MinimalBoundingSphere::MinimalBoundingSphere(MathLib::Point3d const& p,
MathLib::Point3d const& q, MathLib::Point3d const& r)
{
MathLib::Vector3 const a(p,r);
MathLib::Vector3 const b(p,q);
MathLib::Vector3 const cross_ab(crossProduct(a,b));
if (cross_ab.getLength() > 0)
{
double const denom = 2.0 * scalarProduct(cross_ab,cross_ab);
MathLib::Vector3 const o = (scalarProduct(b,b) * crossProduct(cross_ab, a)
+ scalarProduct(a,a) * crossProduct(b, cross_ab))
* (1.0 / denom);
_radius = o.getLength() + std::numeric_limits<double>::epsilon();
_center = MathLib::Vector3(p) + o;
}
else
{
MinimalBoundingSphere two_pnts_sphere;
if (a.getLength() > b.getLength())
two_pnts_sphere = MinimalBoundingSphere(p,r);
else
two_pnts_sphere = MinimalBoundingSphere(p,q);
_radius = two_pnts_sphere.getRadius();
_center = two_pnts_sphere.getCenter();
}
}
MinimalBoundingSphere::MinimalBoundingSphere(
MathLib::Point3d const& p, MathLib::Point3d const& q)
: _radius(std::numeric_limits<double>::epsilon()), _center(p)
{
MathLib::Vector3 const a(p, q);
if (a.getLength() > 0)
{
MathLib::Vector3 const o(0.5*a);
_radius = o.getLength() + std::numeric_limits<double>::epsilon();
_center = MathLib::Vector3(p) + o;
}
}
MinimalBoundingSphere::MinimalBoundingSphere(MathLib::Point3d const& p,
MathLib::Point3d const& q,
MathLib::Point3d const& r,
MathLib::Point3d const& s)
{
MathLib::Vector3 const a(p, q);
MathLib::Vector3 const b(p, r);
MathLib::Vector3 const c(p, s);
if (!GeoLib::isCoplanar(p, q, r, s))
{
double const denom = 2.0 * GeoLib::scalarTriple(a,b,c);
MathLib::Vector3 const o = (scalarProduct(c,c) * crossProduct(a,b)
+ scalarProduct(b,b) * crossProduct(c,a)
+ scalarProduct(a,a) * crossProduct(b,c))
* (1.0 / denom);
_radius = o.getLength() + std::numeric_limits<double>::epsilon();
_center = MathLib::Vector3(p) + o;
}
else
{
MinimalBoundingSphere const pqr(p, q , r);
MinimalBoundingSphere const pqs(p, q , s);
MinimalBoundingSphere const prs(p, r , s);
MinimalBoundingSphere const qrs(q, r , s);
_radius = pqr.getRadius();
_center = pqr.getCenter();
if (_radius < pqs.getRadius())
{
_radius = pqs.getRadius();
_center = pqs.getCenter();
}
if (_radius < prs.getRadius())
{
_radius = prs.getRadius();
_center = prs.getCenter();
}
if (_radius < qrs.getRadius())
{
_radius = qrs.getRadius();
_center = qrs.getCenter();
}
}
}