/// <summary>
/// Find cut lines through each polygon.
/// A polygon represents an area bounded by lines in the dual plane.
/// The cut line will be a point in the dual plane, being the line of greatest seperation in the real plane.
/// </summary>
/// <param name="a_region"></param>
/// <returns></returns>
public static List <Line> FindCutLinesInDual(IEnumerable <Polygon2D> a_region)
{
if (a_region.Count() <= 0) // no valid faces are supplied
{
return(new List <Line>());
}
//facebased approach
var lines = new List <Line>();
foreach (var poly in a_region.Skip(1).Take(a_region.Count() - 2)) //Treat faces on the bounding box separately
{
var line = Separator.LineOfGreatestMinimumSeparationInTheDual(poly, false).Line;
if (line == null)
{
throw new GeomException("Polygon should have a seperation line");
}
lines.Add(line);
}
// Solve bounding box cases (Take only the line with the greatest separation)
var firstBoundingboxPoly = a_region.ElementAt(0);
var lastBoundingboxPoly = a_region.ElementAt(a_region.Count() - 1);
var firstTuple = Separator.LineOfGreatestMinimumSeparationInTheDual(firstBoundingboxPoly, true);
var lastTuple = Separator.LineOfGreatestMinimumSeparationInTheDual(lastBoundingboxPoly, true);
if (firstTuple.Separation > lastTuple.Separation)
{
lines.Add(firstTuple.Line);
}
else
{
lines.Add(lastTuple.Line);
}
return(lines);
}
