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How to center letters/symbols in a polyline with linetype

MMStaake
Explorer

How to center letters/symbols in a polyline with linetype

MMStaake
Explorer
Explorer

I've created a few different linetypes and some of them are centered and some aren't. Does anyone know how to fix this? Image attached. 

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vladimir_michl
Advisor
Advisor

There is no "symmetry" property, it all depends on the linetype definition. If the initial and final segment of the definition is the same, the line will behave symmetrically. For polylines, the linetype generation property will influence the style displayed at vertices.

 

Vladimir Michl, www.arkance.world  -  www.cadforum.cz

 

Simon_Weel
Advisor
Advisor

The line types are defined in the file acad.lin / acadiso.lin. You can modify the files with Notepad. See AutoCAD 2024 Developer and ObjectARX Help | About Shapes in Custom Linetypes | Autodesk

Oh, and don't forget the Linetypescale.

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Kent1Cooper
Consultant
Consultant

@vladimir_michl wrote:

.... If the initial and final segment of the definition is the same, the line will behave symmetrically. ....


That's not the way it works.  From Help [2025, but no different in earlier versions]:

The program adjusts the dash-dot sequence on an individual line so that dashes and line endpoints coincide. The pattern fits the line so that at least half of the first dash begins and ends the line. If necessary, the first and last dashes are lengthened.

 

To illustrate:

Kent1Cooper_0-1731504572940.png

The upper group use AutoCAD's HIDDEN definition, which specifies only a dash and a gap.  But the results have symmetrical start-end dash lengths.

For the lower group, I made the HIDDEN3 definition with a dash at the beginning and at the end, i.e. "initial and final segment of the definition is the same."  The result is asymmetrical, because it splits the starting pen-down and puts half of it at each end.  The Lines are drawn from left to right, and the extra half tacked onto the final dash in the definition extends the right [ending] dash lengths to longer than the left [starting] ones.

 

Linetypes like those in @MMStaake's image should be defined starting with a dash and ending with the gap concluding the space around the text or shape inclusion.  See, for example, this one of AutoCAD's, which does that:

*HOT_WATER_SUPPLY,Hot water supply ---- HW ---- HW ----
A,.5,-.2,["HW",STANDARD,S=.1,U=0.0,X=-0.1,Y=-.05],-.2

AutoCAD even made the same mistake themselves in some linetype definitions.  TRACKS has a pen-down entry at both ends:

*TRACKS,Tracks -|-|-|-|-|-|-
A,.15,[TRACK1,ltypeshp.shx,s=.25],.15

and sure enough, the result is asymmetrical:

Kent1Cooper_1-1731505517237.png

Kent Cooper, AIA
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