geometryApproximator.hpp 10.2 KB
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/*******************************************************************************
* CGoGN: Combinatorial and Geometric modeling with Generic N-dimensional Maps  *
* version 0.1                                                                  *
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* Copyright (C) 2009-2012, IGG Team, LSIIT, University of Strasbourg           *
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*                                                                              *
* This library is free software; you can redistribute it and/or modify it      *
* under the terms of the GNU Lesser General Public License as published by the *
* Free Software Foundation; either version 2.1 of the License, or (at your     *
* option) any later version.                                                   *
*                                                                              *
* This library is distributed in the hope that it will be useful, but WITHOUT  *
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or        *
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License  *
* for more details.                                                            *
*                                                                              *
* You should have received a copy of the GNU Lesser General Public License     *
* along with this library; if not, write to the Free Software Foundation,      *
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA.           *
*                                                                              *
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* Web site: http://cgogn.unistra.fr/                                           *
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* Contact information: cgogn@unistra.fr                                        *
*                                                                              *
*******************************************************************************/

namespace CGoGN
{

namespace Algo
{

namespace Decimation
{

/************************************************************************************
 *                            QUADRIC ERROR METRIC                                  *
 ************************************************************************************/

template <typename PFP>
bool Approximator_QEM<PFP>::init()
{
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	m_quadric = this->m_map.template getAttribute<Quadric<REAL> >(VERTEX, "QEMquadric") ;
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	if(this->m_predictor)
	{
		return false ;
	}
	return true ;
}

template <typename PFP>
void Approximator_QEM<PFP>::approximate(Dart d)
{
	MAP& m = this->m_map ;

	// get some darts
	Dart dd = m.phi2(d) ;

	Quadric<REAL> q1, q2 ;
	if(!m_quadric.isValid()) // if the selector is not QEM, compute local error quadrics
	{
		// compute the error quadric associated to v1
		Dart it = d ;
		do
		{
			Quadric<REAL> q(this->m_attrV[it], this->m_attrV[m.phi1(it)], this->m_attrV[m.phi_1(it)]) ;
			q1 += q ;
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			it = m.phi2_1(it) ;
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		} while(it != d) ;

		// compute the error quadric associated to v2
		it = dd ;
		do
		{
			Quadric<REAL> q(this->m_attrV[it], this->m_attrV[m.phi1(it)], this->m_attrV[m.phi_1(it)]) ;
			q2 += q ;
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			it = m.phi2_1(it) ;
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		} while(it != dd) ;
	}
	else // if the selector is QEM, use the error quadrics computed by the selector
	{
		q1 = m_quadric[d] ;
		q2 = m_quadric[dd] ;
	}

	Quadric<REAL> quad ;
	quad += q1 ;	// compute the sum of the
	quad += q2 ;	// two vertices quadrics

	VEC3 res ;
	bool opt = quad.findOptimizedPos(res) ;	// try to compute an optimized position for the contraction of this edge
	if(!opt)
	{
		VEC3 p1 = this->m_attrV[d] ;	// let the new vertex lie
		VEC3 p2 = this->m_attrV[dd] ;	// on either one of the two endpoints
		VEC3 p12 = (p1 + p2) / 2.0f ;	// or the middle of the edge
		REAL e1 = quad(p1) ;
		REAL e2 = quad(p2) ;
		REAL e12 = quad(p12) ;
		REAL minerr = std::min(std::min(e1, e2), e12) ;	// consider only the one for
		if(minerr == e12) this->m_approx[d] = p12 ;		// which the error is minimal
		else if(minerr == e1) this->m_approx[d] = p1 ;
		else this->m_approx[d] = p2 ;
	}
	else
		this->m_approx[d] = res ;
}

