How to Extend Lines to shape 2D Polyline

[Mountain_XD]

Please help me Extend Lines to Polyline. Thanks so much !

Extend Lines to Polyline.dwg

[mhupp]

You don't need a lisp for that. just the extend command.

[ScottMC]

check your 'projmode if 'extend too' entity is on a different 'Z'

I like [2]

Edited July 18 by ScottMC

[Mountain_XD]

1 hour ago, mhupp said:

You don't need a lisp for that. just the extend command.

I agree with you but what if there are a lot of polylines and lines?

[GLAVCVS]

I spoke too fast

Edited July 18 by GLAVCVS

[ScottMC]

Consider this link with multiple solutions

https://www.theswamp.org/index.php?topic=53993.0

[BIGAL]

Interesting Bricscad using "Fence" option. No code needed.

[mhupp]

19 hours ago, Mountain_XD said:

I agree with you but what if there are a lot of polylines and lines?

 

Going to have to click a little then. or use fence like BIGAL shows.

[ScottMC]

BIGAL that helps for sure! All the more inspires me to dig deeper into your posts/tips period.

[SLW210]

On 7/18/2025 at 7:31 PM, BIGAL said:

Interesting Bricscad using "Fence" option. No code needed.

 

 

AutoCAD refuses to double extend for some reason.

[SLW210]

For future reference, in the supplied .dwg, it's LWPolyline shapes not 2D Polyline shapes as in the title, there is a difference.

 

 LWPOLYLINE  Layer: "A_Dai_Coc_S_02"
                            Space: Model space
                   Color: BYLAYER    Linetype: "Continuous"
                   Handle = 167
            Closed
    Constant width     0'-0"
              area   5418979.86 square in. (37631.8046 square ft.)
         perimeter   791'-11 9/32"

          at point  X=22622'-6 5/16"  Y=176'-5 5/8"  Z=    0'-0"
          at point  X=22784'-3 15/32"  Y=141'-6 27/32"  Z=    0'-0"
          at point  X=22907'-5 13/32"  Y=279'-3 15/16"  Z=    0'-0"
          at point  X=22708'-11 1/16"  Y=378'-6 5/32"  Z=    0'-0"

 

2D Polyline 

 

                  POLYLINE  Layer: "KCS_DIM"
                            Space: Model space
                   Color: BYLAYER    Linetype: "Continuous"
                   Handle = 179
              Open
    starting width     0'-0"
      ending width     0'-0"
              area      0.00 sq in (0.0000 sq ft)
            length 2566'-5 17/32"

                  VERTEX    Layer: "KCS_DIM"
                            Space: Model space
                   Color: BYLAYER    Linetype: "Continuous"
                   Handle = 17b
                at point, X=23794'-4 1/8"  Y=-362'-5 9/32"  Z=    0'-0"
    starting width     0'-0"
      ending width     0'-0"

                  VERTEX    Layer: "KCS_DIM"
                            Space: Model space
                   Color: BYLAYER    Linetype: "Continuous"
                   Handle = 17c
                at point, X=21227'-10 19/32"  Y=-362'-5 9/32"  Z=    0'-0"
    starting width     0'-0"
      ending width     0'-0"

                  END SEQUENCE  Layer: "KCS_DIM"
                            Space: Model space
                   Color: BYLAYER    Linetype: "Continuous"
                   Handle = 17a

 

If I have time, I'll see what I can come up with.

 

[SLW210]

On 7/18/2025 at 8:04 PM, mhupp said:

 

Going to have to click a little then. or use fence like BIGAL shows.

 

Even with AutoCAD probably still pretty fast for fence, but a LISP would help.

 

I tried several things and I can't get AutoCAD 2026 to double extend as per @BIGAL's example.

[mhupp]

9 hours ago, SLW210 said:

I tried several things and I can't get AutoCAD 2026 to double extend as per @BIGAL's example.

I know he uses BricsCAD and I used it for the last 5 years when I was still working in CAD. liked it a lot more the AutoCAD. 

there are differences but mostly for the better like double extend.

[SLW210]

I just did a quick look in AutoCAD, this may be a bit tricky for me.

 

Let me get my paid to do work done and I'll do more looking.

[Tsuky]

On 7/22/2025 at 12:55 PM, SLW210 said:

I tried several things and I can't get AutoCAD 2026 to double extend as per @BIGAL's example.

It works, but the fence must pass on each side of the middle of the segment to be extended.

[SLW210]

6 hours ago, Tsuky said:

It works, but the fence must pass on each side of the middle of the segment to be extended.

I tried that everyway possible and no luck with AutoCAD 2026, if I get time I'll look through my settings again.

Might be a quirk in my AutoCAD 2026. It does seem it used to work as you say.

[BIGAL]

Here is the help for Extend it has some variables you can set may be applicable for Acad.

 

https://help.bricsys.com/en-us/document/command-reference/e/extend-command?version=V25&id=165079077042

[SLW210]

I got it now, very fast double extend now.

 

Current settings: Projection=UCS, Edge=None, Mode=Standard then Fence option.

 

If I recall you used to be able to double extend with crossing as well.

 

If I get time I'll dig a little deeper.

 

You have to be careful any extra crossings will send the extend through the closed shapes.