Snap to 2D polyline

Firstly, what's the difference between a bog-standard polyline and a 2D polyline?

And secondly, why can't I snap to a 2D polyline? It's driving me nuts....

EDIT: I've noticed that it's not all 2D polylines that I can't snap to. I have others in the same layer, with the same properties which are fine...... ????????

Quoted from CAD Panacea:

Confused about the various polyline types that you see in AutoCAD?

From the end user perspective there are 3 polyline types listed in the PROPERTIES command, even though there are only two "entity" types.

• polyline - this is an LWPOLYLINE entity, always 2D.
  
• 2d polyline - this is a POLYLINE entity, also 2D.
  
• 3d polyline - this is a POLYLINE entity, usually 3D, with each vertex at a different elevation. It is possible to have a "3d polyline" and have each vertex at the same elevation.

If you use the LIST command on any polyline, you will only see the

entity names (POLYLINE or LWPOLYLINE).

POLYLINE entities are the original type. LWPOLYLINE entities were introduced in R14.

If PLINETYPE = 0 (zero), then the PLINE command will create POLYLINE entities.

If PLINETYPE = 1 or 2, then the PLINE command will create LWPOLYLINE entities.

To create 3d polylines, use the 3DPOLY command.

To convert between POLYLINE and LWPOLYLINE entities, use the CONVERTPOLY command.

Thanks very muc ReMark

3DPoly - Definition taken from AutoCAD Help:

"A 3D polyline is a connected sequence of straight line segments created as a single object. 3D polylines can be non-coplanar; however, they cannot include arc segments."

I'm not sure why you are having trouble snapping to some 2D polylines. Might it have something to do with the UCS orientation at the time of their construction versus its current orientation?

you should be able to use snap on 2D poly's, like Terminator said it must be your settings or something you have alterd somewhere along the line

I don't mean to bring back an old thread...but just wondering if you ever figured out why you couldn't snap to 2D polylines? I am having the same problem right now and I am getting very frustrated with it.

DM:

Are you working in 2D or 3D?

Well, it should be mostly 2D, however some of the Civil3D objects are drawn at their respective z value (such as spot elevations). All the line work should be 2D though, which is what I am wanting to snap to.

When did the problem first occur?

I have never really noticed it before, but usually the lines are just regular 'polylines' as opposed to '2D polylines'. If I explode the '2D polyline' into lines I can snap to endpoints (or anything) like normal.

Just so I am clear on this...I should be able to snap to these '2D poylines' right?

If so, maybe I should just try to restart AutoCAD and see what happens.

Well, restarting AutoCAD and my computer (thanks to Microsoft Automatic updates) did not rectify the problem. Maybe I will just have to live with exploding them and converting to regular polylines.

To convert between POLYLINE and LWPOLYLINE entities, use the CONVERTPOLY command.

you dont have to explode, try this as remark posted earlier

ahh yes...much better option to exploding, thanks for bringing that back up.

You maybe are using some lisp that is changing your settings.
This is happening with Polyline when "Polylinetype" is set wrong. Type "Polylinetype" then set the value to 1. Now you can snap to it, no need to explode or use "convertpoly" every time you draw