[Bug]: Incorrect geometry color

[mezlondr]

What happened?

Hi,

I have this ifc building, which turns out to be black according to this webifc library, but it's supposed to be white:

I have extracted a small wall from the building which will hopefully make it easier to find:

bd2.zip

Version

0.74 (commit 4382da6), update: persists in 0.75

What browsers are you seeing the problem on?

No response

Relevant log output

Anything else?

I'm 99% sure this is an issue in the C++ part of the library.

[mezlondr]

Upon further digging, it seems to me the element color is given by IFCPRESENTATIONSTYLEASSIGNMENT, which is in newer version deprecated, but anyways, it assigns two styles, IFCCURVESTYLE - which is black, and IFCSURFACESTYLE - which is white.

I assume the person who designed it made it white, and also Solibri evaluated it as white, but as far as I can tell, the standard only defines that IfcStyledItem has priority over IfcPresentationStyle .(https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3/HTML/lexical/IfcRepresentationItem.htm), since both IfcCurveStyle and IfcSurfaceStyle are IfcPresentationStyle, there does not seem to be a standardized obligation to prioritize one before the other.

If that's the case and I understood it right, there is of course no bug and it's probably a mistake of the designer that just happened to work in different renderers.

As a workaround, I tried implementing weighted color mixing in the case of ambiguous colors, which at least in this case gives visually better results, although I am not sure my interpretation is correct.