The built-in WIPEOUT command only accepts a polygonal boundary, so masking a circular area — a column, a manhole, a bolt hole on a detail — normally means drawing a many-sided polygon by hand and hoping it looks round. ROUNDMASK makes it genuinely circular.
What RoundMask does
ROUNDMASK draws a circular wipeout from a centre and radius. CIRC2MASK converts existing circles into wipeouts of the same size and properties, deleting the original circles.
The second is the one that gets used most: you have already drawn the columns as circles, and now they need to mask what is behind them.
How to use it
- Load the routine with
APPLOAD, or put it on your support file search path. - Type
ROUNDMASKand give a centre and radius, orCIRC2MASKand select existing circles. - The circles are replaced by wipeouts of the same size.
How it works
A wipeout is really an image entity with a clipping boundary. The boundary is stored as a list of DXF group 14 points expressed in normalised image space, where the image occupies a unit square running from -0.5 to +0.5 in both directions. Points at radius 0.5 from the centre of that square therefore trace a circle that exactly fills the image.
So the circle is built once, in normalised space, at a fixed resolution — and the actual size and position come from the image’s own U and V vectors, DXF groups 11 and 12, which are set to the required diameter.
That is why the result stays perfectly circular at any scale. The boundary is not a polygon sized to the object; it is a fixed shape stretched by the image vectors, so a wipeout enlarged ten times is still exactly as round as it was.
Both commands work correctly in any UCS and any view.
Notes and limits
- CIRC2MASK deletes the original circles. That is the point, but it means keeping a copy if you still need the geometry.
- Wipeouts obey draw order. If something has disappeared that should not have, check the order rather than the mask.
- Wipeout frames are controlled by WIPEOUTFRAME, not by this routine — set it to 0 to hide the frames on plot.
- One undo group covers the whole operation.
Download and details
| Name | RoundMask — create circular wipeouts, which AutoCAD cannot do natively |
| Download | RoundMask.lsp — 11.3 KB, plain AutoLISP source. Downloads directly; no zip to unpack. |
| Type | AutoCAD AutoLISP routine |
| Commands | CIRC2MASK, ROUNDMASK |
| Requires | nothing beyond a CAD platform with AutoLISP. |
| Source size | 11.3 KB, 280 lines |
| Error handling | Yes — a *error* handler restores every system variable it changed, on cancel as well as on error. |
| Undo | The whole operation is wrapped in a single undo group, so one U reverses all of it. |
| Compatibility | AutoCAD (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. |
| Author | YZ, August 2026 |
| Licence | Free to use, supplied “as is” with no warranty. |
References
- BACKDROP LISP — background masks on text rather than wipeouts on geometry
- HATCHCLEAR LISP — cutting hatch away rather than masking over it
- LAYERSTACK LISP — draw order by layer, which is what makes masks behave
- More free AutoLISP routines on this site
- Wisey’s Steel Shapes — free structural steel section drawing program