/// <inheritdoc />
public IList <Tuple <IntVector2, bool> > OverlapAlongLine(TShape movingPolygon, TShape fixedPolygon, OrthogonalLine line)
{
var reverse = line.GetDirection() == OrthogonalLine.Direction.Bottom || line.GetDirection() == OrthogonalLine.Direction.Left;
if (reverse)
{
line = line.SwitchOrientation();
}
var rotation = line.ComputeRotation();
var rotatedLine = line.Rotate(rotation);
var movingDecomposition = GetDecomposition(movingPolygon).Select(x => x.Rotate(rotation)).ToList();
var fixedDecomposition = GetDecomposition(fixedPolygon).Select(x => x.Rotate(rotation)).ToList();
var smallestX = movingDecomposition.Min(x => x.A.X);
var events = new List <Tuple <IntVector2, bool> >();
// Compute the overlap for every rectangle in the decomposition of the moving polygon
foreach (var movingRectangle in movingDecomposition)
{
var newEvents = OverlapAlongLine(movingRectangle, fixedDecomposition, rotatedLine, movingRectangle.A.X - smallestX);
events = MergeEvents(events, newEvents, rotatedLine);
}
if (reverse)
{
events = ReverseEvents(events, rotatedLine);
}
return(events.Select(x => Tuple.Create(x.Item1.RotateAroundCenter(-rotation), x.Item2)).ToList());
}
/// <summary>
/// Returns a list of lines obtained by removing all the intersections from the original line.
/// </summary>
/// <param name="line"></param>
/// <param name="intersection"></param>
/// <returns></returns>
private List <OrthogonalLine> PartitionByIntersection(OrthogonalLine line, IList <OrthogonalLine> intersection)
{
var result = new List <OrthogonalLine>();
var rotation = line.ComputeRotation();
var rotatedLine = line.Rotate(rotation, true);
var directionVector = rotatedLine.GetDirectionVector();
var rotatedIntersection = intersection.Select(x => x.Rotate(rotation, false).GetNormalized()).ToList();
rotatedIntersection.Sort((x1, x2) => x1.From.CompareTo(x2.From));
var lastPoint = rotatedLine.From - directionVector;
foreach (var intersectionLine in rotatedIntersection)
{
if (intersectionLine.From != lastPoint && intersectionLine.From - directionVector != lastPoint)
{
result.Add(new OrthogonalLine(lastPoint + directionVector, intersectionLine.From - directionVector));
}
lastPoint = intersectionLine.To;
}
if (rotatedLine.To != lastPoint && rotatedLine.To - directionVector != lastPoint)
{
result.Add(new OrthogonalLine(lastPoint + directionVector, rotatedLine.To));
}
return(result.Select(x => x.Rotate(-rotation, false)).ToList());
}