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openmesh/Tools/Subdivider/Uniform/LoopT.hh
Jan Möbius 97f515985d First checkin for OpenMesh 2.0 
git-svn-id: http://www.openmesh.org/svnrepo/OpenMesh/trunk@2 fdac6126-5c0c-442c-9429-916003d36597
2009-02-06 13:37:46 +00:00

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//=============================================================================
//
// OpenMesh
// Copyright (C) 2003 by Computer Graphics Group, RWTH Aachen
// www.openmesh.org
//
//-----------------------------------------------------------------------------
//
// License
//
// 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, version 2.
//
// 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., 675 Mass Ave, Cambridge, MA 02139, USA.
//
//-----------------------------------------------------------------------------
//
// $Revision: 1802 $
// $Date: 2008-05-19 11:55:07 +0200 (Mo, 19. Mai 2008) $
//
//=============================================================================
/** \file LoopT.hh
*/
//=============================================================================
//
// CLASS LoopT
//
//=============================================================================
#ifndef OPENMESH_SUBDIVIDER_UNIFORM_LOOPT_HH
#define OPENMESH_SUBDIVIDER_UNIFORM_LOOPT_HH
//== INCLUDES =================================================================
#include <OpenMesh/Core/System/config.hh>
#include <OpenMesh/Tools/Subdivider/Uniform/SubdividerT.hh>
#include <OpenMesh/Core/Utils/vector_cast.hh>
// -------------------- STL
#include <vector>
#if defined(OM_CC_MIPS)
# include <math.h>
#else
# include <cmath>
#endif
//== NAMESPACE ================================================================
namespace OpenMesh { // BEGIN_NS_OPENMESH
namespace Subdivider { // BEGIN_NS_DECIMATER
namespace Uniform { // BEGIN_NS_DECIMATER
//== CLASS DEFINITION =========================================================
/** %Uniform Loop subdivision algorithm.
*
* Implementation as described in
*
* C. T. Loop, "Smooth Subdivision Surfaces Based on Triangles",
* M.S. Thesis, Department of Mathematics, University of Utah, August 1987.
*
*/
template <typename MeshType, typename RealType = float>
class LoopT : public SubdividerT<MeshType, RealType>
{
public:
typedef RealType real_t;
typedef MeshType mesh_t;
typedef SubdividerT< mesh_t, real_t > parent_t;
typedef std::pair< real_t, real_t > weight_t;
typedef std::vector< std::pair<real_t,real_t> > weights_t;
public:
LoopT(void) : parent_t(), _1over8( 1.0/8.0 ), _3over8( 3.0/8.0 )
{ init_weights(); }
LoopT( mesh_t& _m ) : parent_t(_m), _1over8( 1.0/8.0 ), _3over8( 3.0/8.0 )
{ init_weights(); }
~LoopT() {}
public:
const char *name() const { return "Uniform Loop"; }
/// Pre-compute weights
void init_weights(size_t _max_valence=50)
{
weights_.resize(_max_valence);
std::generate(weights_.begin(), weights_.end(), compute_weight());
}
protected:
bool prepare( mesh_t& _m )
{
_m.add_property( vp_pos_ );
_m.add_property( ep_pos_ );
return true;
}
bool cleanup( mesh_t& _m )
{
_m.remove_property( vp_pos_ );
_m.remove_property( ep_pos_ );
return true;
}
bool subdivide( mesh_t& _m, size_t _n)
{
typename mesh_t::FaceIter fit, f_end;
typename mesh_t::EdgeIter eit, e_end;
typename mesh_t::VertexIter vit;
// Do _n subdivisions
for (size_t i=0; i < _n; ++i)
{
// compute new positions for old vertices
for ( vit = _m.vertices_begin();
vit != _m.vertices_end(); ++vit)
smooth( _m, vit.handle() );
// Compute position for new vertices and store them in the edge property
for (eit=_m.edges_begin(); eit != _m.edges_end(); ++eit)
compute_midpoint( _m, eit.handle() );
// Split each edge at midpoint and store precomputed positions (stored in
// edge property ep_pos_) in the vertex property vp_pos_;
// Attention! Creating new edges, hence make sure the loop ends correctly.
e_end = _m.edges_end();
for (eit=_m.edges_begin(); eit != e_end; ++eit)
split_edge(_m, eit.handle() );
// Commit changes in topology and reconsitute consistency
// Attention! Creating new faces, hence make sure the loop ends correctly.
