判断点是否在封闭多段线内【转载+优化】
一、使用多重多边形。使用函数AppendLoopFromBoundary(pline, true, tolerance)传入多段线范围线和容差创建多重多边形，然后根据函数IsPointInsideMPolygon((point, tolerance). Count返回值是否为1来判断是否在多段线内部。二、使用Region和Brep，几乎所有的实体都适用于Region，通过Region.CreateFromCurves(curves)来创建Region，然后传入到Brep中，利用GetPointContainment(point, out result)返回的BrepEntity来判断是否是
Autodesk..BoundaryRepresentation.Face，如果是，则最终为多段线内。
当然这里的解释表现得抽象了些，大家可以通过阅读代码来了解细节方面流程。值得注意的是在使用上面的函数时，必须导入acdbmgdbrep、AcMPolygonMGD两个dll动态链接库。可以说MPolygon具有一定的拓扑运算能力，可以弥补AutoCAD在几何拓扑运算方面的小小缺陷。当然了更多MPolygon有待进一步研究。
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版权声明：本文为CSDN博主「yGIS」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.BoundaryRepresentation;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.Runtime;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace IsInPolyline
{
public class Class1
{
public static void test()
{
Document doc = Application.DocumentManager.MdiActiveDocument;
Database db = doc.Database;
Editor ed = doc.Editor;
PromptEntityOptions peo = new PromptEntityOptions("\n选择一条多段线: ");
peo.SetRejectMessage("Only a polyline !");
peo.AddAllowedClass(typeof(Polyline), true);
PromptEntityResult per = ed.GetEntity(peo);
if (per.Status != PromptStatus.OK)
return;
using (Transaction tr = db.TransactionManager.StartOpenCloseTransaction())
{
Polyline pline = (Polyline)tr.GetObject(per.ObjectId, OpenMode.ForRead);
PromptPointOptions ppo = new PromptPointOptions("\n拾取一个点 : ");
ppo.AllowNone = true;
while (true)
{
PromptPointResult ppr = ed.GetPoint(ppo);
if (ppr.Status != PromptStatus.OK)
break;
Application.ShowAlertDialog(
pline.IsPointInside(ppr.Value) ? "Inside" : "Outside");
}
}
}
public void test2() {
Document doc = Application.DocumentManager.MdiActiveDocument;
Database db = doc.Database;
Editor ed = doc.Editor;
PromptEntityOptions peo = new PromptEntityOptions("\n选择一条多段线: ");
peo.SetRejectMessage("Only a polyline !");
peo.AddAllowedClass(typeof(Polyline), true);
PromptEntityResult per = ed.GetEntity(peo);
if (per.Status != PromptStatus.OK)
return;
using (Transaction tr = db.TransactionManager.StartOpenCloseTransaction())
{
Polyline pline = (Polyline)tr.GetObject(per.ObjectId, OpenMode.ForRead);
if (!pline.Closed)
{
ed.WriteMessage("\n多段线必须为闭合");
return;
}
DBObjectCollection curves = new DBObjectCollection();
curves.Add(pline);
try
{
using (DBObjectCollection regions = Region.CreateFromCurves(curves))
using (Region region = (Region)regions)
{
PromptPointOptions ppo = new PromptPointOptions("\nPick a point : ");
ppo.AllowNone = true;
while (true)
{
PromptPointResult ppr = ed.GetPoint(ppo);
if (ppr.Status != PromptStatus.OK)
break;
Application.ShowAlertDialog(
GetPointContainment(region, ppr.Value).ToString());
}
}
}
catch (System.Exception exn)
{
ed.WriteMessage("\nError: " + exn.Message);
}
}
}
private PointContainment GetPointContainment(Region region, Point3d point)
{
PointContainment result = PointContainment.Outside;
using (Brep brep = new Brep(region))
{
if (brep != null)
{
using (BrepEntity ent = brep.GetPointContainment(point, out result))
{
if (ent is Autodesk.AutoCAD.BoundaryRepresentation.Face)
{
result = PointContainment.Inside;
}
}
}
}
return result;
}
}
}以上是原作者的代码。但是方法一缺少了重要的pline.IsPointInside(pt)，以下为自己东拼西凑的：IsPointInside(this Polyline pline, Point3d pt)
public static bool IsPointInside(this Polyline pline, Point3d pt)
{
bool str = true;
Document doc = Application.DocumentManager.MdiActiveDocument;
Database db = doc.Database;
Editor ed = doc.Editor;
using (var tr = db.TransactionManager.StartTransaction())
{
var btr = (BlockTableRecord)tr.GetObject(db.CurrentSpaceId, OpenMode.ForWrite);
var mPolygon = new MPolygon();
btr.AppendEntity(mPolygon);
tr.AddNewlyCreatedDBObject(mPolygon, true);
mPolygon.UpgradeOpen();
if (pline is Polyline)
mPolygon.AppendLoopFromBoundary((Polyline)pline, true, 1E-12);
mPolygon.ColorIndex = 1;
mPolygon.DowngradeOpen();
var jj = mPolygon.IsPointInsideMPolygon(pt, 1E-12).Count;
if (jj != 1)
{
str = false;
}
//tr.Commit();
}
return str;
}
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