public static bool CircleToCircle(Circle a, Circle b)
{
double c2 = (a.cX - b.cX) * (a.cX - b.cX) + (a.cY - b.cY) * (a.cY - b.cY);
double r2 = (a.R + b.R) * (a.R + b.R);
return c2 <= r2;
}
public static bool CircleToRectangle(Circle a, Rectangle b)
{
double dmin = 0;
double[] C = new double[] { a.cX, a.cY };
double[] Bmin = new double[] { b.X, b.Y };
double[] Bmax = new double[] { b.X + b.W, b.Y + b.H };
for (int i = 0; i < C.Length; i++)
{
if (C[i] < Bmin[i]) dmin += (C[i] - Bmin[i]) * (C[i] - Bmin[i]);
else if (C[i] > Bmax[i]) dmin += (C[i] - Bmax[i]) * (C[i] - Bmax[i]);
}
return dmin <= a.R * a.R;
}