public static List <Edge> GetLinesToFill(Polygon polygon)
{
EdgeTable edgeTable = PrepareEdgeTable(polygon);
EdgeList activeEdgeTable = new EdgeList();
List <Edge> pixelPairs = new List <Edge>();
int y = (int)polygon.GetMinY();
while (edgeTable.EdgeCount != 0 || activeEdgeTable.EdgeCount != 0)
{
EdgeList bucket = edgeTable.GetListAtIndex(y);
if (bucket != null)
{
activeEdgeTable.Append(bucket);
}
activeEdgeTable.SortByX();
activeEdgeTable.DeleteFinishedLines(y);
for (int i = 0; i < activeEdgeTable.EdgeCount; i += 2)
{
pixelPairs.Add(new Edge(new Vertex(new Point(activeEdgeTable[i].Xmin, y)), new Vertex(new Point(activeEdgeTable[i + 1].Xmin, y))));
}
y++;
activeEdgeTable.UpdateXmins();
}
return(pixelPairs);
}
private static EdgeTable PrepareEdgeTable(Polygon polygon)
{
EdgeTable edgeTable = new EdgeTable((int)polygon.GetMaxY() + 1);
foreach (Edge e in polygon.Edges)
{
if (e.Vertices[0].GetY() == e.Vertices[1].GetY())
{
continue;
}
EdgeNode node = new EdgeNode(e);
int index = (int)e.GetMinY();
edgeTable.AddAtIndex(index, node);
}
return(edgeTable);
}