/// <summary>
/// Accurate Clip Polygon with Line
/// </summary>
/// <param name="polygon"></param>
/// <param name="line"></param>
/// <param name="resultFeatureSet"></param>
/// <returns></returns>
public static bool Accurate_ClipPolygonWithLine(
ref IFeature polygon, ref IFeature line, ref IFeatureSet resultFeatureSet)
{
if (polygon != null && line != null)
{
bool boundsIntersect = line.Crosses(polygon);
if (boundsIntersect == false)
{
return false;
}
// find if all of the line is inside, outside, or part in and out of polygon
// line might intersect polygon mutliple times
int numPoints = line.NumPoints;
bool[] ptsInside = new bool[numPoints];
int numInside = 0;
int numOutside = 0;
int numParts = polygon.NumPoints;
if (numParts == 0)
{
numParts = 1;
}
Coordinate[][] polyVertArray = new Coordinate[numParts][];
ConvertPolyToVertexArray(ref polygon, ref polyVertArray);
// check each point in the line to see if the entire line is either
// inside of the polygon or outside of it (we know it's inside polygon bounding box).
for (int i = 0; i <= numPoints - 1; i++)
{
Point currPt = new Point(line.Coordinates[i]);
if (polygon.Covers(currPt))
{
ptsInside[i] = true;
numInside += 1;
}
else
{
ptsInside[i] = false;
numOutside += 1;
}
}
if (numInside == numPoints)
{
// case: all points are inside polygon - check for possible intersections
if (ProcessAllInside(ref line, ref polygon, ref resultFeatureSet) == false)
{
return false;
}
}
else if (numOutside == numPoints)
{
// case: all points are outside of the polygon - check for possible intersections
if (ProcessAllOutside(ref line, ref polygon, ref resultFeatureSet) == false)
{
return false;
}
}
else
{
// case: part of line is inside and part is outside - find inside segments.
if (ProcessPartInAndOut(ref ptsInside, ref line, ref polygon, ref resultFeatureSet) == false)
{
return false;
}
}
}
else
{
return false;
}
return true;
}
