public static Polygon MakeCloseSegmentsMergable(this Polygon polygonToSplit, Polygon pointsToSplitOn, long distanceNeedingAdd, bool pathIsClosed = true)
{
List <Segment> segments = Segment.ConvertToSegments(polygonToSplit, pathIsClosed);
var touchingEnumerator = new PolygonEdgeIterator(pointsToSplitOn, distanceNeedingAdd);
// for every segment
for (int segmentIndex = segments.Count - 1; segmentIndex >= 0; segmentIndex--)
{
List <Segment> newSegments = segments[segmentIndex].GetSplitSegmentForVertecies(touchingEnumerator);
if (newSegments?.Count > 0)
{
// remove the old segment
segments.RemoveAt(segmentIndex);
// add the new ones
segments.InsertRange(segmentIndex, newSegments);
}
}
var segmentedPolygon = new Polygon(segments.Count);
foreach (var segment in segments)
{
segmentedPolygon.Add(segment.Start);
}
if (!pathIsClosed && segments.Count > 0)
{
// add the last point
segmentedPolygon.Add(segments[segments.Count - 1].End);
}
return(segmentedPolygon);
}
public static Intersection FindIntersection(this Polygon polygon, IntPoint start, IntPoint end, QuadTree <int> edgeQuadTree = null)
{
Intersection bestIntersection = Intersection.None;
IntPoint segmentDelta = end - start;
var edgeIterator = new PolygonEdgeIterator(polygon, 1, edgeQuadTree);
foreach (var i in edgeIterator.GetTouching(new Quad(start, end)))
{
IntPoint edgeStart = polygon[i];
// if we share a vertex we cannot be crossing the line
IntPoint edgeEnd = polygon[(i + 1) % polygon.Count];
if (start == edgeStart || start == edgeEnd || end == edgeStart || end == edgeEnd ||
start == polygon[i] || end == polygon[i])
{
bestIntersection = Intersection.Colinear;
}
else
{
var result = GetIntersection(start, end, edgeStart, edgeEnd);
if (result == Intersection.Intersect)
{
return(Intersection.Intersect);
}
else if (result == Intersection.Colinear)
{
bestIntersection = Intersection.Colinear;
}
}
}
return(bestIntersection);
}
public static IEnumerable <Tuple <int, IntPoint> > FindCrossingPoints(this Polygon polygon, IntPoint start, IntPoint end, QuadTree <int> edgeQuadTree = null)
{
IntPoint segmentDelta = end - start;
long segmentLength = segmentDelta.Length();
var edgeIterator = new PolygonEdgeIterator(polygon, 1, edgeQuadTree);
foreach (var i in edgeIterator.GetTouching(new Quad(start, end)))
{
IntPoint edgeStart = polygon[i];
IntPoint edgeEnd = polygon[(i + 1) % polygon.Count];
IntPoint intersection = new IntPoint();
if (OnSegment(edgeStart, start, edgeEnd))
{
yield return(new Tuple <int, IntPoint>(i, start));
}
else if (OnSegment(edgeStart, end, edgeEnd))
{
yield return(new Tuple <int, IntPoint>(i, end));
}
else if (DoIntersect(start, end, edgeStart, edgeEnd) &&
CalcIntersection(start, end, edgeStart, edgeEnd, out intersection))
{
IntPoint pointRelStart = intersection - start;
yield return(new Tuple <int, IntPoint>(i, intersection));
}
}
}
public static bool TouchingEdge(this Polygon polygon, IntPoint testPosition, QuadTree <int> edgeQuadTree = null)
{
var edgeIterator = new PolygonEdgeIterator(polygon, 1, edgeQuadTree);
foreach (var i in edgeIterator.GetTouching(new Quad(testPosition)))
{
IntPoint edgeStart = polygon[i];
IntPoint edgeEnd = polygon[(i + 1) % polygon.Count];
if (OnSegment(edgeStart, testPosition, edgeEnd))
{
return(true);
}
}
return(false);
}
public static IEnumerable <(int pointIndex, IntPoint position)> FindCrossingPoints(this Polygon polygon, IntPoint start, IntPoint end, QuadTree <int> edgeQuadTree = null)
{
var edgeIterator = new PolygonEdgeIterator(polygon, 1, edgeQuadTree);
foreach (var i in edgeIterator.GetTouching(new Quad(start, end)))
{
IntPoint edgeStart = polygon[i];
IntPoint edgeEnd = polygon[(i + 1) % polygon.Count];
if (OnSegment(edgeStart, start, edgeEnd))
{
yield return(i, start);
}
else if (OnSegment(edgeStart, end, edgeEnd))
{
yield return(i, end);
}
else if (DoIntersect(start, end, edgeStart, edgeEnd) &&
CalcIntersection(start, end, edgeStart, edgeEnd, out IntPoint intersection))
{
yield return(i, intersection);
}
}
}
public List <Segment> GetSplitSegmentForVertecies(PolygonEdgeIterator touchingEnumerator)
{
IntPoint start2D = new IntPoint(Start)
{
Z = 0
};
IntPoint end2D = new IntPoint(End)
{
Z = 0
};
SortedList <long, IntPoint> requiredSplits2D = new SortedList <long, IntPoint>();
// get some data we will need for the operations
IntPoint direction = (end2D - start2D);
long length = direction.Length();
long lengthSquared = length * length;
IntPoint rightDirection = direction.GetPerpendicularRightXY();
long maxDistanceNormalized = touchingEnumerator.OverlapAmount * length;
// for every vertex
foreach (int touchingPoint in touchingEnumerator.GetTouching(new Quad(this.Left, this.Bottom, this.Right, this.Top)))
//for (int splintIndex = 0; splintIndex < splitPoints.Count; splintIndex++)
{
IntPoint vertex = new IntPoint(touchingEnumerator.SourcePoints[touchingPoint])
{
Z = 0
} -start2D;
// if the vertex is close enough to the segment
long dotProduct = rightDirection.Dot(vertex);
if (Math.Abs(dotProduct) < maxDistanceNormalized)
{
long dotProduct2 = direction.Dot(vertex);
if (dotProduct2 > 0 && dotProduct2 < lengthSquared)
{
long distance = dotProduct2 / length;
// don't add if there is already a point at this position
if (!requiredSplits2D.ContainsKey(distance))
{
// we are close enough to the line split it
requiredSplits2D.Add(distance, start2D + direction * distance / length);
}
}
}
}
if (requiredSplits2D.Count > 0)
{
// add in the start and end
if (!requiredSplits2D.ContainsKey(0))
{
requiredSplits2D.Add(0, start2D);
}
if (!requiredSplits2D.ContainsKey(length))
{
requiredSplits2D.Add(length, end2D);
}
// convert to a segment list
List <Segment> newSegments = Segment.ConvertPathToSegments(requiredSplits2D.Values, Start.Z, false);
// return them;
return(newSegments);
}
return(null);
}
