From 0e6962c311541695a62795ee2ffa6cab62c13881 Mon Sep 17 00:00:00 2001
From: Thomas Krijnen <t.krijnen@gmail.com>
Date: Sat, 7 Aug 2021 11:23:41 +0200
Subject: [PATCH] further optional type changes

---
 src/ifcgeom/IfcGeomShapes.cpp | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/ifcgeom/IfcGeomShapes.cpp b/src/ifcgeom/IfcGeomShapes.cpp
index f7c0a05693..b44f830ffa 100644
--- a/src/ifcgeom/IfcGeomShapes.cpp
+++ b/src/ifcgeom/IfcGeomShapes.cpp
@@ -1531,8 +1531,18 @@ bool IfcGeom::Kernel::convert(const IfcSchema::IfcSweptDiskSolid* l, TopoDS_Shap
 	if (!convert_wire(l->Directrix(), wire)) {
 		return false;
 	}
+	
+	// Start- EndParam became optional in IFC4
+#ifdef SCHEMA_IfcSweptDiskSolid_StartParam_IS_OPTIONAL
+	auto sp = l->StartParam();
+	auto ep = l->EndParam();
+#else
+	boost::optional<double> sp, ep;
+	sp = l->StartParam();
+	ep = l->EndParam();
+#endif
 
-	if (count(wire, TopAbs_EDGE) == 1) {
+	if (count(wire, TopAbs_EDGE) == 1 && sp && ep) {
 		TopoDS_Vertex v0, v1;
 		TopExp::Vertices(wire, v0, v1);
 		if (v0.IsSame(v1)) {
@@ -1543,7 +1553,7 @@ bool IfcGeom::Kernel::convert(const IfcSchema::IfcSweptDiskSolid* l, TopoDS_Shap
 			if ((crv->DynamicType() == STANDARD_TYPE(Geom_Circle)) ||
 				(crv->DynamicType() == STANDARD_TYPE(Geom_Ellipse))) 
 			{
-				BRepBuilderAPI_MakeEdge me(crv, l->StartParam(), l->EndParam());
+				BRepBuilderAPI_MakeEdge me(crv, *sp, *ep);
 				if (me.IsDone()) {
 					auto e2 = me.Edge();
 					BRep_Builder B;