I've been working on converting the vba version I had to C#, I'm getting there.
The winding method used by
http://softsurfer.com is far superior to the usual counting ray crossing method, and does work for selfintersecting polylines. Unfortunately it doesn't work for curves.
Although I have added some math that works fine for bumps, it's pretty expensive and I don't understand math well enough to make it leaner. Perhaps someone can help. I hope the actual code is not too offensive to those who know C#. I gotta say that I totally miss the point with enums.
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.Runtime;
using System.Collections;
using System;
using cad = Autodesk.AutoCAD.ApplicationServices.Application;
using Util;
namespace Getit
{
public class PtinPoly
{
////Uses http://softsurfer.com but also makes it work for curves
//07-16-07 CCP
[Flags]
public enum isInside
{Inside,Outside,Selfintersecting}
public static isInside PtInsidePoly(Point3d p, Polyline oPline)
{
//1) Use the winding count to see if the point is inside a straigth sided poly
//2) Then checks for arcs
Editor ed = cad.DocumentManager.MdiActiveDocument.Editor;
Point2d P1, P2;
double dBulge;
int Testbulge, wn = 0; //winding count
int Cnt = oPline.NumberOfVertices;
Point2dCollection PtS=new Point2dCollection();
for (int i = 0; i < Cnt; i++){
Point2d Pt = oPline.GetPoint2dAt(i);
PtS.Add(Pt);
}
PtS.Add(PtS[0]);
PtS.TrimToSize();
for (int i = 0; i < Cnt; i++){ //loop through all edges of the polygon
P1 = PtS[i];
P2 = PtS[i + 1];
if (P1.Y <= p.Y){ //start y <= P.y
if (P2.Y > p.Y){ //an upward crossing
if (MyMath.isLeft(P1, P2, p) > 0){ //P left of edge Cw
++wn; } //have a valid up intersect
}
}
else{ //start y > P.y (no test needed)
if (P2.Y <= p.Y){ //a downward crossing
if (MyMath.isLeft(P1, P2, p) < 0){ //P right of edge Cww
--wn; //have a valid down intersect
}
}
}
}
if ((oPline.IsOnlyLines)){ //Lines only
if (wn == 0){
return isInside.Outside;
}
else{
ed.WriteMessage("\nWinding={0}", wn);
return isInside.Inside;
}
}
//Now for the arcs
//if( wn = 0 ) //Point is inside verticies using straight lines
//if( bumps go out and the point is in one ) point is in the poly
//The opposite applies if( wn<>0)
if (SelfIntersectingCheck(oPline)){ //This is hardly necessary as it often gives the correct answer
ed.WriteMessage("\nThis poly is self intersecting.");
return isInside.Selfintersecting;
}
bool Cw = MyMath.IsClockwise(oPline);
for (int i = 0; i < Cnt; i++){
dBulge = oPline.GetBulgeAt(i);
if (dBulge == 0) goto skip; // continue
//Now we only have curves
Testbulge = Math.Sign(dBulge);
if (wn == 0) { Testbulge = -Testbulge; }
if (Cw){ //poly is clockwise
if (Testbulge < 0) goto skip; //inward bumps dont matter
}
else{ //poly is counterclockwise
if (Testbulge > 0) goto skip; //inward bumps dont matter
}
if (PtinSeg(p, PtS[i], PtS[i + 1], dBulge) == true){
if (wn == 0){
return isInside.Inside;
}
else{
return isInside.Outside;
}
}
skip: ;
}
if (wn != 0){
return isInside.Inside;
}
else { return isInside.Outside;
}
}
private static bool SelfIntersectingCheck(Polyline P)
{
try
{
DBObjectCollection curves = new DBObjectCollection();
curves.Add(P);
DBObjectCollection Rs = Region.CreateFromCurves(curves);
}
catch (System.Exception)
{
return true;
}
return false;
}
//07-16-07 CCP
public static bool PtinSeg(Point3d pt, Point2d p1, Point2d p2, double dBulge)
