public static Color FromHsv(Angle h, double s, double v, int a)
{
var H = h.Degrees / 60;
s = GMath.Median(0, s, 1);
v = GMath.Median(0, v, 1);
var C = v * s;
var X = C * (1 - GMath.Abs(H % 2 - 1));
var m = v - C;
double R, G, B;
switch ((int)H)
{
case 0: R = C; G = X; B = 0; break;
case 1: R = X; G = C; B = 0; break;
case 2: R = 0; G = C; B = X; break;
case 3: R = 0; G = X; B = C; break;
case 4: R = X; G = 0; B = C; break;
default: R = C; G = 0; B = X; break;
}
return(FromRgba((int)(255 * (R + m)), (int)(255 * (G + m)), (int)(255 * (B + m)), a));
}
public static Polygon Ellipse(Point center, double xRadius, double yRadius)
{
int precision = (int)GMath.Ceiling(GMath.Pi * GMath.Abs(xRadius + yRadius));
if (precision <= 0)
{
return(new Polygon(new[] { center }));
}
double dt = GMath.Tau / precision;
double c = GMath.Cos(dt), s = GMath.Sin(dt);
double x = 1, y = 0, tmp;
var pts = new Point[precision];
for (int i = 0; i < precision; i++)
{
pts[i] = new Point(center.X + x * xRadius, center.Y + y * yRadius);
tmp = x;
x = c * x - s * y;
y = s * tmp + c * y;
}
return(new Polygon(pts));
}
public static Polygon Circle(Point center, double radius)
{
if (radius == 0)
{
return(new Polygon(new[] { center }));
}
int precision = (int)GMath.Ceiling(GMath.Tau * GMath.Abs(radius));
if (precision < 2)
{
precision = 2;
}
return(Regular(precision, radius, center));
}
public Polygon(IEnumerable <Point> pts)
{
_pts = pts.ToArray();
if (_pts.Length <= 2)
{
return;
}
double sum = 0;
Angle a;
Vector previous, next;
previous = Edge(-1).Offset;
next = Edge(0).Offset;
a = next.Direction - previous.Direction;
if (a.Degrees > 180)
{
Array.Reverse(_pts);
previous = Edge(-1).Offset;
next = Edge(0).Offset;
a = next.Direction - previous.Direction;
}
sum += a.Degrees;
for (int i = 1; i < _pts.Length; i++)
{
previous = next;
next = Edge(i).Offset;
a = next.Direction - previous.Direction;
if (a.Degrees > 180)
{
throw new ArgumentException("The points must specify a convex polygon.");
}
sum += a.Degrees;
}
if (GMath.Abs(sum - 360) > GMath.DefaultDelta)
{
throw new ArgumentException($"The points must specify a convex polygon with winding number equal to 1. (Winding is {sum} degrees)");
}
}
