pulled out. This is a Selection Set Window. Click again and all objects completely enclosed by the window are Selected. This works as a selection for subsequent commands or as a selection in responce to a command prompt to select objects.

Dragging a window up or down to the left and clicking produces a window with a dashed line border. This is a Crossing Window. All objects enclosed or touched (crossed) by the window are selected.

Responding to a selection prompt with Previous or[P] reactivates the previous selection set. Last or [L] selectes the last object created.

To remove objects from a selection set, without canceling the selection and starting over, type [R] for Remove and hit Enter. Picking selected objects removes them from the current selection set. To continue adding to the selection set, type [A] for Add and the selection process returns to the default mode of adding selected objects to the selection set.

The FILTER command opens the Object Selection Filters window. This window allows selection of drawing objects by choosing properties and object types. Logical operators allow complex filtering of objects, as in "all circles on layer x or y with greater than a 1" radius and less than a 12" radius." The [Filter] command also allows a set of selection filters to be saved for reuse.

A short version of the Filter command is also available. The QSELECT command is available through a button on the upper right corner of the Object Properties window.

chapter index.

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Copyright © 1999 Wm W Wells. All rights reserved.