private static Edge BuildMinimaBounds(LocalMinima localMinima, Edge edge)
{
var leftIsForward = edge.Dx > edge.Next.Dx;
// Assign left and right bounds
localMinima.LeftBound = leftIsForward ? edge.Next : edge;
localMinima.RightBound = leftIsForward ? edge : edge.Next;
// Build left and right bounds
var nextLeft = BuildBound(localMinima.LeftBound, leftIsForward);
var nextRight = BuildBound(localMinima.RightBound, !leftIsForward);
// Return the next edge to continue search
return(leftIsForward ? nextLeft : nextRight);
}
public static IList <LocalMinima> BuildLml(Edge boundaryStart)
{
var localMinimaList = new List <LocalMinima>();
Edge firstLocalMinimaEdge = null;
var edge = boundaryStart;
while (true)
{
if (!edge.EndIsLocalMinima)
{
edge = edge.Next;
continue;
}
if (edge == firstLocalMinimaEdge)
{
break;
}
if (firstLocalMinimaEdge == null)
{
firstLocalMinimaEdge = edge;
}
// Local minima found
var localMinima = new LocalMinima
{
// This is a local minima, so the bottom of this edge
// (the start vertex of the next edge) is the minima vertex.
Y = edge.Bottom.Y
};
// Add to the LML list
localMinimaList.Add(localMinima);
// Build left and right bounds, returns next edge after
// the forward bound.
var nextForwardEdge = BuildMinimaBounds(localMinima, edge);
// Move to the edge after right maxima
edge = nextForwardEdge;
}
return(localMinimaList);
}