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Added IntersectionSegmentSphere

This commit is contained in:
Paolo Cignoni 2007-05-29 14:33:29 +00:00
parent 7b85798562
commit 1e2f4c1a80
1 changed files with 53 additions and 0 deletions
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53
vcg/space/intersection3.h
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@ -24,6 +24,9 @@
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$Log: not supported by cvs2svn $
Revision 1.31 2007/04/16 09:08:15 cignoni
commented out non compiling intersectionSpherePlane
Revision 1.30 2007/04/10 22:26:47 pietroni
IntersectionPlanePlane first parameter is a const
@ -179,6 +182,56 @@ namespace vcg {
return true;
}
/*
* Function computing the intersection between a sphere and a segment.
* @param[in] sphere the sphere
* @param[in] segment the segment
* @param[out] intersection the intersection point, meaningful only if the segment intersects the sphere
* \return (0, 1 or 2) the number of intersections between the segment and the sphere.
* t1 is a valid intersection only if the returned value is at least 1;
* similarly t2 is valid iff the returned value is 2.
*/
template < class SCALAR_TYPE >
inline int IntersectionSegmentSphere(const Sphere3<SCALAR_TYPE>& sphere, const Segment3<SCALAR_TYPE>& segment, Point3<SCALAR_TYPE> & t0, Point3<SCALAR_TYPE> & t1)
{
typedef SCALAR_TYPE ScalarType;
typedef typename vcg::Point3< ScalarType > Point3t;
Point3t s = segment.P0() - sphere.Center();
Point3t r = segment.P1() - segment.P0();
ScalarType rho2 = sphere.Radius()*sphere.Radius();
ScalarType sr = s*r;
ScalarType r_squared_norm = r.SquaredNorm();
ScalarType s_squared_norm = s.SquaredNorm();
ScalarType sigma = sr*sr - r_squared_norm*(s_squared_norm-rho2);
if (sigma<ScalarType(0.0)) // the line containing the edge doesn't intersect the sphere
return 0;
ScalarType sqrt_sigma = ScalarType(sqrt( ScalarType(sigma) ));
ScalarType lambda1 = (-sr - sqrt_sigma)/r_squared_norm;
ScalarType lambda2 = (-sr + sqrt_sigma)/r_squared_norm;
int solution_count = 0;
if (ScalarType(0.0)<=lambda1 && lambda1<=ScalarType(1.0))
{
ScalarType t_enter = vcg::math::Max< ScalarType >(lambda1, ScalarType(0.0));
t0 = segment.P0() + r*t_enter;
solution_count++;
}
if (ScalarType(0.0)<=lambda2 && lambda2<=ScalarType(1.0))
{
Point3t *pt = (solution_count>0) ? &t1 : &t0;
ScalarType t_exit = vcg::math::Min< ScalarType >(lambda2, ScalarType(1.0));
*pt = segment.P0() + r*t_exit;
solution_count++;
}
return solution_count;
}
/// intersection between line and plane
template<class T>
inline bool IntersectionLinePlane( const Plane3<T> & pl, const Line3<T> & li, Point3<T> & po){