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Newer version.

This commit is contained in:
Ron Wein 2003-09-03 13:09:12 +00:00
parent 4db5eaee05
commit f4d7c97af2
1 changed files with 68 additions and 10 deletions
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78
Packages/Arrangement/include/CGAL/Arrangement_2/Hyper_segment_2.h
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@ -56,19 +56,21 @@ public:
private:
NT _A; // The coefficients of the equation of
NT _B; // the underlying canonical hyperbola:
NT _C; // y = sqrt (A*x^2 + B*x + C)
bool _is_seg; // Is this hyper-segment actaully a line segment.
NT _A; // The coefficients of the equation of
NT _B; // the underlying canonical hyperbola:
NT _C; // y = sqrt (A*x^2 + B*x + C)
Point_2 _source; // The hyperbolic segment source.
Point_2 _target; // The hyperbolic segment target.
Point_2 _source; // The hyperbolic segment source.
Point_2 _target; // The hyperbolic segment target.
public:
/*!
* Default constructor.
*/
Hyper_segment_2 ()
Hyper_segment_2 () :
_is_seg(true)
{}
/*!
@ -85,10 +87,10 @@ private:
* Furthermore, x_max > x_min.
*/
Hyper_segment_2 (const NT& a, const NT& b, const NT& c, const NT& d,
const NT& x_min, const NT& x_max)
const NT& x_min, const NT& x_max) :
_is_seg(false)
{
static const NT _zero = 0;
CGAL_precondition_code (static const NT _zero = 0;);
CGAL_precondition(_compare (a, _zero) == LARGER);
CGAL_precondition(_compare (b, _zero) == SMALLER);
CGAL_precondition(_compare (x_min, x_max) == SMALLER);
@ -130,6 +132,53 @@ private:
*/
}
/*!
* Construct a degenerate hyperbolic segment defined by a line segment.
* \param ps The source point of the segment.
* \param pt The target point of the segment.
* \pre The segment is not vertical -- that is, x(ps) does not equal x(pt).
* Furthermore, both points should lie above the x-axis.
*/
Hyper_segment_2 (const Point_2& ps, const Point_2& pt) :
_is_seg(true)
{
// Make sure that the two points do not define a vertical segment.
Comparison_result comp_x = _compare (ps.x(), pt.x());
CGAL_precondition(comp_x != EQUAL);
// Make sure that both points are above the x-axis.
CGAL_precondition_code (static const NT _zero = 0;);
CGAL_precondition(_compare (ps.y(), _zero) == LARGER);
CGAL_precondition(_compare (pt.y(), _zero) == LARGER);
// Find the line (y = a*x + b) that connects the two points.
const NT denom = ps.x() - pt.x();
const NT a = (ps.y() - pt.y()) / denom;
const NT b = (ps.x()*pt.y() - pt.x()*ps.y()) / denom;
// Set the underlying hyperbola to be the pair of lines:
// y^2 = (a*x + b)^2 = (a^2)*x^2 + (2ab)*x + b^2
_A = a*a;
_B = 2*a*b;
_C = b*b;
// Set the source and target point.
if (comp_x == SMALLER)
{
_source = ps;
_target = pt;
}
else
{
_source = pt;
_target = ps;
}
}
/*!
* Access the hyperblic coeffcients.
*/
const NT& A () const {return (_A);}
const NT& B () const {return (_B);}
const NT& C () const {return (_C);}
@ -152,6 +201,15 @@ private:
return (_target);
}
/*!
* Check whether the hyper-segment is actually a line segment.
* \return (true) if the underlying hyperbola is actually a line segment.
*/
bool is_linear () const
{
return (_is_seg);
}
/*!
* Check if the two hyper-segments are equal.
* \param seg The compares hyper-segments.
@ -548,7 +606,7 @@ protected:
*/
inline Comparison_result _compare (const NT& val1, const NT& val2) const
{
return (CGAL::compare(val1, val2));
return (CGAL_NTS compare(val1, val2));
}
/*!