/// <summary>
/// Split this region into two (or more) sub-regions along a straight line
/// </summary>
/// <param name="splitPt">A point on the splitting line</param>
/// <param name="splitDir">The direction of the line</param>
/// <param name="splitWidth">Optional. The width of the split.</param>
/// <returns>The resultant list of regions. If the line does not bisect
/// this region and the region could not be split, this collection will contain
/// only the original region.</returns>
public IList <PlanarRegion> SplitByLineXY(Vector splitPt, Vector splitDir, double splitWidth = 0)
{
var result = new List <PlanarRegion>();
var outerInts = Intersect.CurveLineXY(Perimeter, splitPt, splitDir).ToList();
outerInts.Sort();
//TODO: void intersections
// Commented out as not finished:
/*foreach (var voidCrv in Voids)
* {
* IList<double> voidInts = Intersect.CurveLineXY(voidCrv, splitPt, splitDir);
* }*/
if (outerInts.Count > 1)
{
for (int i = 0; i < outerInts.Count; i++)
{
double t0 = outerInts[i];
double t1 = outerInts.GetWrapped(i + 1);
Curve newPerimeter = Perimeter.Extract(new Interval(t0, t1))?.ToPolyCurve();
//TODO: Cut through and include voids
if (!newPerimeter.Closed)
{
((PolyCurve)newPerimeter).Close();
if (splitWidth > 0)
{
var offsets = new double[newPerimeter.SegmentCount];
offsets[offsets.Length - 1] = splitWidth / 2;
var newNewPerimeter = newPerimeter.OffsetInwards(offsets);
// Check offset has not inverted perimeter:
// TODO: Do this automatically when offsetting?
if (newNewPerimeter != null && newNewPerimeter.IsClockwiseXY() == newPerimeter.IsClockwiseXY())
{
newPerimeter = newNewPerimeter;
}
else
{
newPerimeter = null;
}
}
}
if (newPerimeter != null)
{
result.Add(new PlanarRegion(newPerimeter, Attributes?.Duplicate()));
}
}
}
else
{
result.Add(this); //Return the original
}
return(result);
}