Loss of Style for Building Elements (Walls, Slabs, ...) and Transparency for Windows

[lvanlier]

Thanks of lot for the work done in the IFCJSON project.

I am building a platform that converts IFC to IfcJSON with IFC2JSON and stores the IfcJSON in a PostgreSQL database. Thereafter, when needed, the IfcJSON is converted back to an IFC with JSON2IFC for visualization in a standard IFC Viewer. All this works fine, except for rendition.

In most IFC Viewers, building elements (Walls, Slabs, ...) are grey and transparency of Windows is lost so that it is not possible to see through. This is also the case for the IFC files provided in the Samples (e.g. Duplex_A_20110907_optimized_roundtrip.ifc).

My project is d4su-server and the doc in https://lvanlier.github.io/. This issue is highlighted in Transform the ifcJSON to IFC

Any fix or hint for a fix will be appreciated.

[lvanlier]

The code in ifc2json4.py gets the entities from ifcModel.by_type('IfcRoot') but does not look for the IfcStyledItem elements that make the junction between material or geometry and the style.

The IfcStyledItem elements need to be added. An IfcStyledItem may reference a geometry element and this one must then also be available for being referenced.
See https://ifc43-docs.standards.buildingsmart.org/IFC/RELEASE/IFC4x3/HTML/lexical/IfcStyledItem.htm.

So there are quite a few types that need to be added and the conversion of the IfcStyledItem to json must be adapted.
The code in https://github.com/lvanlier/d4su-server/blob/main/src/local_modules/ifcjson/ifc2json4.py
implements some changes. This does not handle all possible cases, but it does the job for the conversion of Duplex_A_20110907_optimized.ifc and for others as well.