Chapter 6: Fundamentals V
After completing this Chapter, you will be able to use the following
features:
•Multiline – Drawing and Modification
•Create and Modify Multiline styles
•Splines – Drawing and Modification
•Wipeout and Revcloud commands
•Advanced Modification tools
•Inquiry commands
•Changing System Variables
Multiline
The MLINE command allows to draw multiple parallel line
segments, similar to polyline segments that have been offset one
or more times. The properties of each element of a multiline are
determined by the style that is current when the multiline is
drawn.
Available options include:
Start point selection (default) specifies the starting point of
the multiline, known as its origin. Once the starting point is
specified for a multiline, AutoCAD prompts for subsequent
points until the command is exited.
Justification selection determines the relationship between the
elements of the multiline and the line specified by way of the
placement of the points. The suboptions available are: Top, Zero
and Bottom.
Scale selection determines the value used for offsetting
elements when drawing them relative to the values assigned.
Style selection sets the current multiline style from the available
styles.
Editing Multilines
The MLEDIT command modifies the intersections of two or more
multilines or cut gaps in the lines of a multiline. Difference tools
are available for the type of intersection operated on (cross, tee, or
vertex) and if one or more elements need to be cut or welded.
Multiline Edit toolbox
The first column in the Multiline Edit Tools image dialog box works
on multilines that cross, the second works on multilines that form a
tee, the third works on corner joints and vertices, and the fourth works
on multilines to be cut or welded.
Closed Cross selection cuts all lines that make up the second
multiline you select at the point where it crosses the first
multiline.
Open Cross selection cuts all lines that make up the first
multiline you select and cuts only the outside line of the second
multiline.
Merged Cross selection cuts all lines that make up the
intersecting multiline you select except the centerlines.
Closed Tee selection extends or shortens the first multiline you
identify to its intersection with the second multiline.
Open Tee selection is similar to the Closed Tee option, except
it leaves an open end at the intersecting multiline.
Merged Tee selection is similar to the Open Tee option,
except the centerline of the first multiline is extended to the
center of the intersecting multiline.
Corner Joint selection lengthens or shortens each of the two
multilines you select as necessary to create a clean intersection.
Add Vertex selection adds a vertex to a multiline.
Delete Vertex selection deletes a vertex from a multiline.
Cut Single selection cuts a selected element of a multiline
between two cut points.
Cut All selection removes a portion of the multiline you
select between two cut points.
Weld All selection rejoins multiline segments that have been
cut.
Create and Modify Multiline Styles
The MLSTYLE command is used to create a new Multiline Style or
edit an existing one. You can define a multiline style comprised of up
to 16 lines, called elements. The style controls the number of
elements and the properties of each element. In addition you can
specify the background color and the end caps of each multiline.
Multiline Styles Dialog box
New Multiline Style dialog box
Splines
The SPLINE command is used to draw a curve through or near
points in a series. The type of curve is a nonuniform rational B-spline
(NURBS ). This type is used for drawing curves with irregularly
varying radii, such as topographical contour lines.
Editing Splines
Splines created by means of the SPLINE command have numerous
characteristics that can be changed with the SPLINEDIT command.
These include quantity and location of fit points, end characteristics
such as open/close and tangencies, and tolerance of the spline (how
near the spline is drawn to fit points).
Wipeout
The WIPEOUT command allows to create an area on the screen
that obscures previously drawn objects within its boundary.
The areas can be displayed with or without a visible boundary
(called a frame).
Revision Cloud
The REVCLOUD command allows to draw a connected series of
arcs encircling objects in a drawing to signify an area on the
drawing that has been revised.
Advanced Modification tools
AutoCAD not only allows you to draw objects easily, but also
allows you to modify objects. This section discusses five
important tools that will make your job easier:
Editing with Grips
Selecting Objects with Quick Select
Selection set by Filter
Changing Properties of Selected Objects
Grouping Objects
Editing with Grips
With grips you can move, stretch, rotate, copy, scale, and mirror
selected objects without invoking one of the regular AutoCAD modify
commands.
