Drawing and Editing Polylines and Splines Chapter 16

Drawing and Editing Polylines and Splines Chapter 16
Sacramento City College EDT 310 EDT Chapter 16 - Drawing and Editing Polylines and Splines

EDT 310 - Chapter 16 - Drawing and Editing Polylines and Splines
Objectives Use the PLINE command to draw polylines and polyarcs. Edit existing polylines with the PEDIT command. Describe the function of each PEDIT command option. Use the EXPLODE command to change polylines into individual line and arc segments. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Objectives Draw and edit spline curves. Create a polyline boundary. EDT Chapter 16 - Drawing and Editing Polylines and Splines

The PLINE Command EDT Chapter 16 - Drawing and Editing Polylines and Splines

PLINE Command The PLINE command can be accessed by: Picking the Polyline button in the Draw toolbar OR Selecting Polyline from the Draw pull-down menu Type PL or PLINE at the Command: prompt. EDT Chapter 16 - Drawing and Editing Polylines and Splines

PLINE Command - The Arc option
EDT Chapter 16 - Drawing and Editing Polylines and Splines

PLINE Command The Arc option of the PLINE command Is similar to the ARC command The PLINE Width and Halfwidth options can be used to set an arc width. The arc width can range from 0 up to the radius of the arc. EDT Chapter 16 - Drawing and Editing Polylines and Splines

PLINE Command A polyline arc with different end widths is drawn by accessing the Width option and changing the width values. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Drawing a Continuous Polyline Arc
A polyline arc continued from a previous line or polyline is tangent to the last object drawn. The arc's center is determined automatically You can pick a new center. EDT Chapter 16 - Drawing and Editing Polylines and Splines

If a straight polyline is continued from a polyline arc, the arc's tangent direction remains the same as that of the previous line, arc, or polyline. This may not be what you want. Specify a different setting with one of the PLINE Arc options. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Arc Options: Angle Center Close Direction Radius Second pt (second point). EDT Chapter 16 - Drawing and Editing Polylines and Splines

Specifying the Included Angle
Angle option You can specify the angle for a PLINE arc by using the Angle option. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Center option When a polyline arc is continued from a drawn object, the center point is calculated automatically. You can to pick a new center point. The CEnter option allows you to specify a new center point for the arc. EDT Chapter 16 - Drawing and Editing Polylines and Splines

If A is entered, the next prompt is: Specify included angle: (enter an included angle and press [Enter]) If L is entered, the next prompt is: Specify length of chord: (enter a chord length and press [Enter]) EDT Chapter 16 - Drawing and Editing Polylines and Splines

The Direction Option The Direction option changes the bearing of the arc. It changes the default option of placing a polyline arc tangent to the last polyline, arc, or line. The Direction option functions much like the Direction option of the ARC command. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Drawing a Polyline Arc by Radius
Radius Option Polyline arcs can be drawn by giving the arc's radius. Enter the Radius option inside the PLINE Arc command. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Three-Point Polyline Arc

A three-point polyline arc can be drawn by using the Second pt option. EDT Chapter 16 - Drawing and Editing Polylines and Splines

The CLose option adds the last segment to close a polygonal shape. Used inside the PLINE Arc command sequence closes the shape with a polyline arc segment, rather than a straight polyline. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Two letters are required CL = CLose CE = CEnter option. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Presetting Polyline Widths The PLINEWID System Variable

Presetting Polyline Widths
The PLINEWID system variable Sets the constant width for polylines. To change a PLINE width Enter PLINEWID at the Command: prompt and enter a new value. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Presetting Polyline Widths
Polygons are NOT affected by the PLINEWID system variable. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Polylines are drawn as single segments. Even though you draw connecting segments, AutoCAD puts them all together. The result is one polyline treated as a single object. EDT Chapter 16 - Drawing and Editing Polylines and Splines

When editing a polyline, you must Edit it as one object OR Divide it into its individual segments. This method destroys the PLINE (!) Not recommended. EDT Chapter 16 - Drawing and Editing Polylines and Splines

The PEDIT (PE) command is accessed by: Picking the Edit Polyline button from the Modify II toolbar OR By typing PE or PEDIT at the Command: prompt, By selecting Polyline from the Modify pull-down menu. EDT Chapter 16 - Drawing and Editing Polylines and Splines

