public static IEnumerable <Line> ToLines(this Polygon2d _polygon)
{
List <Line> lines = new List <Line>();
foreach (var seg in _polygon.SegmentItr())
{
lines.Add(seg.ToLine());
}
return(lines);
}
public static bool BiContains(this Polygon2d poly, Segment2d seg)
{
foreach (Segment2d thisSeg in poly.SegmentItr())
{
if (thisSeg.BiEquals(seg))
{
return(true);
}
}
return(false);
}
public static bool InPolygon2d(this Vector2d vector2d, Polygon2d polygon2d)
{
//【】判断点是否落在多边形线段上
foreach (Segment2d segment2d in polygon2d.SegmentItr())
{
double distance = segment2d.DistanceSquared(vector2d);
if (distance.EqualZreo())
{
return(false);
}
}
return(polygon2d.Contains(vector2d));
}
/// <summary>
/// 直线与线圈相交
/// </summary>
/// <returns></returns>
public static IEnumerable <Vector2d> IntrLine2Polygon(this Line2d segment2d_p0, Polygon2d regionPolygon2d)
{
IEnumerable <Segment2d> segment2ds = regionPolygon2d.SegmentItr();
IntrLine2Segment2 intrLine2Segment2 = new IntrLine2Segment2(segment2d_p0, segment2ds.First());
foreach (var item in segment2ds)
{
intrLine2Segment2.Segment = item;
intrLine2Segment2.Compute();
if (intrLine2Segment2.Quantity == 1)
{
yield return(intrLine2Segment2.Point);
}
}
}
public static CurveLoop ToCurveLoop(this Polygon2d _polygon2d)
{
_polygon2d = _polygon2d.DelDuplicate();
List <Line> lines = new List <Line>();
foreach (var seg in _polygon2d.SegmentItr())
{
lines.Add(seg.ToLine());
}
CurveLoop curves = new CurveLoop();
foreach (Line line in lines)
{
Curve _c = line as Curve;
curves.Append(_c);
}
return(curves);
}
/// <summary>
/// 线圈是否为直角梯形
/// </summary>
/// <returns></returns>
public static bool IsTrapezoid_RightAngle(this Polygon2d polygon2d)
{
int count = polygon2d.VertexCount;
if (count != 4)
{
return(false);
}
int calAngleCounr = 0;
for (int i = 0; i < polygon2d.VertexCount; i++)
{
if (polygon2d.OpeningAngleDeg(i).EqualPrecision(90))
{
calAngleCounr += 1;
}
}
if (calAngleCounr != 2)
{
return(false);
}
IEnumerable <Segment2d> segment2ds = polygon2d.SegmentItr();
int segmntCount = segment2ds.Count();
for (int i = 0; i < segmntCount; i++)
{
for (int j = 0; j < segmntCount; j++)
{
if (i <= j)
{
continue;
}
Segment2d segment2d01 = segment2ds.ElementAt(i);
Segment2d segment2d02 = segment2ds.ElementAt(j);
if (segment2d01.Direction.Dot(segment2d02.Direction).EqualPrecision(-1))
{
return(true);
}
}
}
return(false);
}
/// <summary>
/// 线圈是否为梯形 ——原则：四个角点，一对平行边
/// </summary>
/// <returns></returns>
public static bool IsTrapezoid(this Polygon2d polygon2d)
{
int count = polygon2d.VertexCount;
if (count != 4)
{
return(false);
}
IEnumerable <Segment2d> segment2ds = polygon2d.SegmentItr();
int segmntCount = segment2ds.Count();
int pedCount = 0;
for (int i = 0; i < segmntCount; i++)
{
for (int j = 0; j < segmntCount; j++)
{
if (i <= j)
{
continue;
}
Segment2d segment2d01 = segment2ds.ElementAt(i);
Segment2d segment2d02 = segment2ds.ElementAt(j);
if (segment2d01.Direction.Dot(segment2d02.Direction).EqualPrecision(-1))
{
if (segment2d01.Length > segment2d02.Length)
{
pedCount += 1;
}
}
}
}
if (pedCount == 1)
{
return(true);
}
return(false);
}
/// <summary>
/// Trim / split a segment by a polygon.
/// </summary>
/// <param name="_type">0 = inside; 1 = outside ; 2 = both sides</param>
public static List <Segment2d> Trim(this Polygon2d _polygon, Segment2d _seg, int _type)
{
var list = new List <Segment2d>();
//find intersections
List <KeyValuePair <double, Vector2d> > intPs = new List <KeyValuePair <double, Vector2d> >();
foreach (var edge in _polygon.SegmentItr())
{
var segIntr = new IntrSegment2Segment2(_seg, edge);
bool b = segIntr.Find();
if (b)
{
intPs.Add(new KeyValuePair <double, Vector2d>(segIntr.Parameter0, segIntr.Point0));
}
}
//if no intersection
if (intPs.Count == 0)
{
if (_type == 1)
{
//return empty list
}
else
{
//check if segment is contained inside polygon
if (_polygon.Contains(_seg))
{
list.Add(_seg);
}
}
return(list);
}
//sort intersection points by position
var sortedIntPs = intPs.OrderBy(x => x.Key).Select(x => x.Value).ToList();
//get two list of segments from intersections
var list0 = new List <Segment2d>();
var list1 = new List <Segment2d>()
{
new Segment2d(_seg.P0, sortedIntPs[0])
};
for (int i = 1; i < sortedIntPs.Count; i += 2)
{
Vector2d p0, p1, p2;
p0 = sortedIntPs[i - 1];
p1 = sortedIntPs[i];
list0.Add(new Segment2d(p0, p1));
if (i + 1 < sortedIntPs.Count)
{
p2 = sortedIntPs[i + 1];
list1.Add(new Segment2d(p1, p2));
}
}
//use even/odd of intr num to decide the last segment
var last = new Segment2d(sortedIntPs.Last(), _seg.P1);
if (sortedIntPs.Count % 2 == 0)
{
list1.Add(last);
}
else
{
list0.Add(last);
}
//check starting point inside or outside
bool startInside = _polygon.Contains(_seg.P0);
//return coresponding list of segments
if (_type == 0)
{
return(startInside ? list1 : list0);
}
else if (_type == 1)
{
return(startInside ? list0 : list1);
}
else
{
list.AddRange(list0);
list.AddRange(list1);
return(list);
}
}