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by theoryshaw on 30 May 2020, edited 5 Sep 2020
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+1 votes
Ongoing Results: https://github.com/OpeningDesign/FreeMVD_WorkFlow/blob/master/IFC_roundtrip_specifications.md#extrusions_circles
Test Files: https://github.com/OpeningDesign/FreeMVD_WorkFlow/tree/master/Specifications_Test_Files/Extrusions_Circles
FreeMVD: Are experiments on how well certain objects roundtrip in/out of various BIM applications. We are always looking for volunteers, from other BIM applications, to add their results to these tests. If you can participate, ping @yorik or @theoryshaw and they can give you Github push privileges.
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by theoryshaw on 21 Jun 2020
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BlenderBIM: circles are faceted
https://gitlab.com/osarch/FreeMVD_WorkFlow/-/commit/d265a26649cd843c56fcc449952bf44c7ef03cbf
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by Moult on 21 Jun 2020
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Circles will always be faceted in Blender, I think, it's just the nature of meshes, but when I build support for it, I do plan to retain the appropriate circle properties, which is the important part.
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by Moult on 17 Aug 2020
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+1 votes
The BlenderBIM Add-on should now support importing circle profiles: https://github.com/IfcOpenShell/IfcOpenShell/commit/75b34b6a952771702eaf546d1a7149be90967f39
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by theoryshaw on 17 Aug 2020
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Cool. Just import, or export too?
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by yorik on 25 Aug 2020
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blender has no real support for curves. there are nurbs, but it's not really used for modelling, it's more there to define animation paths and things like that. But it's not necessarily a problem. I see this like bitmap vs vector drawing. sometimes one is best, sometimes the other. and sometimes it would be really easy to "convert back", ex. you can really easily find a circle from a series of points placed equally around a common center (we should implement that in freecad..). and if you look at a cylinder in elevation in blender, it even renders the way we traditionally drew curved surfaces, with parallel lines closer to each other as the curvature grows :)
It's like with bitmap, with enough resolution, it ceases to be a problem
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by Moult on 5 Sep 2020
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@theoryshaw the radius value is implicitly stored in the mesh - the circle facet will always have a multiple of 4 vertices, this allows you to therefore always reliably re-derive the radius easily by measuring, even in its faceted form - it will give the correct radius / diameter no matter which vertice you pick.