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/************************************************************************************
 *                            QUADRIC ERROR METRIC (for half-edge criteria)         *
 ************************************************************************************/

template <typename PFP>
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bool Approximator_QEMhalfEdge<PFP>::init()
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{
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	m_quadric = this->m_map.template getAttribute<Quadric<REAL> >(VERTEX, "QEMquadric") ;
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	if(this->m_predictor)
	{
		return false ;
	}
	return true ;
}

template <typename PFP>
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void Approximator_QEMhalfEdge<PFP>::approximate(Dart d)
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{
	MAP& m = this->m_map ;

	// get some darts
	Dart dd = m.phi2(d) ;

	Quadric<REAL> q1, q2 ;
	if(!m_quadric.isValid()) // if the selector is not QEM, compute local error quadrics
	{
		// compute the error quadric associated to v1
		Dart it = d ;
		do
		{
			Quadric<REAL> q(this->m_attrV[it], this->m_attrV[m.phi1(it)], this->m_attrV[m.phi_1(it)]) ;
			q1 += q ;
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			it = m.phi2_1(it) ;
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		} while(it != d) ;

		// compute the error quadric associated to v2
		it = dd ;
		do
		{
			Quadric<REAL> q(this->m_attrV[it], this->m_attrV[m.phi1(it)], this->m_attrV[m.phi_1(it)]) ;
			q2 += q ;
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			it = m.phi2_1(it) ;
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		} while(it != dd) ;
	}
	else // if the selector is QEM, use the error quadrics computed by the selector
	{
		q1 = m_quadric[d] ;
		q2 = m_quadric[dd] ;
	}

	Quadric<REAL> quad ;
	quad += q1 ;	// compute the sum of the
	quad += q2 ;	// two vertices quadrics

	VEC3 res ;
	bool opt = quad.findOptimizedPos(res) ;	// try to compute an optimized position for the contraction of this edge
	if(!opt)
		this->m_approx[d] = this->m_attrV[d] ;
	else
		this->m_approx[d] = res ;
}

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/************************************************************************************
 *							         MID EDGE                                       *
 ************************************************************************************/

template <typename PFP>
bool Approximator_MidEdge<PFP>::init()
{
	if(this->m_predictor)
	{
		if(! (	this->m_predictor->getType() == P_TangentPredict1
			 || this->m_predictor->getType() == P_TangentPredict2 ) )
		{
			return false ;
		}
	}
	return true ;
}

template <typename PFP>
void Approximator_MidEdge<PFP>::approximate(Dart d)
{
	MAP& m = this->m_map ;

	// get some darts
	Dart dd = m.phi2(d) ;

	// get the contracted edge vertices positions
	VEC3 v1 = this->m_attrV[d] ;
	VEC3 v2 = this->m_attrV[dd] ;

	// Compute the approximated position
	this->m_approx[d] = (v1 + v2) / REAL(2) ;

	if(this->m_predictor)
	{
		Dart dd = m.phi2(d) ;
		Dart d2 = m.phi2(m.phi_1(d)) ;
		Dart dd2 = m.phi2(m.phi_1(dd)) ;

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		// VEC3 v2 = this->m_attrV[dd] ;
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		// temporary edge collapse
		m.extractTrianglePair(d) ;
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		unsigned int newV = m.embedNewCell(VERTEX, d2) ;
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		this->m_attrV[newV] = this->m_approx[d] ;

		// compute the detail vector
		this->m_predictor->predict(d2, dd2) ;
		this->m_detail[d] = v1 - this->m_predictor->getPredict(0) ;

		// vertex split to reset the initial connectivity and embeddings
		m.insertTrianglePair(d, d2, dd2) ;
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		m.embedOrbit(VERTEX, d, m.getEmbedding(VERTEX, d)) ;
		m.embedOrbit(VERTEX, dd, m.getEmbedding(VERTEX, dd)) ;
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	}
}

