private SortedList <int, List <EdgeTableNode> > CreateEdgeTable(Polygon polygon, out int minY, out int maxY)
{
int key;
EdgeTableNode value;
SortedList <int, List <EdgeTableNode> > edgeTable = new SortedList <int, List <EdgeTableNode> >();
foreach (Edge edge in polygon.Edges)
{
if (edge.V1.Y > edge.V2.Y)
{
key = edge.V2.Y;
value = new EdgeTableNode(edge.V2.X, (edge.deltaX / (double)edge.deltaY), edge.V1.Y);
}
else
{
key = edge.V1.Y;
value = new EdgeTableNode(edge.V1.X, (edge.deltaX / (double)edge.deltaY), edge.V2.Y);
}
if (!edgeTable.ContainsKey(key))
{
edgeTable[key] = new List <EdgeTableNode>();
}
edgeTable[key].Add(value);
}
minY = polygon.Edges.Min(edge => Math.Min(edge.V1.Y, edge.V2.Y));
maxY = polygon.Edges.Max(edge => Math.Max(edge.V1.Y, edge.V2.Y));
return(edgeTable);
}
private void FillPolygon(Polygon polygon)
{
int minY, maxY;
SortedList <int, List <EdgeTableNode> > edgeTable = CreateEdgeTable(polygon, out minY, out maxY);
List <EdgeTableNode> activeEdgeTable = new List <EdgeTableNode>();
for (int y = minY; y <= maxY; ++y)
{
EdgeTableNode startNode = null, endNode = null;
foreach (EdgeTableNode node in activeEdgeTable)
{
if (startNode == null)
{
startNode = node;
}
else
{
endNode = node;
Parallel.For(Math.Max(0, startNode.X), endNode.X + 1, x =>
{
if (0 <= y && y < directBitmap.Height)
{
directBitmap[x, y] = surfaceRenderer.RenderPixel(x, y);
}
});
startNode = endNode = null;
}
}
if (edgeTable.ContainsKey(y))
{
activeEdgeTable.AddRange(edgeTable[y]);
}
activeEdgeTable.Sort((node1, node2) => node1.X - node2.X);
activeEdgeTable.RemoveAll(node => node.MaxY == y);
foreach (EdgeTableNode node in activeEdgeTable)
{
node.Increment();
}
}
}