{
//Find the center of the arc
//Center is on the perp. biscector of p1,p2
//Check if length from center is > radius
//Check if pt
if (dBulge == 0) return false;
double PDist;
double m, mV, dLength;
double Y, X;
int iLeft;
double deltaX = p2.X - p1.X;
double deltaY = p2.Y - p1.Y;
if (Math.Abs(deltaX) < 1.0e-8) { deltaX = 0; }//Check for close to zero
if (Math.Abs(deltaY) < 1.0e-8) { deltaY = 0; }
double halfseg = 0.5 * Util.MyMath.Length(p1, p2);
double dRad = halfseg / Math.Sin(Math.Atan(dBulge) * 2);
double Dist = dRad - (dBulge * halfseg); //tan=opp/adj
if (deltaX > 0 && deltaY >= 0) { Dist = -Dist; }
if (deltaX < 0 && deltaY > 0) { Dist = -Dist; }
if (deltaY == 0){ //Line p1,p2 is horizontal
Y = p1.Y;
X = p1.X + 0.5 * deltaX;
Y = Y - Dist;
}
else if (deltaX == 0){ //Line p1,p2 is vertical
Y = p1.Y + 0.5 * deltaY;
X = p1.X;
if (deltaY < 0) Dist = -Dist;
X = X - Dist;
}
else{
m = deltaY / deltaX;
mV = -1 / m; //Invert slope for perpendicular bisector
X = p1.X + 0.5 * deltaX; //Find the midpoint
Y = p1.Y + 0.5 * deltaY;
//X = X1 + distance / dLength * DX
//proving for DeltaX=1 in slope direction
//slope=DeltaY / 1 => DeltaY=slope
dLength = Math.Sqrt((mV*mV) + 1);
X = X + (Dist / dLength) * 1;
Y = Y + (Dist / dLength) * mV;
}
Point3d CenPt = new Point3d(X, Y, 0);//To do Sort out 3d
//Quicktest
PDist = Util.MyMath.Length(pt, CenPt);
if (PDist > Math.Abs(dRad))
{ return false; }
else
{
iLeft = MyMath.isLeft(p1, p2, pt);
if (dBulge > 0){
if (iLeft == -1)
return true;
}
else{ //if (dBulge < 0)
if (iLeft == 1)
return true;
}
}
return false;
}
public bool BBCheck(Point3d P,Entity Ent){
Extents3d Ext=Ent.GeomExtents;
Point3d max=Ext.MaxPoint;
Point3d min=Ext.MinPoint;
if (P.X > max.X) {return false;}
if (P.X < min.X) {return false;}
if (P.Y > max.Y ) {return false;}
if (P.Y < min.Y ) {return false;}
return true;
}
public isInside PointinPoly(Point3d p, Polyline oPline)
{
if (BBCheck(p, oPline) == false){
return isInside.Outside;
}
return(PtInsidePoly(p, oPline));
}
[CommandMethod("PTP")]
public void CreateEmployee()
{
Document doc = cad.DocumentManager.MdiActiveDocument;
Editor ed = doc.Editor;
Database db = doc.Database;
PromptEntityResult res = ed.GetEntity("\nSelect the polyline: ");
PromptPointResult Pr = ed.GetPoint("\nPick a point: ");
Point3d P = Pr.Value;
if (res.Status != PromptStatus.OK) return;
if (Pr.Status != PromptStatus.OK) return;
using (Transaction tr = db.TransactionManager.StartTransaction()){
Polyline poly = tr.GetObject(res.ObjectId, OpenMode.ForRead, false) as Polyline;
if (poly == null) return;
ed.WriteMessage("\nIs clockwise={0}", MyMath.IsClockwise(poly));
isInside isP = PointinPoly(P, poly);
ed.WriteMessage("\nPoint is inside poly={0}", isP);
}
}
[CommandMethod("cw")]
public void iscw()
{
Document doc = cad.DocumentManager.MdiActiveDocument;
Editor ed = doc.Editor;
Database db = doc.Database;
PromptEntityResult res = ed.GetEntity("\nSelect the polyline: ");
DBObjectCollection curves=new DBObjectCollection();
if (res.Status != PromptStatus.OK) return;
Transaction tr = db.TransactionManager.StartTransaction();
try
{
Polyline poly = tr.GetObject(res.ObjectId, OpenMode.ForRead, false) as Polyline;
curves.Add(poly);
DBObjectCollection Rs = Region.CreateFromCurves(curves);
if (poly == null) return;
ed.WriteMessage("\nIs clockwise={0}", MyMath.IsClockwise(poly));