PEDIT You can also select a polyline and then right-click in the drawing area to display a shortcut menu. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Use the pick box to select a polyline to be edited. If you use the pick box on a wide polyline, you must pick it on the edge of a polyline segment, rather than in the center. EDT Chapter 16 - Drawing and Editing Polylines and Splines

If the object you select is a line or arc object (not a polyline), the following message is displayed: Object selected is not a polyline Do you want to turn it into one? <Y> Entering Y or pressing [Enter] turns the selected object into a polyline. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Join Option Allows a group of connected lines and arcs can be turned into a continuous polyline. EDT Chapter 16 - Drawing and Editing Polylines and Splines

There is no default option for the PEDIT command You must enter one of the options. Pressing [Enter] returns you to the Command: prompt. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Opening and Closing a Polyline

Open PLINEs can be Closed. Closed PLINEs can be Opened. hese functions are performed with the Open and Close options of the PEDIT command. EDT Chapter 16 - Drawing and Editing Polylines and Splines

If the PLINE is OPEN It can only be CLOSED If the PLINE is CLOSED It can only be OPENed AutoCAD displays only the appropriate option – NOT both options. EDT Chapter 16 - Drawing and Editing Polylines and Splines

The Open option is not displayed if you select a polyline that was closed by manually drawing the final segment. It is only available if the polygon was closed using the Close option of the PLINE command. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Joining Polylines to Other Polylines

Join Option Allows polylines, lines, and arcs that share an EXACT endpoint can be joined to create a single polyline. AutoCAD computes line vertices to 25 decimal places Lines may appear to have the same endpoints, BUT in reality, do NOT. You CANNOT join objects with PEDIT unless the endpoints match EXACTLY. EDT Chapter 16 - Drawing and Editing Polylines and Splines

This option works only if the polyline and other existing objects meet exactly. They cannot cross. There cannot be any spaces or breaks between the objects. Select each object to be joined EDT Chapter 16 - Drawing and Editing Polylines and Splines

To get the endpoints to match EXACTLY You may have to MOVE an object Turn OSNAP on And MOVE the object using the ENDPOINT OSNAP to get the endpoints aligned. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Changing the Polyline Width

Changing the Polyline Width
The Width Option of the PEDIT command allows you to change a polyline width to a new width. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Editing a Polyline Vertex

The Edit vertex option of the PEDIT command is used to Edit polyline vertices and Points of tangency. EDT Chapter 16 - Drawing and Editing Polylines and Splines

is where straight polyline segments meet. A point of tangency is where straight polyline segments or polyline arcs join other polyline arcs. EDT Chapter 16 - Drawing and Editing Polylines and Splines

When you enter the Edit vertex option, an "X" marker appears on screen at the first polyline vertex or point of tangency. EDT Chapter 16 - Drawing and Editing Polylines and Splines

The Edit vertex option has 10 options Next Previous Break Insert Move Regen Straighten Tangent Width eXit EDT Chapter 16 - Drawing and Editing Polylines and Splines

Next Moves the "X" marker on screen to the next vertex or point of tangency on the polyline. Previous Moves the marker to the previous vertex or point of tangency on the polyline. Break Breaks a portion out of the polyline. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Insert Adds a new polyline vertex. Move Moves a polyline vertex to a new location. Regen Generates the revised version of the polyline. Straighten Straightens polyline segments. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Tangent Specifies a tangent direction for curve fitting when using the PEDIT Fit option. Width Changes a polyline segment width. eXit Returns the PEDIT command prompt. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Only the current point identified by the "X" marker is affected by editing functions. The marker is moved Clockwise using the Next option (N) Counterclockwise using the Previous option. (P) EDT Chapter 16 - Drawing and Editing Polylines and Splines

Making Breaks in a Polyline

Making Breaks in a Polyline
Break option Breaks out a portion of a polyline Use the Next or Previous option to move the "X" marker to the correct vertex. AutoCAD accepts the highlighted vertex as the first break point. Move the marker to the vertex you want to designate as the second break point. Enter G for Go. AutoCAD removes the portion of the polyline between the two selected points. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Inserting a New Polyline Vertex

Inserting a New Polyline Vertex
To add a new vertex Use the Insert vertex option. Use the Next or Previous option to locate the vertex next to where you want the new vertex to be. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Moving a Polyline Vertex

