public List <Vector2D> FindIntersections(Polygon2d o)
{
List <Vector2D> v = new List <Vector2D>();
if (!this.GetBounds().Intersects(o.GetBounds()))
{
return(v);
}
foreach (Segment2d seg in SegmentItr())
{
foreach (Segment2d oseg in o.SegmentItr())
{
IntrSegment2Segment2 intr = new IntrSegment2Segment2(seg, oseg);
if (intr.Find())
{
v.Add(intr.Point0);
if (intr.Quantity == 2)
{
v.Add(intr.Point1);
}
break;
}
}
}
return(v);
}
/// <summary>
/// Find any segment in set that intersects input segment.
/// Returns intersection test, and index of segment
/// </summary>
public IntrSegment2Segment2 FindAnyIntersection(Segment2d seg, out int iSegment)
{
int N = Segments.Count;
for (iSegment = 0; iSegment < N; ++iSegment)
{
IntrSegment2Segment2 intr = new IntrSegment2Segment2(seg, Segments[iSegment]);
if (intr.Find())
{
return(intr);
}
}
return(null);
}
public bool Intersects(Polygon2d o)
{
if (!this.GetBounds().Intersects(o.GetBounds()))
{
return(false);
}
foreach (Segment2d seg in SegmentItr())
{
foreach (Segment2d oseg in o.SegmentItr())
{
IntrSegment2Segment2 intr = new IntrSegment2Segment2(seg, oseg);
if (intr.Find())
{
return(true);
}
}
}
return(false);
}
public void FindAllIntersections(Segment2d seg, List <double> segmentTs, List <int> indices = null, List <IntrSegment2Segment2> tests = null, bool bOnlySimple = true)
{
int N = Segments.Count;
for (int i = 0; i < N; ++i)
{
// want to make sure we do not miss any hits, even if it means
// we get duplicates...
IntrSegment2Segment2 intr = new IntrSegment2Segment2(seg, Segments[i])
{
IntervalThreshold = math.MathUtil.ZeroTolerance
};
if (intr.Find())
{
if (bOnlySimple && intr.IsSimpleIntersection == false)
{
continue;
}
if (tests != null)
{
tests.Add(intr);
}
if (indices != null)
{
indices.Add(i);
}
if (segmentTs != null)
{
segmentTs.Add(intr.Parameter0);
if (!intr.IsSimpleIntersection)
{
segmentTs.Add(intr.Parameter1);
}
}
}
}
}
/// <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);
}
}