ACAPI_Element_Change with libInd swap on IFC-imported door — does element GUID survive?

CritZer0 — Tue, 16 Jun 2026 19:20:46 GMT

We're working on an add-on that converts IFC-imported door and window elements into native parametric ArchiCAD library objects programmatically. I've been able to do this manually by setting up a door in the door tool that matches the correct size of the door, then injecting the properties into the neutral IFC door object that was merged into the PLN.

Our approach: call ACAPI_Element_Change on an IFC-imported door element, masking openingBase.libInd to a valid native library part index, then writing openingBase.width and openingBase.height. This appears to be what the UI's "Inject Element Settings" (Opt+Cmd+Click) does internally.

Three questions:

1. Does ACAPI_Element_Change with a libInd swap on an IFC-imported element preserve the element's ArchiCAD GUID — and therefore any attached custom properties?

2. Is this the correct programmatic equivalent of "Inject Element Settings," or is there a dedicated API path for this operation?

3. Are there known restrictions or side effects when calling ACAPI_Element_Change on IFC-imported elements specifically, versus native elements?

Further update with precise findings:

After `SwapLibraryPart` via `ACAPI_Element_Change`:

- The wall opening (wallhole polygon) retains original IFC dimensions and is not recut

- `ACAPI_Element_GetGDLParameters` fails entirely on the element

- The element appears to be in an intermediate state — geometry correct, but locked

The UI `Opt+Cmd+Click` "Inject Element Settings" resolves all three issues simultaneously.

Questions:

1. What is the programmatic equivalent of "Inject Element Settings" — specifically the call that switches an IFC-imported door from IFC-driven to GDL-driven mode?

2. Does this involve `ACAPI_Element_Change` with `API_DoorType` + `openingBase` mask, or a separate IFC detach call?

3. After the mode switch, does ArchiCAD automatically recalculate IFC attributes (`OverallWidth`/`OverallHeight`) from GDL parameters on export?

AC29, DevKit 29.3100. Thanks in advance.

Operating system used: Mac Apple Silicon Tahoe 26.5.1

Re: ACAPI_Element_Change with libInd swap on IFC-imported door — does element GUID survive?

CritZer0 — Tue, 16 Jun 2026 19:20:57 GMT

Final update — root cause identified:

IFC-imported doors have `ParameterTakesPrecedence = FALSE` and `Sizeable = FALSE` as IFC boolean attributes. These prevent GDL parameters from controlling dimensions or the wall opening.

Is there a C++ API call to set these two IFC boolean attributes programmatically on an imported door element?

Is it `ACAPI_Element_SetIFCAttribute` or part of the IFC Properties API?

Re: ACAPI_Element_Change with libInd swap on IFC-imported door — does element GUID survive?

Tamas Polyak — Thu, 18 Jun 2026 15:21:55 GMT

Hi,

I've entered it as a support issue, and asked a developer to look into it.

Regards,

Tamás

topic Re: ACAPI_Element_Change with libInd swap on IFC-imported door — does element GUID survive? in Archicad C++ API

ACAPI_Element_Change with libInd swap on IFC-imported door — does element GUID survive?

Re: ACAPI_Element_Change with libInd swap on IFC-imported door — does element GUID survive?

Re: ACAPI_Element_Change with libInd swap on IFC-imported door — does element GUID survive?