Using CHANGE command on 3d Polylines (general autocad questi

[Matthew Timion]

Hello all

I am attempting to use the CHANGE command to change elevations of a line.
I've noticed that this command only works on LWPOLYLINEs, and not POLYLINES.
LWPOLYLINEs are drawn when I use the "2dp" command, and POLYLINEs are made
when I use the 3dp command.

Is there a way I can convert my POLYLINEs to LWPOLYLINEs?

--
Matt Timion
Earthwork Calculation Services

[dcjohnson]

convertpoly is the commane your looking for. you can also set the system
variable plinetype to 2

PLINETYPE
Specifies whether AutoCAD uses optimized 2D polylines. PLINETYPE controls both
the creation of new polylines with the PLINE command and the conversion of
existing polylines in drawings from previous releases.

0 Polylines in older drawings are not converted when opened; PLINE creates
old-format polylines
1 Polylines in older drawings are not converted when opened; PLINE creates
optimized polylines
2 Polylines in older drawings are converted when opened; PLINE creates optimized
polylines

For more information on the two formats, see the CONVERT command.

PLINETYPE also controls the polyline type created with the following commands:
BOUNDARY (when object type is set to Polyline), DONUT, PEDIT (when selecting a
line or arc), POLYGON, and SKETCH (when SKPOLY is set to 1).


--
Dave C. Johnson
djohnson@wwcengineering.com
WWC Engineering
Sheridan WY.
Windows 2k2
Acad Map 5
Survcadd XML

[R.K. McSwain]

"Matthew Timion" <mtimion@dirtestimator.com> wrote

I am attempting to use the CHANGE command to change elevations of a line.
I've noticed that this command only works on LWPOLYLINEs, and not POLYLINES.
LWPOLYLINEs are drawn when I use the "2dp" command, and POLYLINEs are made
when I use the 3dp command.

3D Polylines can only be a POLYLINE entity type.
2D Polylines can either be a POLYLINE or LWPOLYLINE entity type.

PLINETYPE controls the latter.

[Matthew Timion]

This confuses me a bit as I have elevated LWPOLYLINEs and they have stayed
LWPOLYLINEs. I simply changed the "elevation" value. The difference I
imagine is that lwpolylines have a constant elevation, and polylines have
elevations for each vertex. This is obviously the thing hindering me from
using the "Change" command to elevate my 3dpolylines. Is there a way to
automatically change the polylines into lwpolylines (assuming, of course,
the polylines have a zero elevation)?

--
Matt Timion
Earthwork Calculation Services
"R.K. McSwain" <rkmcswain@yahoo.com> wrote in message
news:bfhe5o$vuk$1@update.carlsonsw.com...
"Matthew Timion" <mtimion@dirtestimator.com> wrote

3D Polylines can only be a POLYLINE entity type.
2D Polylines can either be a POLYLINE or LWPOLYLINE entity type.

PLINETYPE controls the latter.

[Jason Bly]

I'm not sure what you are ulitmately trying to accomplish, whether you want
to move a polyline elevation by a certain amount or if you just want to put
it on a constant elevation, but here's what I know.

Under Edit pulldown, 3d Entity to 2D (command: 3dto2d) will change a
polyline to lwpolyline, but it will have a constant elevation of course.
Under Edit-Change-Elevation (command: chgelev) you can bump an objects
elevation to an absolute elevation or a by a certain differential amount
(thus keeping all elevations along the polyline).

Hope this helps

Jason

"Matthew Timion" <mtimion@dirtestimator.com> wrote in message
news:bfhi1g$1tl$1@update.carlsonsw.com...

This confuses me a bit as I have elevated LWPOLYLINEs and they have stayed
LWPOLYLINEs. I simply changed the "elevation" value. The difference I
imagine is that lwpolylines have a constant elevation, and polylines have
elevations for each vertex. This is obviously the thing hindering me from
using the "Change" command to elevate my 3dpolylines. Is there a way to
automatically change the polylines into lwpolylines (assuming, of course,
the polylines have a zero elevation)?

