public static bool OnSegment(IntPoint start, IntPoint testPosition, IntPoint end)
{
if (start == end)
{
if (testPosition == start)
{
return(true);
}
return(false);
}
IntPoint segmentDelta = end - start;
long segmentLength = segmentDelta.Length();
IntPoint pointRelStart = testPosition - start;
long distanceFromStart = segmentDelta.Dot(pointRelStart) / segmentLength;
if (distanceFromStart >= 0 && distanceFromStart <= segmentLength)
{
IntPoint segmentDeltaLeft = segmentDelta.GetPerpendicularLeft();
long distanceFromStartLeft = segmentDeltaLeft.Dot(pointRelStart) / segmentLength;
if (distanceFromStartLeft == 0)
{
return(true);
}
}
return(false);
}
public static void MovePointInsideBoundary(this Polygons boundaryPolygons, IntPoint startPosition, out Tuple <int, int, IntPoint> polyPointPosition,
List <QuadTree <int> > edgeQuadTrees = null,
List <QuadTree <int> > pointQuadTrees = null)
{
Tuple <int, int, IntPoint> bestPolyPointPosition = new Tuple <int, int, IntPoint>(0, 0, startPosition);
if (boundaryPolygons.PointIsInside(startPosition, edgeQuadTrees, pointQuadTrees))
{
// already inside
polyPointPosition = null;
return;
}
long bestDist = long.MaxValue;
IntPoint bestMoveDelta = new IntPoint();
for (int polygonIndex = 0; polygonIndex < boundaryPolygons.Count; polygonIndex++)
{
var boundaryPolygon = boundaryPolygons[polygonIndex];
if (boundaryPolygon.Count < 3)
{
continue;
}
for (int pointIndex = 0; pointIndex < boundaryPolygon.Count; pointIndex++)
{
IntPoint segmentStart = boundaryPolygon[pointIndex];
IntPoint pointRelStart = startPosition - segmentStart;
long distFromStart = pointRelStart.Length();
if (distFromStart < bestDist)
{
bestDist = distFromStart;
bestPolyPointPosition = new Tuple <int, int, IntPoint>(polygonIndex, pointIndex, segmentStart);
}
IntPoint segmentEnd = boundaryPolygon[(pointIndex + 1) % boundaryPolygon.Count];
IntPoint segmentDelta = segmentEnd - segmentStart;
long segmentLength = segmentDelta.Length();
IntPoint segmentLeft = segmentDelta.GetPerpendicularLeft();
long segmentLeftLength = segmentLeft.Length();
long distanceFromStart = segmentDelta.Dot(pointRelStart) / segmentLength;
if (distanceFromStart >= 0 && distanceFromStart <= segmentDelta.Length())
{
long distToBoundarySegment = segmentLeft.Dot(pointRelStart) / segmentLeftLength;
if (Math.Abs(distToBoundarySegment) < bestDist)
{
IntPoint pointAlongCurrentSegment = startPosition;
if (distToBoundarySegment != 0)
{
pointAlongCurrentSegment = startPosition - segmentLeft * distToBoundarySegment / segmentLeftLength;
}
bestDist = Math.Abs(distToBoundarySegment);
bestPolyPointPosition = new Tuple <int, int, IntPoint>(polygonIndex, pointIndex, pointAlongCurrentSegment);
bestMoveDelta = segmentLeft;
}
}
segmentStart = segmentEnd;
}
}
polyPointPosition = bestPolyPointPosition;
}