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STRINGDIM LISP: Architectural String Dimensioning

August 6, 2026

STRINGDIM puts a run of dimensions along one unbroken line, with oblique ticks at each point and the figure centred in each gap — the way a floor plan is dimensioned, and the way AutoCAD’s own DIMCONTINUE does not do it.

What StringDim does

DIMCONTINUE makes one dimension object per gap. Each carries its own dimension line and its own pair of ticks, so every internal point ends up with two ticks drawn on top of each other and the line is a row of segments that never quite meet. Zoom in on a plotted drawing and it shows.

Here the line is drawn once, end to end, and each tick is drawn once.

The trade is that these are lines and text rather than dimension objects, so they do not update if the plan moves. That is the accepted bargain for this style of dimensioning, and it is why the routine exists.

How to use it

  1. Load the routine with APPLOAD, or put it on your support file search path.
  2. Type STRINGDIM.
  3. Set the line the string runs along.
  4. Pick wall faces and openings in order. Press Enter to finish.

How it works

Points are projected square onto the dimension line. You pick wall faces and openings wherever they happen to be; every point is then projected onto the line, so the string stays perfectly straight even if the things being dimensioned are not quite in line — which on a survey of an existing building they never are.

Extension lines are drawn from where you picked to the dimension line, so it stays clear what each tick refers to.

A narrow gap gets its figure below the line. A 100 mm upstand between two openings cannot hold its own figure, so those are written underneath instead, clear of the ticks. The test is the estimated width of the text against the width of the gap.

Text is placed with its height and rotation set explicitly. Handing a point, a rotation and a string to the TEXT command works when the current style has a fixed height, but when the style height is 0 — the usual setting — AutoCAD asks for a height first and swallows the rotation as the height. The text then comes out at whatever angle the string happened to look like.

Each figure is placed at the angle of its own gap, measured between the two points it spans, not at an angle taken once from the first pair and reused down the run.

The object snap you had set is left alone, and CMDECHO is restored on the way out rather than left at 0 for the rest of the session.

Notes and limits

  • These are lines and text, not dimension objects. They do not associate and they do not update.
  • Figures that will not fit go below the line automatically.
  • Pick in order along the run.
  • One undo group covers the whole string.

Download and details

NameStringDim — one continuous run of architectural dimensions
DownloadStringDim.lsp — 13.6 KB, plain AutoLISP source. Downloads directly; no zip to unpack.
TypeAutoCAD AutoLISP routine
CommandSTRINGDIM
Requiresnothing beyond a CAD platform with AutoLISP.
Source size13.6 KB, 282 lines
Error handlingYes — a *error* handler restores every system variable it changed, on cancel as well as on error.
UndoThe whole operation is wrapped in a single undo group, so one U reverses all of it.
CompatibilityAutoCAD (any release with AutoLISP), BricsCAD, ZWCAD, GstarCAD, ProgeCAD and other IntelliCAD-based platforms. AutoCAD LT needs a LISP enabler. No .NET, no ObjectARX, no installer.
AuthorYZ, August 2026
LicenceFree to use, supplied “as is” with no warranty.

References

  • DIMCENTRE LISP — centring figures that have drifted
  • DIMCLASH LISP — finding dimension text that overlaps
  • QUICKSPAN LISP — measuring a span without dimensioning it
  • More free AutoLISP routines on this site
  • Wisey’s Steel Shapes — free structural steel section drawing program

Filed Under: AutoLISP Routines

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