/// <summary>
///
/// </summary>
/// <param name="geomIndex"></param>
public void PropagateSideLabels(int geomIndex)
{
// Since edges are stored in CCW order around the node,
// As we move around the ring we move from the right to the left side of the edge
Location startLoc = Location.Null;
// initialize loc to location of last Curve side (if any)
foreach (EdgeEnd e in Edges)
{
Label label = e.Label;
if (label.IsArea(geomIndex) && label.GetLocation(geomIndex, Positions.Left) != Location.Null)
{
startLoc = label.GetLocation(geomIndex, Positions.Left);
}
}
// no labelled sides found, so no labels to propagate
if (startLoc == Location.Null)
{
return;
}
Location currLoc = startLoc;
foreach (EdgeEnd e in Edges)
{
Label label = e.Label;
// set null On values to be in current location
if (label.GetLocation(geomIndex, Positions.On) == Location.Null)
{
label.SetLocation(geomIndex, Positions.On, currLoc);
}
// set side labels (if any)
if (label.IsArea(geomIndex))
{
Location leftLoc = label.GetLocation(geomIndex, Positions.Left);
Location rightLoc = label.GetLocation(geomIndex, Positions.Right);
// if there is a right location, that is the next location to propagate
if (rightLoc != Location.Null)
{
if (rightLoc != currLoc)
{
throw new TopologyException("side location conflict", e.Coordinate);
}
if (leftLoc == Location.Null)
{
Assert.ShouldNeverReachHere("found single null side (at " + e.Coordinate + ")");
}
currLoc = leftLoc;
}
else
{
/* RHS is null - LHS must be null too.
* This must be an edge from the other point, which has no location
* labelling for this point. This edge must lie wholly inside or outside
* the other point (which is determined by the current location).
* Assign both sides to be the current location.
*/
Assert.IsTrue(label.GetLocation(geomIndex, Positions.Left) == Location.Null, "found single null side");
label.SetLocation(geomIndex, Positions.Right, currLoc);
label.SetLocation(geomIndex, Positions.Left, currLoc);
}
}
}
}
/// <summary>
///
/// </summary>
/// <param name="geomGraph"></param>
public virtual void ComputeLabelling(GeometryGraph[] geomGraph)
{
ComputeEdgeEndLabels(geomGraph[0].BoundaryNodeRule);
// Propagate side labels around the edges in the star
// for each parent Geometry
PropagateSideLabels(0);
PropagateSideLabels(1);
/*
* If there are edges that still have null labels for a point
* this must be because there are no area edges for that point incident on this node.
* In this case, to label the edge for that point we must test whether the
* edge is in the interior of the point.
* To do this it suffices to determine whether the node for the edge is in the interior of an area.
* If so, the edge has location Interior for the point.
* In all other cases (e.g. the node is on a line, on a point, or not on the point at all) the edge
* has the location Exterior for the point.
*
* Note that the edge cannot be on the Boundary of the point, since then
* there would have been a parallel edge from the Geometry at this node also labelled Boundary
* and this edge would have been labelled in the previous step.
*
* This code causes a problem when dimensional collapses are present, since it may try and
* determine the location of a node where a dimensional collapse has occurred.
* The point should be considered to be on the Exterior
* of the polygon, but locate() will return Interior, since it is passed
* the original Geometry, not the collapsed version.
*
* If there are incident edges which are Line edges labelled Boundary,
* then they must be edges resulting from dimensional collapses.
* In this case the other edges can be labelled Exterior for this Geometry.
*
* MD 8/11/01 - NOT True! The collapsed edges may in fact be in the interior of the Geometry,
* which means the other edges should be labelled Interior for this Geometry.
* Not sure how solve this... Possibly labelling needs to be split into several phases:
* area label propagation, symLabel merging, then finally null label resolution.
*/
bool[] hasDimensionalCollapseEdge = { false, false };
foreach (var e in Edges)
{
Label label = e.Label;
for (int geomi = 0; geomi < 2; geomi++)
{
if (label.IsLine(geomi) && label.GetLocation(geomi) == Location.Boundary)
{
hasDimensionalCollapseEdge[geomi] = true;
}
}
}
foreach (var e in Edges)
{
Label label = e.Label;
for (int geomi = 0; geomi < 2; geomi++)
{
if (label.IsAnyNull(geomi))
{
Location loc;
if (hasDimensionalCollapseEdge[geomi])
{
loc = Location.Exterior;
}
else
{
Coordinate p = e.Coordinate;
loc = GetLocation(geomi, p, geomGraph);
}
label.SetAllLocationsIfNull(geomi, loc);
}
}
}
}