Transcript Polylines.ppt
Introduction to Polylines
Sacramento City College Engineering Design Technology Introduction to Polylines 1
Polylines
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Polylines
The term polyline is composed of the words "poly" and "line." Poly means many. Introduction to Polylines 3
Polylines
A polyline is A single object that can be Made up of one or more varied-width line segments.
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The PLINE Command
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Polylines
Polylines are drawn with the PLINE command.
The TRACE command, is similar to the PLINE command.
Both commands can be used to draw thick lines.
PLINE has numerous advantages over TRACE Introduction to Polylines 6
Polylines
Polylines advantages over normal lines: 1. Polylines can be drawn as thick or tapered lines.
2. Polylines are more flexible than lines drawn with the TRACE command.
3. Polylines can be any linetype.
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Polylines
4. Polylines can be edited.
5. Closed polygons can be drawn.
6. The area or perimeter of a polyline object can be determined easily.
7. Arcs and straight lines of varying thickness can be joined as single objects.
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Polylines
The PLINE command is similar to the LINE command. But All segments of a polyline are treated as a single object.
Lines drawn with the LINE command, are individual segments.
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Polylines
To draw a polyline, Pick the Polyline button from the Draw toolbar OR Pick Polyline from the Draw pull-down menu OR Type PL or PLINE at the Command: prompt: Introduction to Polylines 10
Polylines
Command: PL or PLINE Specify start point: (select a point) Current line-width is 0.0000
Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: (select the next point) Press [Enter] to end the PLINE command and return to the Command: prompt.
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Polylines
A line width of 0.0000 produces a line of minimum width.
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Setting the Polyline Width
To adjust the Width of a PLINE Use the Width option after you enter the PLINE command to change the line width, and have selected the first point of the PLINE.
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Polyline Options
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Polyline Options
Polyline Options Width Halfwidth Length Undo Introduction to Polylines 15
Setting the Polyline Width
Width option Specify the starting and ending widths of the line. The starting width value that you specify becomes the default setting for the ending width. To keep the line the same width, press [Enter] at the second prompt.
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Setting the Polyline Width
If a tapered line is desired, enter different values for the starting and ending widths.
Starting Width = 0.0000
Introduction to Polylines Ending Width = 1.0000
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Halfwidth Option
Halfwidth option Allows you to specify the width of the polyline from the center to one side.
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Length Option
Length option
Not intuitive
Allows you to draw another polyline having the same angle as the previous polyline.
To use: After drawing a polyline: Reissue the PLINE command Pick a starting point. Enter the Length option Give the desired length.
The 2 nd PLINE will be parallel to the first PLINE.
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Undoing Previously Drawn Polylines
Undo option Use while inside the PLINE command Erases the last polyline segment drawn. Enter U at the prompt line and then press [Enter] Each time you use the Undo option, another polyline segment is erased. Introduction to Polylines 20
Undoing Previously Drawn Polylines
The cursor remains attached to the end of the polyline segment that was drawn before the undone segment. You can now continue to draw additional polyline segments OR Type U and press [Enter] again to undo another segment.
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Undoing Previously Drawn Polylines
Undo Option You can use the Undo option to remove all of the polyline segments up to the first point of the polyline.
The segments are removed in reverse order (from the order in which they were drawn).
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The U Command
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The U Command
The U command works in much the same way. The U Command is not the Undo option of the PLINE command.
The U command can be used to undo any previous commands.
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The U Command
To execute the U command: Pick the Undo button from the Standard toolbar OR Pick Undo from the Edit pull-down menu OR Pressing the [Ctrl]+[Z] key combination OR Enter U at the Command: prompt. Introduction to Polylines 25
The U Command
The U command can also be activated by: Right-clicking in the drawing area.
Selecting Undo from the shortcut menu.
AutoCAD gives you a message indicating which command was undone: Command: U PLINE Command: Introduction to Polylines 26
The U Command
You can only undo one command at a time.
Repeated UNDO’s can be executed.
The UNDO command, Has more options than the U command Is more versatile than the U command.
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The REDO Command
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The REDO Command
The REDO command is used to bring back objects that were erased with the UNDO and U commands.
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The REDO Command
Enter REDO at the Command: prompt OR Pick Redo from the Edit pull-down menu OR Press the [Ctrl]+[Y] key combination OR Pick the Redo button from the Standard toolbar to activate the command.
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The UNDO Mark
The REDO command works only immediately after undoing something.
REDO does not bring back polyline segments that were removed using the Undo option of the PLINE command.
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The TRACE Command
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The TRACE Command
To draw thick lines, the TRACE command can be used instead of the PLINE command.
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The TRACE Command
To use the TRACE command: Enter TRACE at the Command: prompt.
Specify the trace width.
Select points as you would with the LINE command.
The trace width is stored in the TRACEWID system variable.
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The TRACE Command
Command: TRACE Specify trace width
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The TRACE Command
The “problems” with TRACE are The previous trace segment is not drawn on screen until the next endpoint is specified.
There is no close option with the TRACE command.
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Filling Polylines and Traces The FILL Command
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The FILL Command
Traces and polylines can be Filled in, or Shown as an outline.
These functions are controlled by the FILL command.
