在OpenCASCADE中生成WIRE时要求添加到WIRE中的边EDGE是有顺序要求的。当给定的边没有按顺序添加到WIRE之前，需要自己将EDGE按顺序处理。OpenCASCADE中也提供了对EDGE按顺序进行排序的功能，方便WIRE的生成。
在模型检查模块TKShHealing中，OpenCASCADE提供了类ShapeAnalysis_WireOrder用来将用于生成WIRE的一系列EDGE进行排序。这个类的实现原理是根据EDGE的起点、终点坐标来进行连接，生成顺序。
/*
The MIT License (MIT)
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Copyright(C) 2018 Shing Liu(eryar@163.com)
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#include <vector>
#include <gp_Pnt.hxx>
#include <gp_Circ.hxx>
#include <TopTools_ListOfShape.hxx>
#include <BRep_Tool.hxx>
#include <BRepTools.hxx>
#include <BRepBuilderAPI_MakeEdge.hxx>
#include <BRepBuilderAPI_MakeWire.hxx>
#include <ShapeAnalysis_Edge.hxx>
#include <ShapeAnalysis_WireOrder.hxx>
#pragma comment(lib, "TKernel.lib")
#pragma comment(lib, "TKMath.lib")
#pragma comment(lib, "TKG2d.lib")
#pragma comment(lib, "TKG3d.lib")
#pragma comment(lib, "TKGeomBase.lib")
#pragma comment(lib, "TKGeomAlgo.lib")
#pragma comment(lib, "TKBRep.lib")
#pragma comment(lib, "TKTopAlgo.lib")
#pragma comment(lib, "TKShHealing.lib")
void test(void)
{
std::vector<TopoDS_Edge> anEdges;
// 5 Segment edges.
BRepBuilderAPI_MakeEdge anEdgeMaker1(
gp_Pnt(-1650.0, 2857.88383249, 0.0),
gp_Pnt(-750.0, 1299.03810568, 0.0));
BRepBuilderAPI_MakeEdge anEdgeMaker2(
gp_Pnt(1299.03810568, 750.0, 0.0),
gp_Pnt(2857.88383249, 1650.0, 0.0));
BRepBuilderAPI_MakeEdge anEdgeMaker3(
gp_Pnt(2857.88383249, 1650.0, 0.0),
gp_Pnt(8000.0, 1650.0, 0.0));
BRepBuilderAPI_MakeEdge anEdgeMaker4(
gp_Pnt(8000.0, 1650.0, 0.0),
gp_Pnt(8000.0, -3300.0, 0.0));
BRepBuilderAPI_MakeEdge anEdgeMaker5(
gp_Pnt(8000.0, -3300.0, 0.0),
gp_Pnt(0.0, -3300.0, 0.0));
anEdges.push_back(anEdgeMaker1.Edge());
anEdges.push_back(anEdgeMaker2.Edge());
anEdges.push_back(anEdgeMaker3.Edge());
anEdges.push_back(anEdgeMaker4.Edge());
anEdges.push_back(anEdgeMaker5.Edge());
// 2 Arc edges.
gp_Circ aCircle1(gp::XOY(), 1500.0);
gp_Circ aCircle2(gp::XOY(), 3300.0);
BRepBuilderAPI_MakeEdge anEdgeMaker6(aCircle1,
gp_Pnt(-750.0, 1299.03810568, 0.0),
gp_Pnt(1299.03810568, 750.0, 0.0));
BRepBuilderAPI_MakeEdge anEdgeMaker7(aCircle2,
gp_Pnt(-1650.0, 2857.88383249, 0.0),
gp_Pnt(0.0, -3300.0, 0.0));
anEdges.push_back(anEdgeMaker6.Edge());
anEdges.push_back(anEdgeMaker7.Edge());
// Get edges order for the wire.
ShapeAnalysis_Edge anEdgeAnalyser;
ShapeAnalysis_WireOrder aWireOrder;
for (std::vector<TopoDS_Edge>::const_iterator i = anEdges.begin();
i != anEdges.end(); ++i)
{
TopoDS_Vertex aVf = anEdgeAnalyser.FirstVertex(*i);
TopoDS_Vertex aVl = anEdgeAnalyser.LastVertex(*i);
gp_Pnt aPf = BRep_Tool::Pnt(aVf);
gp_Pnt aPl = BRep_Tool::Pnt(aVl);
aWireOrder.Add(aPf.XYZ(), aPl.XYZ());
}
//
TopTools_ListOfShape aOrderedEdges;
for (Standard_Integer e = 1; e <= aWireOrder.NbEdges(); ++e)
{
const TopoDS_Edge& anEdge = anEdges.at(e - 1);
aOrderedEdges.Append(anEdge);
}
BRepBuilderAPI_MakeWire aWireMaker;
aWireMaker.Add(aOrderedEdges);
if (aWireMaker.IsDone())
{
BRepTools::Write(aWireMaker.Shape(), "d:/wire.brep");
}
}
int main(int argc, char* argv[])
{
test();
return 0;
}
程序先添加5条线段到EDGE数组，再添加两个圆弧到EDGE数组。再使用类ShapeAnalysis_WireOrder来对EDGE数组进行排序，将排序后的EDGE数组去生成WIRE。如果生成WIRE成功，会在D盘得到一个wire.brep文件。在Draw中加载后显示如下图所示：
OpenCASCADE中生成WIRE时对添加的EDGE是有顺序的要求。如何对散乱的EDGE进行排序以达到生成WIRE的要求呢？OpenCASCADE在TKShHealing模块中提供了对EDGE排序的功能。