double width( const double * py, double threshold, size_t spos, size_t tpos, size_t epos ) {
long xL = left_bound<double>( py, threshold, tpos, spos );
long xR = right_bound<double>( py, threshold, tpos, epos );
double Xl = left_intersection( py, xL, threshold );
double Xr = right_intersection( py, xR, threshold );
return Xr - Xl;
}
double width( const double * py, double threshold, uint32_t spos, uint32_t tpos, size_t epos ) {
int xL = left_bound<double>( py, threshold, tpos, spos );
int xR = right_bound<double>( py, threshold, tpos, epos );
Xl = left_intersection( py, xL, spos, threshold );
Xr = right_intersection( py, xR, epos, threshold );
return Xr - Xl;
}
double centerX( const double * py, double threshold, size_t spos, size_t tpos, size_t epos ) {
long xL = left_bound<double>( py, threshold, tpos, spos );
long xR = right_bound<double>( py, threshold, tpos, epos );
double Xl = left_intersection( py, xL, threshold );
double Xr = right_intersection( py, xR, threshold );
double x0 = fx_( xL - 1 );
double ma = 0;
double ta = 0;
double baseH = threshold;
{
// left triangle
//
// 90deg rotated triangle (h == time axis)
// /|
// / | h A = (1/2) a * h;
// /__| Gy = (1/3) * h
// a
double h = fx_( xL ) - Xl;
double a = py[xL] - baseH;
double area = h * a / 2;
double Gy = h / 3;
double cx = fx_( xL ) - Gy - x0;
ta += area;
ma += area * cx;
}
{
// right triangle
double h = Xr - fx_( xR );
double a = py[xR] - baseH;
double area = h * a / 2;
double Gy = h / 3;
double cx = fx_( xR ) + Gy - x0;
ta += area;
ma += area * cx;
}
//ta = aL + aR;
//ma = mL + mR;
for (long x = xL; x < xR; ++x) {
// 90 deg rotated trapezium
// c
// ________
// / | A = (1/2) * (a + c) * h;
// d / Gy | b = h h(a + 2c)
// /_________| Gy = ------------
// a 3(a + c)
//
double h = fx_( x + 1 ) - fx_( x );
double a = py[x + 1] - baseH;
double c = py[x] - baseH;
double Gy = (h * (a + 2 * c)) / (3 * (a + c));
double area = (c + a) * h / 2;
ta += area;
double cx = ( fx_( x + 1 ) - Gy) - x0;
ma += area * cx;
};
double xc = ma / ta + x0;
return xc;
};
