public void FillPolygon(Polygon3D p)
{
//Tried using fill lines and storing them in the polygon. Had issues with concave polygons where it would draw outside of them because I didn't
//have mechanism like the parity bit flip. This is attempt two....
int Y = (int)(p.OrderByDescending(i => i.Y).First().Y);
int lowestY = (int)(p.OrderByDescending(i => i.Y).Last().Y);
int lowestX = (int)(p.OrderByDescending(i => i.X).Last().X);
int highestX = (int)(p.OrderByDescending(i => i.X).First().X);
while (Y >= lowestY)
{
List <Vector4 <double> > Intersections = new List <Vector4 <double> >();
List <Line3D> lines = p.GetLines();
for (int i = 0; i < lines.Count; i++)
{
Line3D scanLine = new Line3D(new Vector4 <double>(lowestX, Y, 1, 1), new Vector4 <double>(highestX, Y, 1, 1));
Vector4 <double> intPoint = Intersect(scanLine, lines[i]);
if (null != intPoint) // they interesected
{
if ((int)System.Math.Round(intPoint.Y) != lines[i].MaxY)
{
Intersections.Add(intPoint);
}
else
{
//we need to do something about the corners causing issues with rounding.
}
}
}
//sort items by x value so we can easily create lines
var sorted = Intersections.OrderBy(i => i.X).ToList();
while (sorted.Count > 1)
{
//Start at least x. Not using a parity bit. but this functions exactly the same way.
//Y stays constant while drawing. X is incremented
int x = (int)System.Math.Round(sorted[0].X, MidpointRounding.AwayFromZero);
//Start drawing and remove first point.
sorted.RemoveAt(0);
x++;
while (x < sorted[0].X)
{
WritePixel(x, Y, true);
x++;
}
sorted.RemoveAt(0);
}
Y--;
}
}