/// <summary>
/// Initializes a new instance of the <see cref="HotPixelSnapAction"/> class.
/// </summary>
/// <param name="hotPixel"></param>
/// <param name="parentEdge"></param>
/// <param name="vertexIndex"></param>
public HotPixelSnapAction(HotPixel hotPixel, SegmentString parentEdge, int vertexIndex)
{
this.hotPixel = hotPixel;
this.parentEdge = parentEdge;
this.vertexIndex = vertexIndex;
}
/// <summary>
/// Snaps (nodes) all interacting segments to this hot pixel.
/// The hot pixel may represent a vertex of an edge,
/// in which case this routine uses the optimization
/// of not noding the vertex itself
/// </summary>
/// <param name="hotPixel">The hot pixel to snap to.</param>
/// <param name="parentEdge">The edge containing the vertex, if applicable, or <c>null</c>.</param>
/// <param name="vertexIndex"></param>
/// <returns><c>true</c> if a node was added for this pixel.</returns>
public bool Snap(HotPixel hotPixel, SegmentString parentEdge, int vertexIndex)
{
Envelope pixelEnv = hotPixel.GetSafeEnvelope();
HotPixelSnapAction hotPixelSnapAction = new HotPixelSnapAction(hotPixel, parentEdge, vertexIndex);
index.Query(pixelEnv, new QueryVisitor(pixelEnv, hotPixelSnapAction));
return hotPixelSnapAction.IsNodeAdded;
}
/// <summary>
///
/// </summary>
/// <param name="hotPixel"></param>
/// <returns></returns>
public bool Snap(HotPixel hotPixel)
{
return Snap(hotPixel, null, -1);
}
/// <summary>
/// Adds a new node (equal to the snap pt) to the segment
/// if the segment passes through the hot pixel.
/// </summary>
/// <param name="hotPix"></param>
/// <param name="segStr"></param>
/// <param name="segIndex"></param>
/// <returns></returns>
public static bool AddSnappedNode(HotPixel hotPix, SegmentString segStr, int segIndex)
{
Coordinate p0 = segStr.GetCoordinate(segIndex);
Coordinate p1 = segStr.GetCoordinate(segIndex + 1);
if (hotPix.Intersects(p0, p1))
{
segStr.AddIntersection(hotPix.Coordinate, segIndex);
return true;
}
return false;
}
/// <summary>
/// Performs a brute-force comparison of every segment in each <see cref="SegmentString" />.
/// This has n^2 performance.
/// </summary>
/// <param name="e0"></param>
/// <param name="e1"></param>
private void ComputeVertexSnaps(SegmentString e0, SegmentString e1)
{
IList<Coordinate> pts0 = e0.Coordinates;
IList<Coordinate> pts1 = e1.Coordinates;
for (int i0 = 0; i0 < pts0.Count - 1; i0++)
{
HotPixel hotPixel = new HotPixel(pts0[i0], _scaleFactor, _li);
for (int i1 = 0; i1 < pts1.Count - 1; i1++)
{
// don't snap a vertex to itself
if (e0 == e1)
if (i0 == i1)
continue;
bool isNodeAdded = AddSnappedNode(hotPixel, e1, i1);
// if a node is created for a vertex, that vertex must be noded too
if (isNodeAdded)
e0.AddIntersection(pts0[i0], i0);
}
}
}
/// <summary>
///
/// </summary>
/// <param name="ss"></param>
/// <param name="snapPts"></param>
private void ComputeSnaps(SegmentString ss, IList snapPts)
{
foreach(object objo in snapPts)
{
Coordinate snapPt = (Coordinate)objo;
HotPixel hotPixel = new HotPixel(snapPt, _scaleFactor, _li);
for(int i = 0; i < ss.Count - 1; i++)
AddSnappedNode(hotPixel, ss, i);
}
}
/// <summary>
/// Performs a brute-force comparison of every segment in each <see cref="SegmentString" />.
/// This has n^2 performance.
/// </summary>
/// <param name="e"></param>
private void ComputeVertexSnaps(SegmentString e)
{
IList<Coordinate> pts0 = e.Coordinates;
for(int i = 0; i < pts0.Count - 1; i++)
{
HotPixel hotPixel = new HotPixel(pts0[i], _scaleFactor, _li);
bool isNodeAdded = _pointSnapper.Snap(hotPixel, e, i);
// if a node is created for a vertex, that vertex must be noded too
if (isNodeAdded)
e.AddIntersection(pts0[i], i);
}
}
/// <summary>
/// Computes nodes introduced as a result of snapping segments to snap points (hot pixels).
/// </summary>
/// <param name="snapPts"></param>
private void ComputeIntersectionSnaps(IList snapPts)
{
foreach(object obj in snapPts)
{
Coordinate snapPt = (Coordinate)obj;
HotPixel hotPixel = new HotPixel(snapPt, _scaleFactor, _li);
_pointSnapper.Snap(hotPixel);
}
}
