public static Texture2D Ellipse(this Texture2D texture, Vector2 position, Vector2 radius, Color color)
{
var p = position;
var s = texture.GetSize();
int w = (int)s.x;
var sx = new Vector2(0, s.x - 1);
var sy = new Vector2(0, s.y - 1);
Color[] pixels = texture.GetPixels();
// from: ftp://pc.fk0.name/pub/books/programming/bezier-ellipse.pdf
int cX = MathfEx.Round(position.x);
int cY = MathfEx.Round(position.y);
int TwoASquare = MathfEx.Round(2 * radius.x * radius.x);
int TwoBSquare = MathfEx.Round(2 * radius.y * radius.y);
int X = MathfEx.Round(radius.x);
int Y = 0;
int XChange = MathfEx.Round(radius.y * radius.y * (1 - 2 * radius.x));
int YChange = MathfEx.Round(radius.x * radius.x);
int EllipseError = 0;
int StoppingX = MathfEx.Round(TwoBSquare * radius.x);
int StoppingY = 0;
int o;
while (StoppingX >= StoppingY)
{
o = sy.Clamp(cY - Y) * w;
for (int i = sx.Clamp(cX - X); i <= sx.Clamp(cX + X); i++)
{
pixels[i + o] = color;
}
o = sy.Clamp(cY + Y) * w;
for (int i = sx.Clamp(cX - X); i <= sx.Clamp(cX + X); i++)
{
pixels[i + o] = color;
}
Y++;
StoppingY += TwoASquare;
EllipseError += YChange;
YChange += TwoASquare;
if ((2 * EllipseError + XChange) > 0)
{
X--;
StoppingX -= TwoBSquare;
EllipseError += XChange;
XChange += TwoBSquare;
}
}
X = 0;
Y = MathfEx.Round(radius.y);
XChange = MathfEx.Round(radius.y * radius.y);
YChange = MathfEx.Round(radius.x * radius.x * (1 - 2 * radius.y));
EllipseError = 0;
StoppingX = 0;
StoppingY = MathfEx.Round(TwoASquare * radius.y);
while (StoppingX <= StoppingY)
{
o = sy.Clamp(cY - Y) * w;
for (int i = sx.Clamp(cX - X); i <= sx.Clamp(cX + X); i++)
{
pixels[i + o] = color;
}
o = sy.Clamp(cY + Y) * w;
for (int i = sx.Clamp(cX - X); i <= sx.Clamp(cX + X); i++)
{
pixels[i + o] = color;
}
X++;
StoppingX += TwoBSquare;
EllipseError += XChange;
XChange += TwoBSquare;
if ((2 * EllipseError + YChange) > 0)
{
Y--;
StoppingY -= TwoASquare;
EllipseError += YChange;
YChange += TwoASquare;
}
}
texture.SetPixels(pixels);
texture.Apply();
return(texture);
}
