ON_PeriodicDomain Class Reference

#include <opennurbs_point.h>

Public Member Functions
	ON_PeriodicDomain ()=default
	ON_PeriodicDomain (const ON_Interval dom[2], const bool closed[2], double normband=1.0/3.0)
void	Initialize (const ON_Interval dom[2], const bool closed[2], double normband=1.0/3.0)
ON_2dPoint	LiftInverse (ON_2dPoint p)
	The projection from covering space back to domain. LiftInverse(LiftToCover(p))==p. More...
ON_2dPoint	LiftToCover (ON_2dPoint Pin, bool stealth=false)

Public Attributes
bool	m_closed [2] = {}
ON_Interval	m_dom [2]
double	m_normband = ON_DBL_QNAN

Detailed Description

ON_PeriodicDomain is a helper class for dealing with closed or periodic surfaces using the idea of a covering space.

If a surface is closed in the u-direction (or v respectively), a curve on the surface that crosses the seam will not have a continuous pull back to parameter space. However, if we extend the surface domain in the u-coordinates and allow the surface to cover itself periodicly, i.e S(u,v) = S(u + T, v) with period T, then we can pull back the curve to the domain covering space (-inf,inf) x dom[1].

Constructor & Destructor Documentation

ON_PeriodicDomain() [1/2]

ON_PeriodicDomain::ON_PeriodicDomain ( )

default

ON_PeriodicDomain() [2/2]

ON_PeriodicDomain::ON_PeriodicDomain	(	const ON_Interval	dom[2],
		const bool	closed[2],
		double	normband = 1.0/3.0
	)

Member Function Documentation

Initialize()

void ON_PeriodicDomain::Initialize	(	const ON_Interval	dom[2],
		const bool	closed[2],
		double	normband = 1.0/3.0
	)

LiftInverse()

ON_2dPoint ON_PeriodicDomain::LiftInverse

(

ON_2dPoint

p

)

The projection from covering space back to domain. LiftInverse(LiftToCover(p))==p.

LiftToCover()

ON_2dPoint ON_PeriodicDomain::LiftToCover	(	ON_2dPoint	Pin,
		bool	stealth = false
	)

Construction or Initialization Parameters: dom -[in] surface domain closed -[in] closed[0] is true if the surface is closed in u direction (similarly for 1 and v) Use ON_IsG1Closed(...) to test for G1-closed surfaces. normband - [in] 0<normband<.5 is a normalized coordinate defining a band on each side of the seam. The bands are {(u,v): dom[0].NormalizedParameterAt(u)< normband } and {(u,v): dom[0].NormalizedParameterAt(u)> 1.0 - normband } The point sequence crosses the seam if consecutive points are in opposite bands along the seam. Repeatedly call LiftToCover( Pin) with Pin in the domain covering space. The resulting output sequence will be lifted to the domain covering space, and will be 'continuous' in that consecutive points will be in the same or an adjacent band. Use stealth=true to lift this point without affecting the state, this allows one to compute a trial end of sequence.
see also ON_LiftToCover(...).

Member Data Documentation

m_closed

bool ON_PeriodicDomain::m_closed[2] = {}

m_dom

ON_Interval ON_PeriodicDomain::m_dom[2]

m_normband

double ON_PeriodicDomain::m_normband = ON_DBL_QNAN