/// <summary>
/// Determines if a point in inside or outside a polygon. Inside
/// includes on the edge for this method.
/// Works for both convex and concave polygons (Winding number test)
/// </summary>
/// <param name="x">x-coordinate for the point</param>
/// <param name="y">y-coordiante for the point</param>
/// <param name="polygon">Polygon</param>
/// <returns>
/// <p>true: If the point is inside the polygon</p>
/// <p>false: If the point is outside the polygon.</p>
/// </returns>
protected static bool IsPointInPolygonOrOnEdge(double x, double y, XYPolygon polygon)
{
bool result = IsPointInPolygon(x, y, polygon);
if (result)
{
return(result);
}
else
{
int iLine = 0;
while ((!result) && (iLine < polygon.Points.Count))
{
var line = polygon.GetLine(iLine);
result = IsPointInLine(x, y, line);
iLine++;
}
}
return(result);
}
[Test] public void GetLine()
{
// -- Triangle --
XYPolygon xypolygon = new XYPolygon();
xypolygon.Points.Add(new XYPoint(1,2));
xypolygon.Points.Add(new XYPoint(4,3));
xypolygon.Points.Add(new XYPoint(2,5));
Assert.AreEqual(new XYLine(1,2,4,3),xypolygon.GetLine(0));
Assert.AreEqual(new XYLine(4,3,2,5),xypolygon.GetLine(1));
Assert.AreEqual(new XYLine(2,5,1,2),xypolygon.GetLine(2));
// -- concave polygon --
XYPolygon xypolygon4 = new XYPolygon();
xypolygon4.Points.Add(new XYPoint(1,1));
xypolygon4.Points.Add(new XYPoint(9,1));
xypolygon4.Points.Add(new XYPoint(5,5));
xypolygon4.Points.Add(new XYPoint(5,3));
xypolygon4.Points.Add(new XYPoint(3,3));
xypolygon4.Points.Add(new XYPoint(3,8));
xypolygon4.Points.Add(new XYPoint(9,8));
xypolygon4.Points.Add(new XYPoint(9,11));
xypolygon4.Points.Add(new XYPoint(1,11));
Assert.AreEqual(new XYLine(1, 1, 9, 1),xypolygon4.GetLine(0));
Assert.AreEqual(new XYLine(9, 1, 5, 5),xypolygon4.GetLine(1));
Assert.AreEqual(new XYLine(5, 5, 5, 3),xypolygon4.GetLine(2));
Assert.AreEqual(new XYLine(5, 3, 3, 3),xypolygon4.GetLine(3));
Assert.AreEqual(new XYLine(3, 3, 3, 8),xypolygon4.GetLine(4));
Assert.AreEqual(new XYLine(3, 8, 9, 8),xypolygon4.GetLine(5));
Assert.AreEqual(new XYLine(9, 8, 9, 11),xypolygon4.GetLine(6));
Assert.AreEqual(new XYLine(9,11, 1 ,11),xypolygon4.GetLine(7));
Assert.AreEqual(new XYLine(1,11, 1 , 1),xypolygon4.GetLine(8));
}
/// <summary>
/// The method calculates the intersection points of triangle a and b both
/// of type XYPolygon.
/// </summary>
/// <param name="triangleA">triangle. The search is started along triangleA.</param>
/// <param name="triangleB">triangle. Intersection with this triangle are sought.</param>
/// <param name="p">Starting point for the search. p must be part of triangleA.</param>
/// <param name="i">on input: End index for the first line segment of triangleA in the search.
/// on output: End index for the last intersected line segment in triangleA.</param>
/// <param name="j">on input: -1 if vertices before intersection is not to be added to list.
/// on output: End index for last intersected line segment of triangleB.</param>
/// <param name="intersectionPolygon">polygon eventuallu describing the
/// intersection area between triangleA and triangleB</param>
/// <returns>
/// The p, i, j and intersectionPolygon are called by reference and modified in the method.
