private void InsertLocalMinima(LocalMinima newLm)
{
Contract.Requires(newLm != null);
if (MinimaList == null)
{
MinimaList = newLm;
}
else if (newLm.Y >= MinimaList.Y)
{
newLm.Next = MinimaList;
MinimaList = newLm;
}
else
{
var tmpLm = MinimaList;
while (tmpLm.Next != null && (newLm.Y < tmpLm.Next.Y))
tmpLm = tmpLm.Next;
newLm.Next = tmpLm.Next;
tmpLm.Next = newLm;
}
}
private TEdge AddBoundsToLML(TEdge e)
{
Contract.Requires(e != null);
Contract.Requires(e.Next != null);
//Starting at the top of one bound we progress to the bottom where there's
//a local minima. We then go to the top of the next bound. These two bounds
//form the left and right (or right and left) bounds of the local minima.
e.NextInLML = null;
e = e.Next;
for (; ; )
{
if (e.Dx == HORIZONTAL)
{
//nb: proceed through horizontals when approaching from their right,
// but break on horizontal minima if approaching from their left.
// This ensures 'local minima' are always on the left of horizontals.
if (e.Next.YTop < e.YTop && e.Next.XBot > e.Prev.XBot)
break;
if (e.XTop != e.Prev.XBot)
SwapX(e);
e.NextInLML = e.Prev;
}
else if (e.YCurr == e.Prev.YCurr)
break;
else
e.NextInLML = e.Prev;
e = e.Next;
}
//e and e.prev are now at a local minima ...
var newLm = new LocalMinima { Next = null, Y = e.Prev.YBot };
if (e.Dx == HORIZONTAL) //horizontal edges never start a left bound
{
if (e.XBot != e.Prev.XBot)
SwapX(e);
newLm.LeftBound = e.Prev;
newLm.RightBound = e;
}
else if (e.Dx < e.Prev.Dx)
{
newLm.LeftBound = e.Prev;
newLm.RightBound = e;
}
else
{
newLm.LeftBound = e;
newLm.RightBound = e.Prev;
}
newLm.LeftBound.Side = EdgeSide.Left;
newLm.RightBound.Side = EdgeSide.Right;
InsertLocalMinima(newLm);
for (; ; )
{
if (e.Next.YTop == e.YTop && e.Next.Dx != HORIZONTAL)
break;
e.NextInLML = e.Next;
e = e.Next;
if (e.Dx == HORIZONTAL && e.XBot != e.Prev.XTop)
SwapX(e);
}
return e.Next;
}
protected void PopLocalMinima()
{
if (CurrentLM == null)
return;
CurrentLM = CurrentLM.Next;
}
protected virtual void Reset()
{
CurrentLM = MinimaList;
//reset all edges ...
var lm = MinimaList;
while (lm != null)
{
var e = lm.LeftBound;
while (e != null)
{
e.XCurr = e.XBot;
e.YCurr = e.YBot;
e.Side = EdgeSide.Left;
e.OutIdx = -1;
e = e.NextInLML;
}
e = lm.RightBound;
while (e != null)
{
e.XCurr = e.XBot;
e.YCurr = e.YBot;
e.Side = EdgeSide.Right;
e.OutIdx = -1;
e = e.NextInLML;
}
lm = lm.Next;
}
}
// ReSharper disable once UnusedMemberHiearchy.Global
// ReSharper disable once MemberCanBeProtected.Global
public virtual void Clear()
{
MinimaList = null;
MinimaList = null;
Edges.Clear();
}
