What is a LWPolyline

[Tiger]

Hai!

 

This is probably an easy question for those that have been around longer than me, or I am just tired, either way, I am confused.

 

What is a LWPOLYLINE? What makes it 'LW'? Why would one use one? How can one draw one?

 

TIA!

[ReMark]

A lightweight polyline (lwpolyline) is defined in the drawing database as a single graphic entity. The lwpolyline differs from the old-style polyline, which is defined as a group of subentities. Lwpolylines display faster and consume less disk space and RAM.

 

Source: AutoCAD 2013 Help file.

[Patrick Hughes]

LWPOLYLINES were introduced in R14 - according to my reference material they use an optimized format that saves memory and disk space. I'm not exactly sure how they are defined but they are controlled with the PLINETYPE system variable (at least in R14).

[Patrick Hughes]

Beat me by this >

[Tiger]

So, okey... but.. what are they? Is the LWPOLYLINE what we normally call a POLYLINE or is it something else?

[ReMark]

A 2D polyline is now referred to as a LWPOLYLINE. Draw a polyline and do a LIST on it. Funny thing both Quick Properties and Properties will both refer to it as a polyline.

[dbroada]

my understanding is that it is basically a 2D polyline.

 

If you look at its properties in VBA and I assume the others, a drawn POLYLINE shows as a LWPOLYLINE.

[dbroada]

Beat me by this >me too

 

.

[ReMark]

You drink 10 cups of coffee before 10 a.m. and you'd be speedy too!

[dbroada]

before 10? its 16:20 here (and probably 17:20 for Tiger)

[eldon]

If you draw a polyline, then when listed it calls itself an LWPOLYLINE, but shows up in Properties as a Polyline.

 

If you now convert the polyline using CONVERTPOLY to a Heavy polyline, when listed it calls itself a POLYLINE, but shows up in Properties as a 2D Polyline.

 

Not absolutely logical to the ordinary person

[Tiger]

Uh... no, not absolutely logical... but I can be reasonably certain when the client is talking about LWpolyline, he is talking about a normal polyline..

 

Eldon, heavy and light? What.. why..how... I am to young for this!!

 

 

 

Updating: ok, reading a bit about it. A Heavy Polyline is the older version of the polyline, it contains info about start and end of all entities, so one node contains the info about both line-ends that connect to that node. A Light polyline is the ..err lighter version with only info about one node in the one node.

 

And now, that I have read that, I understand ReMarks first post

[ReMark]

You do? Could you explain it to us?

[eldon]

but I can be reasonably certain when the client is talking about LWpolyline, he is talking about a normal polyline..

 

The client may have got hold of some technical words to make as if he knows about it.

 

 

 

Eldon, heavy and light? What.. why..how... I am to young for this!!

 

I think it is all to do with performance enhancement.

[eldon]

In fact it all becomes much clearer when both types are listed, and you can see how much more information is stored with the Heavy Polyline

 

 

LWPOLYLINE Layer: "0"

Space: Model space

Handle = 2D

Open

Constant width 0.0000

area 16.2907

length 12.0000

 

at point X= 37.4603 Y= 29.9092 Z= 0.0000

at point X= 41.8667 Y= 32.2722 Z= 0.0000

at point X= 47.1998 Y= 27.7380 Z= 0.0000

 

Heavy Polyline

POLYLINE Layer: "0"

Space: Model space

Handle = 2D

Open

starting width 0.0000

ending width 0.0000

area 16.2907

length 12.0000

 

VERTEX Layer: "0"

Space: Model space

Handle = 2E

at point, X= 37.4603 Y= 29.9092 Z= 0.0000

starting width 0.0000

ending width 0.0000

 

VERTEX Layer: "0"

Space: Model space

Handle = 2F

at point, X= 41.8667 Y= 32.2722 Z= 0.0000

starting width 0.0000

ending width 0.0000

 

VERTEX Layer: "0"

Space: Model space

Handle = 30

at point, X= 47.1998 Y= 27.7380 Z= 0.0000

starting width 0.0000

ending width 0.0000

 

END SEQUENCE Layer: "0"

Space: Model space

PlotStyleName: ByLayer

Handle = 31

 

[dbroada]

does that mean a polyline with various widths will show as a heavy polyline?

 

I know I could answer myself but I am away from AutoCAD until I get to work tomorrow.

[Tiger]

Nope,, still a LWPoly. I can convert it though to a HWPoly.

 

[dbroada]

thanks Tiger, saves me the problem of remembering what I was going to do when I got in this morning.

[Tiger]

Haha, you're welcome!

[Debalance]

In order to reduce the size of a drawing is always better to use LWPOLYLINE instead 2DPOLYLINE.

Edited November 2, 2013 by Lazer