Moving a Polyline Vertex
To move a polyline vertext Use the Move vertex option. This option is similar to the Insert option. Place the "X" marker on the vertex you want to move with Next or Previous. Then, enter the Move option and Specify the new location. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Straightening Polyline Segments or Arcs

Straightening Polyline Segments or Arcs
The Straighten vertex option allows you to straighten polyline segments or arcs between two points. Place the "X" marker on the vertex you want to move with Next or Previous. Then, enter Straighten option. If the 'X" marker is not moved before G is entered, AutoCAD straightens the segment from the first marked point to the next vertex. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Changing Polyline Segment Widths

To change the width of an individual polyline segment Use the Width vertex option Move the "X" marker to the beginning vertex of the segment to be altered. Enter the Width option and Specify the new width. EDT Chapter 16 - Drawing and Editing Polylines and Splines

The starting width default value is the current width of the segment to be changed. The ending width default value is the same as the revised starting width. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Making Smooth Curves EDT Chapter 16 - Drawing and Editing Polylines and Splines

Making Smooth Curves You can convert a polyline into a series of smooth curves. Example: a graph. A graph may show a series of plotted points as a smooth curve rather than straight segments. This process is called curve fitting. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Making Smooth Curves Example: a curved landscape border. The landscape border can be drawn with straight polyline segments and then converted to a smooth curve. If the curvature is not correct, Decurve the line Adjust the verticees Recurve the line EDT Chapter 16 - Drawing and Editing Polylines and Splines

Making Smooth Curves To curve a PLINE Use the PEDIT Fit option Spline option. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Making Smooth Curves The Fit option allows you to construct pairs of arcs passing through control points. You can specify the control points Closely spaced control points produce a smooth curve. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Making Smooth Curves If the resulting curve does not look like what you had anticipated, Decurve the PLINE Enter the Edit vertex option. Make changes using the various vertex editing options as necessary. EDT Chapter 16 - Drawing and Editing Polylines and Splines

The PEDIT Spline Option

The PEDIT Fit option, Causes the resulting curve to pass through polyline vertices. EDT Chapter 16 - Drawing and Editing Polylines and Splines

makes the resulting curve pass through the first and last control points or vertices only. The curve pulls toward the other vertices (but does not pass through them). EDT Chapter 16 - Drawing and Editing Polylines and Splines

The SPLINETYPE system variable determines whether AutoCAD draws cubic or quadratic curves. Default = 6 = cubic curve 5 = quadratic curve EDT Chapter 16 - Drawing and Editing Polylines and Splines

Straightening All Polyline Segments

Straightening All Polyline Segments
The PEDIT Decurve option returns a polyline edited with the Fit or Spline options to its original form. You can also use the Decurve option to straighten the segments of a polyarc. EDT Chapter 16 - Drawing and Editing Polylines and Splines

The Undo Option EDT Chapter 16 - Drawing and Editing Polylines and Splines

The Undo Option If you make a mistake while editing a polyline, use the Undo option. Using the Undo option more than once allows you to step backward through each option used. Press [Enter] to return to the Command: prompt. EDT Chapter 16 - Drawing and Editing Polylines and Splines

The Undo Option The UNDO command can also be used at the Command: prompt to undo the effects of the last PEDIT command. EDT Chapter 16 - Drawing and Editing Polylines and Splines

The SPLINE Command EDT Chapter 16 - Drawing and Editing Polylines and Splines

The SPLINE Command The SPLINE command is used to create a special type of curve called a “non-uniform rational B-spline” (NURBS). A NURBS curve is a “true spline”. EDT Chapter 16 - Drawing and Editing Polylines and Splines

The SPLINE Command To access the SPLINE command: Pick SPLINE button in the Draw toolbar OR Pick SPLINE from the Draw pull-down menu. Type SPL or SPLINE at the the Command: prompt. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Drawing Closed Splines
Use the Close option to draw a closed spline. EDT Chapter 16 - Drawing and Editing Polylines and Splines

The Fit Tolerance Specification
Different results can be achieved when drawing splines by altering the specifications used with the Fit Tolerance option. EDT Chapter 16 - Drawing and Editing Polylines and Splines

Drawing and Editing Polylines and Splines Chapter 16

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Drawing and Editing Polylines and Splines Chapter 16

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