The FILL command has two modes, ON and OFF.
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The FILL Command
Command: FILL Enter mode [ON/OFF]
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The FILL Command
After turning FILL off, REGEN to have the fill removed.
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The FILL Command
FILL on May slow down your computer.
If you have many wide polylines or traces in a drawing, keep FILL mode turned off.
This saves time when redrawing, regenerating, or plotting a check copy of the drawing.
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The UNDO Command
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The UNDO Command
The UNDO command is different from the U command.
The UNDO command offers several options that allow you to undo a single command or a number of commands at once.
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The UNDO Command
The command sequence is as follows: Command: UNDO Enter the number of operations to undo or [Auto/Control/BEgin/End/Mark/Back]: Introduction to Polylines 44
The UNDO Command
The default option allows you to designate the number of previous command sequences you wish to remove.
If you enter 1, the previous command sequence is removed. If you enter 2, the previous two command sequences are removed.
AutoCAD tells you which commands were undone with a message after you press [Enter].
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The UNDO Command
Command: UNDO Enter the number of operations to undo or [Auto/Control/BEgin/End/Mark/Back]: 2 PLINE LINE Command: Introduction to Polylines 46
The UNDO Command
There are several other types of undo operations that can be performed with the UNDO command.
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The UNDO Command - Auto Option
The Auto option can be turned on or off.
When Auto option is on, any commands that are part of a group and used to perform a single operation are removed together. When a command contains other commands, all of the commands in that group are removed as one single command. The Auto option is on by default.
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The UNDO Command - Auto Option
If Auto is turned off, each command in a group of commands is treated individually.
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The UNDO Command - Control Option
The Control option allows you to specify how many of the UNDO command options you want active. You can even disable the UNDO command altogether.
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The UNDO Command - Control Option
To use the Control option: Enter C after issuing the UNDO command: Enter the number of operations to undo or [Auto/Control/BEgin/End/Mark/Back]: C Enter an UNDO control option [All/None/One]
The UNDO Command - All Option
The All suboption keeps the full range of UNDO command options active. All is the default setting.
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The UNDO Command - None Option
The None suboption disables the U and UNDO commands.
When disabled, and the U command is entered, the following prompt appears: Command: U U command disabled. Use UNDO command to turn it on This prompt indicates how to reactivate the U and UNDO commands.
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The UNDO Command - Auto Option
If you type UNDO at the Command: prompt, the following appears: Command: UNDO Enter an UNDO control option [All/None/One]
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The UNDO Command - One Option
Enter 0 for the One suboption. This setting limits UNDO to one operation only. Command: UNDO Control/
The Auto Option
Type C at the Control/
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The Begin and End Options
The BEgin and End options of the UNDO command are used together to perform several undo operations at once. They allow you to group a series of commands and treat the entire group as a single command.
Once the group is defined, the U command is then used to remove the commands that follow the BEgin option but precede the End option.
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The Begin and End Options
These options are useful if you can anticipate the possible removal of several commands that are entered consecutively.
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The Begin and End Options
For example, to undo the next three commands: Command: UNDO Enter the number of operations to undo or [Auto/Control/BEgin/End/Mark/Back]: BE Command: L or LINE Command: PL or PLINEJ Command: L or LINE-I Command: UNDO Enter the number of operations to undo or [Auto/Control/BEgin/End/Mark/Back]: EJ Command: U Introduction to Polylines 59
The Begin and End Options
The U command undoes the three commands that were executed in the previous sequence. The BEgin option must precede the command sequence The End option must immediately follow the last command to be undone.
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The UNDO Mark
The UNDO Mark option allows you to insert a "marker" in the undo file. The UNDO Back option then enables you to delete commands "back" to the marker.
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The UNDO Mark
If you do not want certain work to be undone by the Back option, enter the Mark option after completing the work: Command: UNDO Enter the number of operations to undo or [Auto/Control/BEgin/End/Mark/Back]: Mj Command: Introduction to Polylines 62
The UNDO Mark
If you decide to remove any work, reissue the UNDO command and enter the Back option. This will undo everything back to the marker: Command: UNDO Enter the number of operations to undo or (Auto/Control/BEgin/End/Mark/Back]: B Introduction to Polylines 63
The UNDO Mark
If no marks have been entered, this undoes everything in the entire drawing!
AutoCAD questions your choice with the following message: This will undo everything. OK?
The UNDO Mark
If you want everything that you have drawn and edited to be undone, press [Enter].
If not, enter N or NO and press [Enter], or press the [Esc] key.
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The UNDO Mark
CAUTION Be very careful when using the UNDO Back option. Entering this option undoes everything in the entire drawing. You can bring back what you have undone if you type REDO at the Command: prompt and press [Enter] immediately after using the UNDO Back option.
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The UNDO Mark
If you use any other command, even REDRAW, after using UNDO Back, the drawing is lost forever !
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The UNDO Mark
The REDO command can be used to restore commands removed with UNDO.
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The UNDO Mark
The UNDO Mark option can be used to assist in the design process.
If you are working on a project and have completed a portion of the design, mark that spot with the Mark option and then begin work on the next design phase. If anything goes wrong with this part of the design, use the UNDO Back option to remove everything back to the mark.
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