// Build graph data structure in 'edges', 'centers', 'corners',
// based on information in the Voronoi results: point.neighbors
// will be a list of neighboring points of the same type (corner
// or center); point.edges will be a list of edges that include
// that point. Each edge connects to four points: the Voronoi edge
// edge.{v0,v1} and its dual Delaunay triangle edge edge.{d0,d1}.
// For boundary polygons, the Delaunay edge will have one null
// point, and the Voronoi edge may be null.
private void BuildGraph()
{
Voronoi voronoi = new Voronoi(pointsCount, new Rect(0, 0, width, height), NUM_LLOYD_ITERATIONS);
points = voronoi.GetPoints();
// Workaround for Voronoi lib bug: we need to call region()
// before Edges or neighboringSites are available
foreach (var center in _centers)
{
voronoi.Region(center.point);
}
List <Delaunay.Edge> libedges = voronoi.Edges();
Dictionary <Vector2, Center> centerLookup = new Dictionary <Vector2, Center>();
// Build Center objects for each of the points, and a lookup map
// to find those Center objects again as we build the graph
foreach (var point in points)
{
Center p = new Center();
p.index = _centers.Count;
p.point = point;
p.neighbors = new List <Center>();
p.borders = new List <DoubleEdge>();
p.corners = new List <Corner>();
_centers.Add(p);
centerLookup[point] = p;
}
Dictionary <int, List <Corner> > _cornerMap = new Dictionary <int, List <Corner> >();
foreach (Delaunay.Edge libedge in libedges)
{
LineSegment dedge = libedge.DelaunayLine();
LineSegment vedge = libedge.VoronoiEdge();
// Fill the graph data. Make an Edge object corresponding to
// the edge from the voronoi library.
DoubleEdge edge = new DoubleEdge();
edge.index = _edges.Count;
edge.river = 0;
if (vedge.p0 != null && vedge.p1 != null)
{
edge.midpoint = Vector2.Lerp((Vector2)vedge.p0, (Vector2)vedge.p1, 0.5f);
}
// Edges point to corners. Edges point to centers.
edge.v0 = MakeCorner(vedge.p0, _cornerMap);
edge.v1 = MakeCorner(vedge.p1, _cornerMap);
Center findCenter = null;
if (centerLookup.TryGetValue((Vector2)dedge.p0, out findCenter))
{
edge.d0 = findCenter;
}
else
{
edge.d0 = null;
}
if (centerLookup.TryGetValue((Vector2)dedge.p1, out findCenter))
{
edge.d1 = centerLookup[(Vector2)dedge.p1];
}
else
{
edge.d1 = null;
}
// Centers point to edges. Corners point to edges.
if (edge.d0 != null)
{
edge.d0.borders.Add(edge);
}
if (edge.d1 != null)
{
edge.d1.borders.Add(edge);
}
if (edge.v0 != null)
{
edge.v0.protrudes.Add(edge);
}
if (edge.v1 != null)
{
edge.v1.protrudes.Add(edge);
}
// Centers point to centers.
if (edge.d0 != null && edge.d1 != null)
{
AddToGenericList(edge.d0.neighbors, edge.d1);
AddToGenericList(edge.d1.neighbors, edge.d0);
}
// Corners point to corners
if (edge.v0 != null && edge.v1 != null)
{
AddToGenericList(edge.v0.adjacent, edge.v1);
AddToGenericList(edge.v1.adjacent, edge.v0);
}
// Centers point to corners
if (edge.d0 != null)
{
AddToGenericList(edge.d0.corners, edge.v0);
AddToGenericList(edge.d0.corners, edge.v1);
}
if (edge.d1 != null)
{
AddToGenericList(edge.d1.corners, edge.v0);
AddToGenericList(edge.d1.corners, edge.v1);
}
// Corners point to centers
if (edge.v0 != null)
{
AddToGenericList(edge.v0.touches, edge.d0);
AddToGenericList(edge.v0.touches, edge.d1);
}
if (edge.v1 != null)
{
AddToGenericList(edge.v1.touches, edge.d0);
AddToGenericList(edge.v1.touches, edge.d1);
}
_edges.Add(edge);
}
}