public void Test2Lines() {
RobustLineIntersector i = new RobustLineIntersector();
Coordinate p1 = new Coordinate(10, 10);
Coordinate p2 = new Coordinate(20, 20);
Coordinate q1 = new Coordinate(20, 10);
Coordinate q2 = new Coordinate(10, 20);
Coordinate x = new Coordinate(15, 15);
i.ComputeIntersection(p1, p2, q1, q2);
Assert.AreEqual(RobustLineIntersector.DoIntersect, i.IntersectionNum);
Assert.AreEqual(1, i.IntersectionNum);
Assert.AreEqual(x, i.GetIntersection(0));
Assert.IsTrue(i.IsProper);
Assert.IsTrue(i.HasIntersection);
}
public static IGeometry SegmentIntersection(IGeometry g1, IGeometry g2)
{
Coordinate[] pt1 = g1.Coordinates;
Coordinate[] pt2 = g2.Coordinates;
RobustLineIntersector ri = new RobustLineIntersector();
ri.ComputeIntersection(pt1[0], pt1[1], pt2[0], pt2[1]);
switch (ri.IntersectionNum)
{
case 0:
// no intersection => return empty point
return g1.Factory.CreatePoint((Coordinate)null);
case 1:
// return point
return g1.Factory.CreatePoint(ri.GetIntersection(0));
case 2:
// return line
return g1.Factory.CreateLineString(
new Coordinate[] {
ri.GetIntersection(0),
ri.GetIntersection(1)
});
}
return null;
}
/// <summary>
/// Computes an intersection point between two segments, if there is one.
/// There may be 0, 1 or many intersection points between two segments.
/// If there are 0, null is returned. If there is 1 or more, a single one
/// is returned (chosen at the discretion of the algorithm). If
/// more information is required about the details of the intersection,
/// the {RobustLineIntersector} class should be used.
/// </summary>
/// <param name="line">A line segment</param>
/// <returns> An intersection point, or <c>null</c> if there is none.</returns>
/// <see cref="RobustLineIntersector"/>
public Coordinate Intersection(LineSegment line)
{
LineIntersector li = new RobustLineIntersector();
li.ComputeIntersection(_p0, _p1, line._p0, line._p1);
if (li.HasIntersection)
return li.GetIntersection(0);
return null;
}
/// <summary>
/// Check that intersection of segment defined by points in pt array
/// is equal to the expectedIntPt value (up to the given distanceTolerance)
/// </summary>
/// <param name="pt"></param>
/// <param name="expectedIntersectionNum"></param>
/// <param name="expectedIntPt">the expected intersection points (maybe null if not tested)</param>
/// <param name="distanceTolerance">tolerance to use for equality test</param>
private void CheckIntersection(Coordinate[] pt,
int expectedIntersectionNum,
Coordinate[] expectedIntPt,
double distanceTolerance)
{
LineIntersector li = new RobustLineIntersector();
li.ComputeIntersection(pt[0], pt[1], pt[2], pt[3]);
int intNum = li.IntersectionNum;
Assert.AreEqual(expectedIntersectionNum, intNum, "Number of intersections not as expected");
if (expectedIntPt != null)
{
Assert.AreEqual(intNum, expectedIntPt.Length, "Wrong number of expected int pts provided");
// test that both points are represented here
if (intNum == 1)
{
CheckIntPoints(expectedIntPt[0], li.GetIntersection(0), distanceTolerance);
}
else if (intNum == 2)
{
CheckIntPoints(expectedIntPt[1], li.GetIntersection(0), distanceTolerance);
CheckIntPoints(expectedIntPt[1], li.GetIntersection(0), distanceTolerance);
if (!(Equals(expectedIntPt[0], li.GetIntersection(0), distanceTolerance)
|| Equals(expectedIntPt[0], li.GetIntersection(1), distanceTolerance)))
{
CheckIntPoints(expectedIntPt[0], li.GetIntersection(0), distanceTolerance);
CheckIntPoints(expectedIntPt[0], li.GetIntersection(1), distanceTolerance);
}
else if (!(Equals(expectedIntPt[1], li.GetIntersection(0), distanceTolerance)
|| Equals(expectedIntPt[1], li.GetIntersection(1), distanceTolerance)))
{
CheckIntPoints(expectedIntPt[1], li.GetIntersection(0), distanceTolerance);
CheckIntPoints(expectedIntPt[1], li.GetIntersection(1), distanceTolerance);
}
}
}
}
