/// <summary>
/// It is hard to create a situation where border segments change by
/// enough to cause an invalid geometry to be returned.
/// One way is to use a fixed precision model,
/// which will cause segments to move enough to
/// intersect with non-overlapping components.
/// <para/>
/// However, the current union algorithm
/// emits topology failures for these situations, since
/// it is not performing snap-rounding.
/// These exceptions are irrelevant to the correctness
/// of the OverlapUnion algorithm, so are prevented from being reported as a test failure.
/// </summary>
/// <param name="wktA"></param>
/// <param name="wktB"></param>
/// <param name="scaleFactor"></param>
private static void CheckUnionWithTopologyFailure(string wktA, string wktB, double scaleFactor)
{
var rdr = new WKTReader(new NtsGeometryServices(new PrecisionModel(scaleFactor), 0));
var a = rdr.Read(wktA);
var b = rdr.Read(wktB);
var union = new OverlapUnion(a, b);
Geometry result;
try
{
result = union.Union();
}
catch (TopologyException)
{
bool isOptimized = union.IsUnionOptimized;
// if the optimized algorithm was used then this is a real error
if (isOptimized)
{
throw;
}
// otherwise the error is probably due to the fixed precision
// not being handled by the current union code
return;
}
Assert.IsTrue(result.IsValid, "OverlapUnion result is invalid");
}
private static void CheckUnion(string wktA, string wktB, bool isCheckOptimized)
{
var rdr = new WKTReader();
var a = rdr.Read(wktA);
var b = rdr.Read(wktB);
var union = new OverlapUnion(a, b);
var result = union.Union();
if (isCheckOptimized)
{
bool isOptimized = union.IsUnionOptimized;
Assert.IsTrue(isOptimized, "Union was not performed using combine");
}
Assert.IsTrue(result.IsValid, "OverlapUnion result is invalid");
}