Supported IFC versions

[dominichofer]

Could you make a statement about the IFC-versions IFC++ is supporting, import and export? It looks like it's supporting IFC4Add2. Which looks like it's backwards compatible to IFC4 and IFC4Add1. But it also does a great job at importing IFC2x3. So, is IFC++ supposed to support the import of IFC2x3 or is this only based on the backward compatibility of IFC4 to IFC2x3?

I came across IfcDistributionChamberElement which has 8 parameters in IFC2x3 and 9 parameters in IFC3Add2. The 9th parameter has cardinality [0:1] but it results in a message "Wrong parameter count for entity IfcDistributionChamberElement, expecting 9, having 8.".

[loebl]

IFC++ supports only IFC4Add2 (4.0.2.0) Import of older versions is working on base of the compatibility between specifications (and possibly a few hacks in the parser, but they are rare and shouldn't be relied on). That means every entity that didn't change will still work.

In your example case the number of elements changed. The cardinality doesn't change the fact that the entity has to supply 9 attributes under IFC4. It means it can use the empty value ("$") for the 9th one.

As far as I know Core and Ressource elements are largely unchanged (chapters 5 and 8 in the spec , shared elements (chapter 6) work for the most part and domain-specific elements (chapter 7) are usually not expected to be compatible

[ifcquery]

I agree to the comment above. Most changed entities have just one more optional attribute at the end, so the parser just adds a "$" as empty value in case of a 2X3 file. That normally works fine. If not, I can fix it if you provide the example file.

If you want to write a 2X3 file, you need the class model generated for the 2X3 schema and a converter. I can do that with the class model and parser generator, please let me know when necessary.

[ariaci]

We also still need to write IFC2X3 TC1. Where can I find the class model generator to generate the source for IFC2X3 TC1? Formerly the generator was named IfcPlusPlusExtender and available using the following link: https://github.com/ifcquery/ifcplusplus/issues/41 ... but now there opens a chinese (?) page ...

Thanks in advance.

[ifcquery]

IFC4 is ISO standard since 2013, so there was plenty of time to update to IFC4. I can't think of a scenario where it makes sense to write out IFC2X3 files. The class and parser generator is not public domain, but I could generate a version of IFC++ for IFC2X3 if someone needs it.

[dominichofer]

Please don't. We ass well used to have lots of customers asking for IFC2X3. The major reasons for this was:

• They didn't know their software could also process IFC4
• They used a very old version of their software which was not IFC4 compatible
• Some contract asked explicitly for IFC2X3 Issues that can be solved if people talk to one another, or update software.

So for the love of progress, don't adopt an old standard. Move on! Update! Find an other solution and help the building industry make progress.

[ifcquery]

I totally agree ;)

[claimred]

• Speaking of supported versions, could you elaborate on differences between IFC4 ADD2 (4.0.2.0) and IFC ADD2 TC1 (4.0.2.1). Is it possible for IfcPlusPlus to claim that it supports ISO IFC schema? Or it can be generated same way as IFC2x3 TC1.

• Is it possible to get IFC4.1 (4.1.0.0) support i.e. class hierarchy like that?

The class and parser generator is not public domain, but I could generate a version of IFC++ for IFC2X3 if someone needs it.

As for IFC 2x3 TC1 code generation how do you recommend going forward with that, should one contact you by email?

Thanks!

[ifcquery]

Yes, we can discuss details via email: fbngerold (at) gmail.com

[ifcquery]

Version 4.0.2.1 and 4.0.2.0 have only tiny differences, there is just one added Type: TYPE IfcStrippedOptional = BOOLEAN; END_TYPE;

[ifcquery]

IFC4.1 (4.1.0.0) is definitely possible. We can discuss that via email too