/************************************************************************************
 *							       HALF COLLAPSE                                    *
 ************************************************************************************/

template <typename PFP>
bool Approximator_HalfCollapse<PFP>::init()
{
	if(this->m_predictor)
	{
		if(! ( this->m_predictor->getType() == P_HalfCollapse ) )
		{
			return false ;
		}
	}
	return true ;
}

template <typename PFP>
void Approximator_HalfCollapse<PFP>::approximate(Dart d)
{
	MAP& m = this->m_map ;

	this->m_approx[d] = this->m_attrV[d] ;

	if(this->m_predictor)
	{
		Dart dd = m.phi2(d) ;
		Dart d2 = m.phi2(m.phi_1(d)) ;
		Dart dd2 = m.phi2(m.phi_1(dd)) ;

		VEC3 v2 = this->m_attrV[dd] ;

		// temporary edge collapse
		m.extractTrianglePair(d) ;
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		unsigned int newV = m.embedNewCell(VERTEX, d2) ;
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		this->m_attrV[newV] = this->m_approx[d] ;

		// compute the detail vector
		this->m_predictor->predict(d2, dd2) ;
		this->m_detail[d] = v2 - this->m_predictor->getPredict(1) ;

		// vertex split to reset the initial connectivity and embeddings
		m.insertTrianglePair(d, d2, dd2) ;
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		m.embedOrbit(VERTEX, d, m.getEmbedding(VERTEX, d)) ;
		m.embedOrbit(VERTEX, dd, m.getEmbedding(VERTEX, dd)) ;
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	}
}

/************************************************************************************
 *							      CORNER CUTTING                                    *
 ************************************************************************************/

template <typename PFP>
bool Approximator_CornerCutting<PFP>::init()
{
	if(this->m_predictor)
	{
		if(! ( this->m_predictor->getType() == P_CornerCutting ) )
		{
			return false ;
		}
	}
	return true ;
}

template <typename PFP>
void Approximator_CornerCutting<PFP>::approximate(Dart d)
{
	MAP& m = this->m_map ;

	// get some darts
	Dart dd = m.phi2(d) ;
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	// Dart d1 = m.phi2(m.phi1(d)) ;
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	Dart d2 = m.phi2(m.phi_1(d)) ;
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	// Dart dd1 = m.phi2(m.phi1(dd)) ;
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	Dart dd2 = m.phi2(m.phi_1(dd)) ;

	// get the contracted edge vertices positions
	VEC3 v1 = this->m_attrV[d] ;
	VEC3 v2 = this->m_attrV[dd] ;

	// compute the alpha value according to vertices valences
	REAL k1 = 0 ;
	Dart it = d ;
	do
	{
		++k1 ;
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		it = m.phi2_1(it) ;
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	} while(it != d) ;
	REAL k2 = 0 ;
	it = dd ;
	do
	{
		++k2 ;
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		it = m.phi2_1(it) ;
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	} while(it != dd) ;
	REAL alpha = (k1-1) * (k2-1) / (k1*k2-1) ;

	// Compute the mean of v1 half-ring
	VEC3 m1(0) ;
	unsigned int count = 0 ;
	it = d2 ;
	do
	{
		m1 += this->m_attrV[m.phi1(it)] ;
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		it = m.phi2_1(it) ;
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		++count ;
	} while (it != d) ;
	m1 /= REAL(count) ;

	// Compute the mean of v2 half-ring
	VEC3 m2(0) ;
	count = 0 ;
	it = dd2 ;
	do
	{
		m2 += this->m_attrV[m.phi1(it)] ;
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		it = m.phi2_1(it) ;
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		++count ;
	} while (it != dd) ;
	m2 /= REAL(count) ;

	// Compute the a1 approximation
	VEC3 a1 = ( REAL(1) / (REAL(1) - alpha) ) * ( v1 - (alpha * m1) ) ;
	// Compute the a2 approximation
	VEC3 a2 = ( REAL(1) / (REAL(1) - alpha) ) * ( v2 - (alpha * m2) ) ;

	// Compute the final approximated position
	this->m_approx[d] = (a1 + a2) / REAL(2) ;

	if(this->m_predictor)
	{
		this->m_detail[d] = (REAL(1) - alpha) * ( (a1 - a2) / REAL(2) ) ;
	}
}

} //namespace Decimation

} //namespace Algo

} //namespace CGoGN