From 206933a2f25c29a1c4b3cb9ed79122c992c75a61 Mon Sep 17 00:00:00 2001
From: Thomas Krijnen <t.krijnen@gmail.com>
Date: Thu, 15 Jun 2023 16:18:48 +0200
Subject: [PATCH] #2819 Handle periodic bspline curves in serialization

---
 src/ifcgeom/Serialization.cpp | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/ifcgeom/Serialization.cpp b/src/ifcgeom/Serialization.cpp
index 7a4f346528..8eabd1732b 100644
--- a/src/ifcgeom/Serialization.cpp
+++ b/src/ifcgeom/Serialization.cpp
@@ -18,6 +18,8 @@
 
 #include "IfcGeom.h"
 
+#include <numeric>
+
 template <typename T, typename U>
 int convert_to_ifc(const T& t, U*& u, bool /*advanced*/) {
 	std::vector<double> coords(3);
@@ -220,6 +222,15 @@ int convert_to_ifc(const Handle_Geom_Curve& c, IfcSchema::IfcCurve*& curve, bool
 			}
 		}
 
+		if (bspline->IsPeriodic() && points->size()) {
+			points->push(*points->begin());
+			weights.push_back(weights[0]);
+			auto sum = std::accumulate(mults.begin(), mults.end(), 0);
+			auto d = sum - (bspline->Degree() + (int)points->size() + 1);
+			(*mults.begin()) -= d / 2;
+			(*mults.rbegin()) -= d / 2;
+		}
+
 		if (rational) {
 			curve = new IfcSchema::IfcRationalBSplineCurveWithKnots(
 				bspline->Degree(),