public EdgePointer(int ymax, double x, double m, EdgePointer next)
{
this.ymax = ymax;
this.x = x;
this.m = m;
this.next = next;
}
void FillPoly(Polygon p)
{
EdgePointer[] ET = new EdgePointer[2000];
int ymin, ymax, x, ystart = p.points[0].Y;
double m;
int count = p.points.Count;
for (int i = 0; i < p.points.Count; i++)
{
ymin = p.points[i].Y;
ymax = p.points[(i + 1) % p.points.Count].Y;
x = p.points[i].X;
m = (double)(ymin - ymax) / (double)(x - p.points[(i + 1) % p.points.Count].X);
m = 1 / m;
if (ymax < ymin)
{
int t = ymin;
ymin = ymax;
ymax = t;
x = p.points[(i + 1) % p.points.Count].X;
}
else if (ymax == ymin)
{
count--;
continue;
}
if (ET[ymin] == null)
{
ET[ymin] = new EdgePointer(ymax, x, m, null);
}
else
{
EdgePointer pt = ET[ymin];
while (pt.next != null)
{
pt = pt.next;
}
pt.next = new EdgePointer(ymax, x, m, null);
}
if (ystart > ymin)
{
ystart = ymin;
}
}
List <EdgePointer> AET = new List <EdgePointer>();
while ((count != 0 || AET.Count != 0) && ystart < DrawArea.Height)
{
EdgePointer pty = ET[ystart];
while (pty != null)
{
AET.Add(pty);
pty = pty.next;
count--;
}
AET.Sort((x1, x2) => (int)(x1.x - x2.x));
for (int i = 0; i < AET.Count; i += 2)
{
int xa1 = (int)AET[i].x + 1;
int xa2 = (int)AET[i + 1].x;
if (InterpolationCheckBox.Checked)
{
Color Left = GetColor(xa1, ystart);
Color Right = GetColor(xa2, ystart);
DrawPixel(xa1, ystart, Left);
DrawPixel(xa2, ystart, Right);
for (int j = xa1 + 1; j < xa2; j++)
{
DrawPixel(j, ystart, InterpolateColor(xa1, xa2, j, Left, Right));
}
}
else
{
for (int j = xa1; j <= xa2; j++)
{
DrawPixel(j, ystart, GetColor(j, ystart));
}
}
}
ystart++;
AET.RemoveAll(x1 => x1.ymax == ystart);
foreach (var e in AET)
{
e.x += e.m;
}
}
}