private Point CalculatorCenter(Point cRc1, Point cRc2, Point cRc3)
{
Point midPoint1 = new Point((int)(cRc1.X + cRc2.X) / 2, (int)(cRc1.Y + cRc2.Y) / 2);
Point midPoint2 = new Point((int)(cRc3.X + cRc2.X) / 2, (int)(cRc3.Y + cRc2.Y) / 2);
// y = ax+b
phuongtrinhduongthang dt1 = giahephuongtrinh(cRc1, cRc2);
phuongtrinhduongthang dt2 = giahephuongtrinh(cRc2, cRc3);
phuongtrinhvuonggoc(ref dt1, midPoint1);
phuongtrinhvuonggoc(ref dt2, midPoint2);
Point result = GetCenter(dt1, dt2);
return(result);
}
private Point GetCenter(phuongtrinhduongthang dt1, phuongtrinhduongthang dt2)
{
Point center = new Point();
/*
* y = a1x + b1 => x = (b2-b1)/ (a1-a2)
* y = a2x + b2
*
*/
center.X = (int)((dt2.b - dt1.b) / (dt1.a - dt2.a));
center.Y = (int)(dt2.a * center.X + dt2.b);
return(center);
}
private phuongtrinhduongthang giahephuongtrinh(Point point1, Point point2)
{
phuongtrinhduongthang result = new phuongtrinhduongthang();
/*
* y1 = ax1 + b
* y2 = ax2 + b
* => a = (y1-y2)/(x1-x2)
* => b = y1/a*x1
*
*/
result.a = (double)(point1.Y - point2.Y) / (point1.X - point2.X);
result.b = (double)point2.Y - (result.a * point2.X);
// convert to ax+by+c = 0
return(result);
}
private void phuongtrinhvuonggoc(ref phuongtrinhduongthang dtvg, Point mid)
{
dtvg.a = -1 / dtvg.a;
// y = ax+ b
dtvg.b = mid.Y - dtvg.a * mid.X;
}