/// </returns>
private static void Intersect(XYPolygon triangleA, XYPolygon triangleB,
ref XYPoint p, ref int i, ref int j,
ref XYPolygon intersectionPolygon)
{
XYLine lineA;
XYLine lineB;
int im1 = Decrease(i, 2); // "i-1"
int count1 = 0;
bool found = false;
while ((count1 < 3) && (!found))
{
lineA = triangleA.GetLine(im1);
if (count1 == 0)
{
lineA = new XYLine(lineA);
lineA.P1.X = p.X;
lineA.P1.Y = p.Y;
}
double MinDist = -1; // Distance used when a line is crossed more than once
int jm1 = 0; // "j-1"
int jm1Store = -1;
while (jm1 < 3)
{
lineB = triangleB.GetLine(jm1);
found = IntersectionPoint(lineA, lineB, ref p);
double Dist = CalculatePointToPointDistance(lineA.P1, p);
if (Dist < EPSILON)
{
found = false;
}
if (found)
{
if ((MinDist < 0) || (Dist < MinDist))
{
MinDist = Dist;
jm1Store = jm1;
}
}
jm1++;
}
if (jm1Store > -1)
{
lineB = triangleB.GetLine(jm1Store);
found = IntersectionPoint(lineA, lineB, ref p);
XYPoint HelpCoordinate = new XYPoint(p.X, p.Y);
XYPoint HelpNode = new XYPoint(HelpCoordinate);
intersectionPolygon.Points.Add(HelpNode);
j = Increase(jm1Store, 2);
}
if (!found)
{
count1++;
im1 = Increase(im1, 2);
i = Increase(i, 2);
if (j != -1)
{
XYPoint HelpCoordinate = new XYPoint(lineA.P2.X, lineA.P2.Y);
XYPoint HelpNode = new XYPoint(HelpCoordinate);
intersectionPolygon.Points.Add(HelpNode);
}
}
}
lineA = triangleA.GetLine(Decrease(i, 2));
if (CalculatePointToPointDistance(p, lineA.P2) < EPSILON)
{
i = Increase(i, 2);
}
lineB = triangleB.GetLine(Decrease(j, 2));
if (CalculatePointToPointDistance(p, lineB.P2) < EPSILON)
{
j = Increase(j, 2);
}
}
/// <summary>
/// Calculates length of line inside polygon. Parts of the line that is on the edge of
/// the polygon only counts with half their length.
/// </summary>
/// <param name="line">Line</param>
/// <param name="polygon">Polygon</param>
/// <returns>
/// Length of line inside polygon.
/// </returns>
protected static double CalculateLengthOfLineInsidePolygon(XYLine line, XYPolygon polygon)
{
var lineList = new List <XYLine> {
new XYLine(line)
};
for (int i = 0; i < polygon.Points.Count; i++) // For all lines in the polygon
{
for (int n = 0; n < lineList.Count; n++)
{
if (lineList.Count > 1000)
{
throw new Exception("Problems in ElementMapper, line has been cut in more than 1000 pieces !!!");
}
if (DoLineSegmentsIntersect((XYLine)lineList[n], polygon.GetLine(i)))
{
// Split the intersecting line into two lines
XYPoint IntersectionPoint = new XYPoint(CalculateIntersectionPoint((XYLine)lineList[n], polygon.GetLine(i)));
lineList.Add(new XYLine(IntersectionPoint, lineList[n].P2));
lineList[n].P2.X = IntersectionPoint.X;
lineList[n].P2.Y = IntersectionPoint.Y;
break;
}
}
}
for (int i = 0; i < lineList.Count; i++)
{
if (lineList.Count > 1000)
{
throw new Exception("Problems in ElementMapper, line has been cuttes in more than 100 pieces !!!");
}
for (int j = 0; j < polygon.Points.Count; j++)
{
if (IsPointInLineInterior(polygon.GetLine(j).P1, ((XYLine)lineList[i])))
{
lineList.Add(new XYLine(polygon.GetLine(j).P1, ((XYLine)lineList[i]).P2));
lineList[i].P2.X = polygon.GetLine(j).P1.X;
lineList[i].P2.Y = polygon.GetLine(j).P1.Y;
}
}
}
double lengthInside = 0;
for (int i = 0; i < lineList.Count; i++)
{
double sharedLength = 0;
for (int j = 0; j < polygon.Points.Count; j++)
{
sharedLength += CalculateSharedLength(((XYLine)lineList[i]), polygon.GetLine(j));
}
if (sharedLength > EPSILON)
{
lengthInside += sharedLength / 2;
}
else if (IsPointInPolygon(((XYLine)lineList[i]).GetMidpoint(), polygon))
{
lengthInside += ((XYLine)lineList[i]).GetLength();
}
}
return(lengthInside);
}
/// <summary>
/// Determines if a point in inside or outside a polygon. Inside
/// includes on the edge for this method.
/// Works for both convex and concave polygons (Winding number test)
/// </summary>
/// <param name="x">x-coordinate for the point</param>
/// <param name="y">y-coordiante for the point</param>
/// <param name="polygon">Polygon</param>
/// <returns>
/// <p>true: If the point is inside the polygon</p>
/// <p>false: If the point is outside the polygon.</p>
/// </returns>
protected static bool IsPointInPolygonOrOnEdge(double x, double y, XYPolygon polygon)
{
bool result = IsPointInPolygon(x, y, polygon);
if( result )
{
return result;
}
else
{
int iLine = 0;
while( (!result) && (iLine < polygon.Points.Count) )
{
XYLine line = new XYLine();
line = polygon.GetLine(iLine);
result = IsPointInLine(x, y, line);
iLine++;
}
}
return result;
}
/// <summary>
/// The method calculates the intersection points of triangle a and b both
/// of type XYPolygon.
/// </summary>
/// <param name="triangleA">triangle. The search is started along triangleA.</param>
/// <param name="triangleB">triangle. Intersection with this triangle are sought.</param>
/// <param name="p">Starting point for the search. p must be part of triangleA.</param>
/// <param name="i">on input: End index for the first line segment of triangleA in the search.
/// on output: End index for the last intersected line segment in triangleA.</param>
/// <param name="j">on input: -1 if vertices before intersection is not to be added to list.
