bool
operator()(Point a, Point b) {
// not remove this check or std::sort could crash
if (a == b) return false;
Point da = a - o;
Point db = b - o;
if (da == -db) return false;
#if 1
double aa = da[0];
double ab = db[0];
if((da[1] == 0) && (db[1] == 0))
return da[0] < db[0];
if(da[1] == 0)
return true; // infinite tangent
if(db[1] == 0)
return false; // infinite tangent
aa = da[0] / da[1];
ab = db[0] / db[1];
if(aa > ab)
return true;
#else
//assert((ata > atb) == (aa < ab));
double aa = atan2(da);
double ab = atan2(db);
if(aa < ab)
return true;
#endif
if(aa == ab)
return L2sq(da) < L2sq(db);
return false;
}
bool operator() (Point const& a, Point const& b)
{
// not remove this check or std::sort could generate
// a segmentation fault because it needs a strict '<'
// but due to round errors a == b doesn't mean dxy == dyx
if (a == b) return false;
Point da = a - o;
Point db = b - o;
if (da == -db) return false;
double dxy = da[X] * db[Y];
double dyx = da[Y] * db[X];
if (dxy > dyx) return true;
else if (dxy < dyx) return false;
return L2sq(da) < L2sq(db);
}
/*
* NOTE: this implementation follows Standard SVG 1.1 implementation guidelines
* for elliptical arc curves. See Appendix F.6.
*/
void EllipticalArc::_updateCenterAndAngles(bool svg)
{
Point d = initialPoint() - finalPoint();
// TODO move this to SVGElipticalArc?
if (svg)
{
if ( initialPoint() == finalPoint() )
{
_rot_angle = _start_angle = _end_angle = 0;
_center = initialPoint();
_rays = Geom::Point(0,0);
_large_arc = _sweep = false;
return;
}
_rays[X] = std::fabs(_rays[X]);
_rays[Y] = std::fabs(_rays[Y]);
if ( are_near(ray(X), 0) || are_near(ray(Y), 0) )
{
_rays[X] = L2(d) / 2;
_rays[Y] = 0;
_rot_angle = std::atan2(d[Y], d[X]);
_start_angle = 0;
_end_angle = M_PI;
_center = middle_point(initialPoint(), finalPoint());
_large_arc = false;
_sweep = false;
return;
}
}
else
{
if ( are_near(initialPoint(), finalPoint()) )
{
if ( are_near(ray(X), 0) && are_near(ray(Y), 0) )
{
_start_angle = _end_angle = 0;
_center = initialPoint();
return;
}
else
{
THROW_RANGEERROR("initial and final point are the same");
}
}
if ( are_near(ray(X), 0) && are_near(ray(Y), 0) )
{ // but initialPoint != finalPoint
THROW_RANGEERROR(
"there is no ellipse that satisfies the given constraints: "
"ray(X) == 0 && ray(Y) == 0 but initialPoint != finalPoint"
);
}
if ( are_near(ray(Y), 0) )
{
Point v = initialPoint() - finalPoint();
if ( are_near(L2sq(v), 4*ray(X)*ray(X)) )
{
Angle angle(v);
if ( are_near( angle, _rot_angle ) )
{
_start_angle = 0;
_end_angle = M_PI;
_center = v/2 + finalPoint();
return;
}
angle -= M_PI;
if ( are_near( angle, _rot_angle ) )
{
_start_angle = M_PI;
_end_angle = 0;
_center = v/2 + finalPoint();
return;
}
THROW_RANGEERROR(
"there is no ellipse that satisfies the given constraints: "
"ray(Y) == 0 "
"and slope(initialPoint - finalPoint) != rotation_angle "
"and != rotation_angle + PI"
);
}
if ( L2sq(v) > 4*ray(X)*ray(X) )
{
THROW_RANGEERROR(
"there is no ellipse that satisfies the given constraints: "
"ray(Y) == 0 and distance(initialPoint, finalPoint) > 2*ray(X)"
);
}
else
{
THROW_RANGEERROR(
"there is infinite ellipses that satisfy the given constraints: "
"ray(Y) == 0 and distance(initialPoint, finalPoint) < 2*ray(X)"
);
}
}
if ( are_near(ray(X), 0) )
{
Point v = initialPoint() - finalPoint();
if ( are_near(L2sq(v), 4*ray(Y)*ray(Y)) )
{
double angle = std::atan2(v[Y], v[X]);
if (angle < 0) angle += 2*M_PI;
double rot_angle = _rot_angle.radians() + M_PI/2;
if ( !(rot_angle < 2*M_PI) ) rot_angle -= 2*M_PI;
if ( are_near( angle, rot_angle ) )
{
_start_angle = M_PI/2;
_end_angle = 3*M_PI/2;
_center = v/2 + finalPoint();
return;
}
angle -= M_PI;
if ( angle < 0 ) angle += 2*M_PI;
if ( are_near( angle, rot_angle ) )
{
_start_angle = 3*M_PI/2;
_end_angle = M_PI/2;
_center = v/2 + finalPoint();
return;
}
THROW_RANGEERROR(
"there is no ellipse that satisfies the given constraints: "
"ray(X) == 0 "
"and slope(initialPoint - finalPoint) != rotation_angle + PI/2 "
"and != rotation_angle + (3/2)*PI"
);
}
if ( L2sq(v) > 4*ray(Y)*ray(Y) )
{
THROW_RANGEERROR(
"there is no ellipse that satisfies the given constraints: "
"ray(X) == 0 and distance(initialPoint, finalPoint) > 2*ray(Y)"
);
}
else
{
THROW_RANGEERROR(
"there is infinite ellipses that satisfy the given constraints: "
"ray(X) == 0 and distance(initialPoint, finalPoint) < 2*ray(Y)"
);
}
}
}
Rotate rm(_rot_angle);
Affine m(rm);
m[1] = -m[1];
m[2] = -m[2];
Point p = (d / 2) * m;
double rx2 = _rays[X] * _rays[X];
double ry2 = _rays[Y] * _rays[Y];
double rxpy = _rays[X] * p[Y];
double rypx = _rays[Y] * p[X];
double rx2py2 = rxpy * rxpy;
double ry2px2 = rypx * rypx;
double num = rx2 * ry2;
double den = rx2py2 + ry2px2;
assert(den != 0);
double rad = num / den;
Point c(0,0);
if (rad > 1)
{
rad -= 1;
rad = std::sqrt(rad);
if (_large_arc == _sweep) rad = -rad;
c = rad * Point(rxpy / ray(Y), -rypx / ray(X));
_center = c * rm + middle_point(initialPoint(), finalPoint());
}
else if (rad == 1 || svg)
{
double lamda = std::sqrt(1 / rad);
_rays[X] *= lamda;
_rays[Y] *= lamda;
_center = middle_point(initialPoint(), finalPoint());
}
else
{
THROW_RANGEERROR(
"there is no ellipse that satisfies the given constraints"
);
}
Point sp((p[X] - c[X]) / ray(X), (p[Y] - c[Y]) / ray(Y));
Point ep((-p[X] - c[X]) / ray(X), (-p[Y] - c[Y]) / ray(Y));
Point v(1, 0);
_start_angle = angle_between(v, sp);
double sweep_angle = angle_between(sp, ep);
if (!_sweep && sweep_angle > 0) sweep_angle -= 2*M_PI;
if (_sweep && sweep_angle < 0) sweep_angle += 2*M_PI;
_end_angle = _start_angle;
_end_angle += sweep_angle;
}
