protected unsafe override void RenderLine (ISurface src, ISurface dst, Rectangle rect)
{
float twist = amount;
float hw = dst.Width / 2.0f;
float hh = dst.Height / 2.0f;
float maxrad = Math.Min (hw, hh);
twist = twist * twist * Math.Sign (twist);
int aaLevel = antialias;
int aaSamples = aaLevel * aaLevel + 1;
PointD* aaPoints = stackalloc PointD[aaSamples];
for (int i = 0; i < aaSamples; ++i) {
PointD pt = new PointD (
((i * aaLevel) / (float)aaSamples),
i / (float)aaSamples);
pt.X -= (int)pt.X;
aaPoints[i] = pt;
}
for (int y = rect.Top; y <= rect.Bottom; y++) {
float j = y - hh;
ColorBgra* dstPtr = dst.GetPointAddress (rect.Left, y);
ColorBgra* srcPtr = src.GetPointAddress (rect.Left, y);
for (int x = rect.Left; x <= rect.Right; x++) {
float i = x - hw;
if (i * i + j * j > (maxrad + 1) * (maxrad + 1)) {
*dstPtr = *srcPtr;
} else {
int b = 0;
int g = 0;
int r = 0;
int a = 0;
for (int p = 0; p < aaSamples; ++p) {
float u = i + (float)aaPoints[p].X;
float v = j + (float)aaPoints[p].Y;
double rad = Math.Sqrt (u * u + v * v);
double theta = Math.Atan2 (v, u);
double t = 1 - rad / maxrad;
t = (t < 0) ? 0 : (t * t * t);
theta += (t * twist) / 100;
ColorBgra sample = src.GetPoint (
(int)(hw + (float)(rad * Math.Cos (theta))),
(int)(hh + (float)(rad * Math.Sin (theta))));
b += sample.B;
g += sample.G;
r += sample.R;
a += sample.A;
}
*dstPtr = ColorBgra.FromBgra (
(byte)(b / aaSamples),
(byte)(g / aaSamples),
(byte)(r / aaSamples),
(byte)(a / aaSamples));
}
++dstPtr;
++srcPtr;
}
}
}
#endregion