}
catch
{ed.WriteMessage("\nThe poly is selfcrossing.");}
finally{tr.Dispose();}
}
}
}and a couple of utilities
class MyMath
{
public const int Horizontal = 0;
public const int Vertical = 1;
public const int Sloped = 2;
public static double Abs(Double Num)
{
if (Math.Abs(Num) < 1.0e-8)
{
Num = 0;
return 0;
}
else
{
if (Num > 0)
{ return Num; }
else
{ return -Num; }
}
}
public static int isLeft(Point2d Startpoint, Point2d Endpoint, Point2d P)
{
double Ans = ((Endpoint.X - Startpoint.X) * (P.Y - Startpoint.Y)) -
((P.X - Startpoint.X) * (Endpoint.Y - Startpoint.Y));
if (Math.Abs(Ans) < 1.0e-8)
{ return 0; } //P is on the line
else
{
if (Ans > 0)
{ return 1; } //P is left of the line (CW)
else
{ return -1; } //P is right of the line (CCW)
}
}
public static int isLeft(Point2d Startpoint, Point2d Endpoint, Point3d P)
{
double Ans = (Endpoint.X - Startpoint.X) * (P.Y - Startpoint.Y) -
(P.X - Startpoint.X) * (Endpoint.Y - Startpoint.Y);
if (Math.Abs(Ans) < 1.0e-8)
{ return 0; } //P is on the line
else
{
if (Ans > 0)
{ return 1; } //P is left of the line (CW)
else
{ return -1; } //P is right of the line (CCW)
}
}
public static int isLeft(Point3d Startpoint, Point3d Endpoint, Point3d P)
{
double Ans = (Endpoint.X - Startpoint.X) * (P.Y - Startpoint.Y -
(P.X - Startpoint.X) * (Endpoint.Y - Startpoint.Y));
if (Math.Abs(Ans) < 1.0e-8)
{ return 0; } //P is on the line
else
{
if (Ans > 0)
{ return 1; } //P is left of the line (CW)
else
{ return -1; } //P is right of the line (CCW)
}
}
//Length
public static double Length(Point2d P1)
{ return Math.Sqrt((P1.X * P1.X) + (P1.Y * P1.Y)); }
public static double Length(Point2d P1, Point2d P2)
{
double dX = P2.X - P1.X;
double dY = P2.Y - P1.Y;
return Math.Sqrt((dX * dX) + (dY * dY));
}
public static double Length(Point3d P1)
{
return Math.Sqrt((P1.X * P1.X) + (P1.Y * P1.Y) + (P1.Z * P1.Z));
}
public static double Length(Point3d P1, Point3d P2)
{
double dX = P2.X - P1.X;
double dY = P2.Y - P1.Y;
double dZ = P2.Z - P1.Z;
return Math.Sqrt((dX * dX) + (dY * dY) + (dZ * dZ));
}
//http://softsurfer.com/Archive/algorithm_0101/algorithm_0101.htm#orientation2D_polygon()
public static bool IsClockwise(Polyline oPline)
{
// first find rightmost lowest vertex of the polygon
int rmin = 0;
int n = oPline.NumberOfVertices;
if (n == 2) { return false; }
Point2dCollection V = new Point2dCollection();
for(int i=0;i<n;i++)
{V.Add(oPline.GetPoint2dAt(i));}
V.Add (V[0]);
V.TrimToSize();
double xmin = V[0].X;
double ymin = V[0].Y;
for (int i = 1; i < n; i++)
{
if (V[i].Y > ymin)
continue;
if (V[i].Y == ymin)
{ // just as low
if (V[i].X < xmin) // and to left
continue;
}
rmin = i; // a new rightmost lowest vertex
xmin = V[i].X;
ymin = V[i].Y;
}
// test orientation at this rmin vertex
// ccw <=> the edge leaving is left of the entering edge
if (rmin == 0)
{
if (MyMath.isLeft( V[n - 1], V[1] , V[0])>0)
{
return true; }
}
else
{
if (MyMath.isLeft(V[rmin - 1], V[rmin + 1] , V[rmin]) > 0)
{
return true;}
}
//If we get to here it's false
return false;
}
public static bool isZero(double num)
{
//if( (Math.Abs(num) < 0.00000001)
if (num > -0.00000001)
{
if (num < 0.00000001)
{
num = 0;
return true;
}
}
return false;
}
public static bool Zero(double num)
{
if (Math.Abs(num) < 0.00000001)
{
num = 0;
return true;
}
return false;
}
So Vba is verbose ha?
