/// <summary>
/// Appends the coordinates to the queue.
/// </summary>
/// <param name="coordinates">The collection of coordinates.</param>
private void AppendCoordinates(IEnumerable <Coordinate> coordinates)
{
if (coordinates == null)
{
return;
}
IEnumerator <Coordinate> enumerator = coordinates.GetEnumerator();
if (!enumerator.MoveNext())
{
return;
}
Coordinate previous, current = enumerator.Current;
while (enumerator.MoveNext())
{
if (enumerator.Current == null)
{
continue;
}
previous = current;
current = enumerator.Current;
EndPointEvent firstEvent = new EndPointEvent {
Edge = this.coordinateCount, Vertex = previous
};
EndPointEvent secondEvent = new EndPointEvent {
Edge = this.coordinateCount, Vertex = current
};
Int32 compare = this.comparer.Compare(previous, current);
if (compare == 0)
{
continue;
}
if (compare < 0)
{
firstEvent.Type = EventType.Left;
secondEvent.Type = EventType.Right;
}
else
{
firstEvent.Type = EventType.Right;
secondEvent.Type = EventType.Left;
}
this.eventHeap.Insert(firstEvent);
this.eventHeap.Insert(secondEvent);
this.coordinateCount++;
}
this.coordinateCount++;
}
/// <summary>
/// Adds a new endpoint event to the sweep line.
/// </summary>
/// <param name="e">The event.</param>
/// <returns>The sweep line segment created by addition of <paramref name="e" />.</returns>
/// <exception cref="System.ArgumentNullException">The event is null.</exception>
/// <exception cref="System.ArgumentException">
/// The edge of the event is less than 0.
/// or
/// The edge of the event is greater than the number of edges in the source.
/// </exception>
public SweepLineSegment Add(EndPointEvent e)
{
if (e == null)
{
throw new ArgumentNullException(nameof(e));
}
if (e.Edge < 0)
{
throw new ArgumentException(CoreMessages.EventEdgeIsLessThan0, nameof(e));
}
if (e.Edge >= this.source.Count - 1)
{
throw new ArgumentException(CoreMessages.EventEdgeIsGreaterThanNumberOfEdges, nameof(e));
}
SweepLineSegment segment = new SweepLineSegment {
Edge = e.Edge
};
if (this.coordinateComparer.Compare(this.source[e.Edge], this.source[e.Edge + 1]) <= 0)
{
segment.LeftCoordinate = this.source[e.Edge];
segment.RightCoordinate = this.source[e.Edge + 1];
}
else
{
segment.LeftCoordinate = this.source[e.Edge + 1];
segment.RightCoordinate = this.source[e.Edge];
}
this.tree.Insert(segment);
SweepLineSegment segmentAbove = this.tree.GetNext();
SweepLineSegment segmentBelow = this.tree.GetPrevious();
if (segmentAbove != null)
{
segment.Above = segmentAbove;
segment.Above.Below = segment;
}
if (segmentBelow != null)
{
segment.Below = segmentBelow;
segment.Below.Above = segment;
}
return(segment);
}
/// <summary>
/// Searches the sweep line for an endpoint event.
/// </summary>
/// <param name="e">The event.</param>
/// <returns>The segment associated with the event.</returns>
/// <exception cref="System.ArgumentNullException">The event is null.</exception>
/// <exception cref="System.ArgumentException">
/// The edge of the event is less than 0.
/// or
/// The edge of the event is greater than the number of edges in the source.
/// </exception>
public SweepLineSegment Search(EndPointEvent e)
{
if (e == null)
{
throw new ArgumentNullException(nameof(e));
}
if (e.Edge < 0)
{
throw new ArgumentException(CoreMessages.EventEdgeIsLessThan0, nameof(e));
}
if (e.Edge >= this.source.Count - 1)
{
throw new ArgumentException(CoreMessages.EventEdgeIsGreaterThanNumberOfEdges, nameof(e));
}
SweepLineSegment segment = new SweepLineSegment()
{
Edge = e.Edge
};
if (this.coordinateComparer.Compare(this.source[e.Edge], this.source[e.Edge + 1]) < 0)
{
segment.LeftCoordinate = this.source[e.Edge];
segment.RightCoordinate = this.source[e.Edge + 1];
}
else
{
segment.LeftCoordinate = this.source[e.Edge + 1];
segment.RightCoordinate = this.source[e.Edge];
}
SweepLineSegment segmentResult;
if (this.tree.TrySearch(segment, out segmentResult))
{
return(segmentResult);
}
else
{
return(null);
}
}
/// <summary>
/// Compares two <see cref="Event" /> instances and returns a value indicating whether one is less than, equal to, or greater than the other.
/// </summary>
/// <remarks>
/// Events primarily compared by their vertex coordinate, secondarily by their type.
/// </remarks>
/// <param name="x">The first <see cref="Event" /> to compare.</param>
/// <param name="y">The second <see cref="Event" /> to compare.</param>
/// <returns>A signed integer that indicates the relative values of <paramref name="x" /> and <paramref name="y" />.</returns>
public Int32 Compare(Event x, Event y)
{
if (x == null || y == null)
{
return(0);
}
Int32 result = this.coordinateComparer.Compare(x.Vertex, y.Vertex);
if (result != 0)
{
return(result);
}
EndPointEvent ex = x as EndPointEvent;
EndPointEvent ey = y as EndPointEvent;
IntersectionEvent ix = x as IntersectionEvent;
IntersectionEvent iy = y as IntersectionEvent;
if (ex != null && ey != null)
{
result = ex.Type.CompareTo(ey.Type);
if (result == 0)
{
result = ex.Edge.CompareTo(ey.Edge);
}
}
else if (ix != null && iy != null)
{
if (result == 0)
{
result = this.coordinateComparer.Compare(ix.Below.LeftCoordinate, iy.Below.LeftCoordinate);
}
if (result == 0)
{
result = this.coordinateComparer.Compare(ix.Above.LeftCoordinate, iy.Above.LeftCoordinate);
}
if (result == 0)
{
result = this.coordinateComparer.Compare(ix.Below.RightCoordinate, iy.Below.RightCoordinate);
}
if (result == 0)
{
result = this.coordinateComparer.Compare(ix.Above.RightCoordinate, iy.Above.RightCoordinate);
}
if (result == 0)
{
result = ix.Below.Edge.CompareTo(iy.Below.Edge);
}
if (result == 0)
{
result = ix.Above.Edge.CompareTo(iy.Above.Edge);
}
if (result == 0)
{
result = ix.IsClosing.CompareTo(iy.IsClosing);
}
}
else if (ex != null && iy != null)
{
result = ex.Type == EventType.Left ? -1 : 1;
}
else if (ix != null && ey != null)
{
result = ey.Type == EventType.Left ? 1 : -1;
}
return(result);
}
