Is there an IFC approach to apply vector-based patterns, similar to a .PAT file, to objects?
If not, is .PAT schema open source?
Related, is there an approach to apply vector based patterns to Blender objects?
IfcFillAreaStyleHatching and IfcFillAreaStyleTiles is probably what you're after in the IFC world.
I don't know anyone who has implemented it.
I am debating between ignoring them and delegating styling purely to SVG CSS, but it's good to know they exist, and we should definitely try to prevent buildingSMART from removing these entities until we have determined whether or not they are useful.
I don't think you can have a vector texture in Blender (I would love to be proven wrong), but it is possible to procedurally build a texture, which I guess is similar in concept to a vector.
Busy implementing .pat-based hatching in FreeCAD, btw. Indeed would be nice to export that to ifc.. i would really like some day to try supporting 2d better too
Grease pencil seems a viable foundation for vector based patterns in Blender.
The problem is afaik, grease pencil is no "real geometry". but would we need real hatches that exist as geometry on top of objects?
I know you can convert grease pencil to curves and mesh, so it seems there is some geometry info there, in my limited understanding.
It is nice to 'snap' or 'align' to patterns sometimes (or align/snap patterns to objects), for example a running bond brick or CMU pattern, so in that sense it would be nice to 'interact' with the pattern geometry in some fashion.
@Erindale's sweet sverchok examples!:
there are some tools in Sverchok also for this question:
@yorik Concerning the .pat format, this thread on the revit forum ist currently the most backed one: https://forums.autodesk.com/t5/revit-ideas/rethink-hatch-fill-patterns/idi-p/6489965 If the .pat format is still important to maintain compatibility with dxf there oft-mentioned pyrevit addin comes with a python script that turns lines into .pat files which might be adapted to suit FreeCAD.
@wmi At Autodesk they don't really care about that forum. There is no mention of patterns on the official roadmap: https://trello.com/b/ldRXK9Gw/revit-public-roadmap
Considering they added background fills some versions ago, I don't think they will change how pattern works in the short run.