--
Matt Timion
Earthwork Calculation Services
"R.K. McSwain" <rkmcswain@yahoo.com> wrote in message
news:bfhe5o$vuk$1@update.carlsonsw.com...
"Matthew Timion" <mtimion@dirtestimator.com> wrote

3D Polylines can only be a POLYLINE entity type.
2D Polylines can either be a POLYLINE or LWPOLYLINE entity type.

PLINETYPE controls the latter.

[R.K. McSwain]

"Matthew Timion" <mtimion@dirtestimator.com> wrote

This confuses me a bit as I have elevated LWPOLYLINEs and they have stayed
LWPOLYLINEs. I simply changed the "elevation" value. The difference I
imagine is that lwpolylines have a constant elevation, and polylines have
elevations for each vertex. This is obviously the thing hindering me from
using the "Change" command to elevate my 3dpolylines. Is there a way to
automatically change the polylines into lwpolylines (assuming, of course,
the polylines have a zero elevation)?

A POLYLINE entity whose DXF code 70 includes bit code "8" is considered a "3D Polyline" and its vertices may have different elevations (but they do not have to).

A POLYLINE entity whose DXF code 70 does not include bit code "8" is considered a "Heavy 2D Polyline" and its vertices may not have different elevations.

A LWPOLYLINE can only have a single constant elevation for all it's vertices. (This is a new entity type starting in R14)

In summary, a POLYLINE entity can be a 2D Polyline *or* a 3D Polyline, but a LWPOLYLINE can only be 2D.

[Matthew Timion]

Thanks Jason...

What I'm trying to accomplish is to use the "CHANGE" command to change
polyline's elevation based on selected text. I'm doing this with an
AutoLISP function that I've written. It turns out that the "CHANGE" command
only changes LWPOLYLINE's elevation, and not POLYLINE's. Test it yourself
and see what I mean.

I want to include code that will automatically convert all polylines to
lwpolylines so that this type of error doesn't happen.

Have survcadd commands been implimented in Autolisp routines? Can I use
"3dto2d" in AutoLISP routines with XML2?

--
Matt Timion
Earthwork Calculation Services

"Jason Bly" <jbly@marshandlegge.com> wrote in message
news:bfhk6u$2qr$1@update.carlsonsw.com...

I'm not sure what you are ulitmately trying to accomplish, whether you
want
to move a polyline elevation by a certain amount or if you just want to
put
it on a constant elevation, but here's what I know.

Under Edit pulldown, 3d Entity to 2D (command: 3dto2d) will change a
polyline to lwpolyline, but it will have a constant elevation of course.
Under Edit-Change-Elevation (command: chgelev) you can bump an objects
elevation to an absolute elevation or a by a certain differential amount
(thus keeping all elevations along the polyline).

Hope this helps

Jason

"Matthew Timion" <mtimion@dirtestimator.com> wrote in message
news:bfhi1g$1tl$1@update.carlsonsw.com...
This confuses me a bit as I have elevated LWPOLYLINEs and they have
stayed
LWPOLYLINEs. I simply changed the "elevation" value. The difference I
imagine is that lwpolylines have a constant elevation, and polylines
have
elevations for each vertex. This is obviously the thing hindering me
from
using the "Change" command to elevate my 3dpolylines. Is there a way to
automatically change the polylines into lwpolylines (assuming, of
course,
the polylines have a zero elevation)?

--
Matt Timion
Earthwork Calculation Services
"R.K. McSwain" <rkmcswain@yahoo.com> wrote in message
news:bfhe5o$vuk$1@update.carlsonsw.com...
"Matthew Timion" <mtimion@dirtestimator.com> wrote

3D Polylines can only be a POLYLINE entity type.
2D Polylines can either be a POLYLINE or LWPOLYLINE entity type.

PLINETYPE controls the latter.