When you select an object with grips enabled, small squares appear at
strategic points on the object that enable you to edit the selected objects.
Grips is enabled from Options dialog box.
Options dialog box
Grips appear on the endpoints and midpoint of lines and arcs, on
the vertices and endpoints of polylines, on quadrants and the
center of circles, on dimensions, text, solids, 3dfaces, 3dmeshes,
and viewports, and on the insertion point of a block.
To edit an object using grips, select the object and then select a
grip (place the cursor over the grip and press the pick button) to
act as the base point for the editing operation. You can use
multiple grips to keep the shape of the object intact. Hold down
SHIFT as you select the grips.
Available Grip modes: Stretch, Move, Rotate, Scale, and Mirror.
Selecting Objects by Quick Select
The QSELECT command is used to create selection sets based on
objects that have or do not have similar characteristics or properties
as determined by filters. For example, you can create a selection set
of all lines that are equal to or less than 2.5 units long. Or you can
create a selection set of all objects that are not text objects on a
specific layer. The combinations of possible filters are almost
limitless.
Selection set by Filter
The FILTER command displays a dialog box that creates filter lists that
can be applied to the selection set. With the FILTER command, objects
are selected based on object properties, such as location, object type,
color, linetype, layer, block name, text style, and thickness.
Invoke the FILTER command by typing filter at the On-Screen prompt.
Changing Properties of selected objects
The Quick Properties panel lists the most commonly used
properties for selected objects.
The PROPERTIES command is used to manage and change
properties of selected objects by means of the Properties Window.
To change the objects in a selection set, invoke Properties from
the Standard toolbar.
Properties Palette
Grouping Objects
A group is a saved set of objects that can be selected and edit
together or separately as needed. Groups provide an easy way to
combine drawing elements that need to be manipulated as a unit.
The components of groups can be changed as you work by adding
or removing objects.
In some ways, groups resemble blocks, which provide another
method of combining objects into a named set. However, you can
edit individual objects in groups more easily than you can edit them
in blocks, which must be exploded first. Unlike blocks, groups
cannot be shared with other drawings.
Tools menu
Choose Object Group
On-Screen prompt
Group (ENTER)
Inquiry Commands
AutoCAD provides several commands for displaying useful
information about the objects in the drawing. The Inquiry
commands include:
List
Dblist
Measure Geometry
ID
List
The LIST command displays information about individual objects
stored by AutoCAD in the drawing database.
Dblist
The DBLIST command lists the data about all of the objects in the
drawing. It can take a long time to scroll through all the data in a
large drawing. DBLIST can, like other commands, be terminated
by canceling by pressing ESC key.
On-Screen prompt
dblist (ENTER)
Measure Geometry
The MEASUREGEOM command measures the distance,
radius, angle, area, and volume of the selected objects or
sequence of points.
The Distance option displays the distance, in the current
units, between two points selected on the screen or keyed in
from the keyboard. The information includes the horizontal
and vertical distances (delta-X and delta-Y, respectively)
between the points and the angles in and from the XY plane.
Measure Geometry
The Radius option measures the radius and diameter of a
specified arc or circle. The radius and diameter of the
specified arc or circle display at the Command prompt and
in the tooltip.
Measure Geometry
The Angle option measures the angle of a specified arc,
circle, line, or vertex.
Measure Geometry
The Area option is used to report the area, in square units,
and perimeter of a selected, closed geometric figure such as
a circle, polygon, or polyline. You may also specify a series of
points that AutoCAD considers to be a closed polygon.
Measure Geometry
The Volume option measures the volume of an object or a
defined area.
ID
The ID command is used to obtain the coordinates of a selected point.
If you do not use an Object Snap mode to select a point that is not in
the current construction plane, AutoCAD assigns the current elevation
as the Z coordinate of the point selected.
Changing System Variables
AutoCAD stores the settings (or values) for its operating
environment and some of its commands in system variables. Each
system variable has an associated type: integer (for switching),
integer (for numerical value), real, point, or text string.
Unless they are read-only, you can examine and change these
variables at the Command: prompt by typing the name of the system
variable, or you can change them by means of the SETVAR
command.