/// on output: End index for last intersected line segment of triangleB.</param>
/// <param name="intersectionPolygon">polygon eventuallu describing the
/// intersection area between triangleA and triangleB</param>
/// <returns>
/// The p, i, j and intersectionPolygon are called by reference and modified in the method.
/// </returns>
private static void Intersect (XYPolygon triangleA, XYPolygon triangleB,
ref XYPoint p, ref int i, ref int j,
ref XYPolygon intersectionPolygon)
{
XYLine lineA;
XYLine lineB;
int im1 = Decrease(i, 2); // "i-1"
int count1 = 0;
bool found = false;
while ((count1 < 3) && (!found))
{
lineA = triangleA.GetLine(im1);
if (count1 == 0)
{
lineA.P1.X = p.X;
lineA.P1.Y = p.Y;
}
double MinDist = -1; // Distance used when a line is crossed more than once
int jm1 = 0; // "j-1"
int jm1Store = -1;
while (jm1 < 3)
{
lineB = triangleB.GetLine(jm1);
found = IntersectionPoint(lineA, lineB, ref p);
double Dist = CalculatePointToPointDistance(lineA.P1,p);
if (Dist < EPSILON)
{
found = false;
}
if (found)
{
if ((MinDist < 0) || (Dist < MinDist))
{
MinDist = Dist;
jm1Store = jm1;
}
}
jm1++;
}
if ( jm1Store > -1 )
{
lineB = triangleB.GetLine(jm1Store);
found = IntersectionPoint(lineA, lineB, ref p);
XYPoint HelpCoordinate = new XYPoint(p.X, p.Y);
XYPoint HelpNode = new XYPoint(HelpCoordinate);
intersectionPolygon.Points.Add(HelpNode);
j = Increase(jm1Store,2);
}
if (!found)
{
count1++;
im1 = Increase(im1,2);
i = Increase(i,2);
if (j!=-1)
{
XYPoint HelpCoordinate = new XYPoint(lineA.P2.X, lineA.P2.Y);
XYPoint HelpNode = new XYPoint(HelpCoordinate);
intersectionPolygon.Points.Add(HelpNode);
}
}
}
lineA = triangleA.GetLine(Decrease(i, 2));
if ( CalculatePointToPointDistance(p, lineA.P2)<EPSILON )
{
i = Increase(i, 2);
}
lineB = triangleB.GetLine(Decrease(j, 2));
if ( CalculatePointToPointDistance(p, lineB.P2)<EPSILON )
{
j = Increase(j, 2);
}
}
/// <summary>
/// Calculates length of line inside polygon. Parts of the line that is on the edge of
/// the polygon only counts with half their length.
/// </summary>
/// <param name="line">Line</param>
/// <param name="polygon">Polygon</param>
/// <returns>
/// Length of line inside polygon.
/// </returns>
protected static double CalculateLengthOfLineInsidePolygon(XYLine line, XYPolygon polygon)
{
ArrayList lineList = new ArrayList();
lineList.Add(new XYLine(line));
for (int i = 0; i < polygon.Points.Count; i++) // For all lines in the polygon
{
for (int n = 0; n < lineList.Count; n++)
{
if (lineList.Count > 1000)
{
throw new Exception("Problems in ElementMapper, line has been cut in more than 1000 pieces !!!");
}
if (DoLineSegmentsIntersect((XYLine)lineList[n], polygon.GetLine(i)))
{
// Split the intersecting line into two lines
XYPoint IntersectionPoint = new XYPoint(CalculateIntersectionPoint((XYLine)lineList[n], polygon.GetLine(i)));
lineList.Add(new XYLine(IntersectionPoint, ((XYLine) lineList[n]).P2));
((XYLine) lineList[n]).P2.X = IntersectionPoint.X;
((XYLine) lineList[n]).P2.Y = IntersectionPoint.Y;
break;
}
}
}
for (int i = 0; i < lineList.Count; i++)
{
if (lineList.Count > 1000)
{
throw new Exception("Problems in ElementMapper, line has been cuttes in more than 100 pieces !!!");
}
for (int j = 0; j < polygon.Points.Count; j++)
{
if (IsPointInLineInterior( polygon.GetLine(j).P1, ((XYLine) lineList[i])))
{
lineList.Add(new XYLine(polygon.GetLine(j).P1, ((XYLine) lineList[i]).P2));
((XYLine) lineList[i]).P2.X = polygon.GetLine(j).P1.X;
((XYLine) lineList[i]).P2.Y = polygon.GetLine(j).P1.Y;
}
}
}
double lengthInside = 0;
for (int i = 0; i < lineList.Count; i++)
{
double sharedLength = 0;
for (int j = 0; j < polygon.Points.Count; j++)
{
sharedLength += CalculateSharedLength(((XYLine) lineList[i]), polygon.GetLine(j));
}
if (sharedLength > EPSILON)
{
lengthInside += sharedLength/2;
}
else if (IsPointInPolygon(((XYLine) lineList[i]).GetMidpoint(), polygon))
{
lengthInside += ((XYLine) lineList[i]).GetLength();
}
}
return lengthInside;
}