f_end = _m.faces_end();
for (fit = _m.faces_begin(); fit != f_end; ++fit)
split_face(_m, fit.handle() );
// Commit changes in geometry
for ( vit = _m.vertices_begin();
vit != _m.vertices_end(); ++vit)
_m.set_point(vit, _m.property( vp_pos_, vit ) );
#if defined(_DEBUG) || defined(DEBUG)
// Now we have an consistent mesh!
assert( OpenMesh::Utils::MeshCheckerT<mesh_t>(_m).check() );
#endif
}
return true;
}
private:
/// Helper functor to compute weights for Loop-subdivision
/// \internal
struct compute_weight
{
compute_weight() : valence(-1) { }
weight_t operator() (void)
{
#if !defined(OM_CC_MIPS)
using std::cos;
#endif
// 1
// alpha(n) = ---- * (40 - ( 3 + 2 cos( 2 Pi / n ) )<29> )
// 64
if (++valence)
{
double inv_v = 1.0/double(valence);
double t = (3.0 + 2.0 * cos( 2.0 * M_PI * inv_v) );
double alpha = (40.0 - t * t)/64.0;
return weight_t( 1.0-alpha, inv_v*alpha);
}
return weight_t(0.0, 0.0);
}
int valence;
};
private: // topological modifiers
void split_face(mesh_t& _m, const typename mesh_t::FaceHandle& _fh)
{
typename mesh_t::HalfedgeHandle
heh1(_m.halfedge_handle(_fh)),
heh2(_m.next_halfedge_handle(_m.next_halfedge_handle(heh1))),
heh3(_m.next_halfedge_handle(_m.next_halfedge_handle(heh2)));
// Cutting off every corner of the 6_gon
corner_cutting( _m, heh1 );
corner_cutting( _m, heh2 );
corner_cutting( _m, heh3 );
}
void corner_cutting(mesh_t& _m, const typename mesh_t::HalfedgeHandle& _he)
{
// Define Halfedge Handles
typename mesh_t::HalfedgeHandle
heh1(_he),
heh5(heh1),
heh6(_m.next_halfedge_handle(heh1));
// Cycle around the polygon to find correct Halfedge
for (; _m.next_halfedge_handle(_m.next_halfedge_handle(heh5)) != heh1;
heh5 = _m.next_halfedge_handle(heh5))
{}
typename mesh_t::VertexHandle
vh1 = _m.to_vertex_handle(heh1),
vh2 = _m.to_vertex_handle(heh5);
typename mesh_t::HalfedgeHandle
heh2(_m.next_halfedge_handle(heh5)),
heh3(_m.new_edge( vh1, vh2)),
heh4(_m.opposite_halfedge_handle(heh3));
/* Intermediate result
*
* *
* 5 /|\
* /_ \
* vh2> * *
* /|\3 |\
* /_ \|4 \
* *----\*----\*
* 1 ^ 6
* vh1 (adjust_outgoing halfedge!)
*/
// Old and new Face
typename mesh_t::FaceHandle fh_old(_m.face_handle(heh6));
typename mesh_t::FaceHandle fh_new(_m.new_face());
// Re-Set Handles around old Face
_m.set_next_halfedge_handle(heh4, heh6);
_m.set_next_halfedge_handle(heh5, heh4);
_m.set_face_handle(heh4, fh_old);
_m.set_face_handle(heh5, fh_old);
_m.set_face_handle(heh6, fh_old);
_m.set_halfedge_handle(fh_old, heh4);
// Re-Set Handles around new Face
_m.set_next_halfedge_handle(heh1, heh3);
_m.set_next_halfedge_handle(heh3, heh2);
_m.set_face_handle(heh1, fh_new);
_m.set_face_handle(heh2, fh_new);
_m.set_face_handle(heh3, fh_new);
_m.set_halfedge_handle(fh_new, heh1);
}
void split_edge(mesh_t& _m, const typename mesh_t::EdgeHandle& _eh)
{
typename mesh_t::HalfedgeHandle
heh = _m.halfedge_handle(_eh, 0),
opp_heh = _m.halfedge_handle(_eh, 1);
typename mesh_t::HalfedgeHandle new_heh, opp_new_heh, t_heh;
typename mesh_t::VertexHandle vh;
typename mesh_t::VertexHandle vh1(_m.to_vertex_handle(heh));
typename mesh_t::Point zero(0,0,0);
// new vertex
vh = _m.new_vertex( zero );
// memorize position, will be set later
_m.property( vp_pos_, vh ) = _m.property( ep_pos_, _eh );
// Re-link mesh entities
if (_m.is_boundary(_eh))
{
for (t_heh = heh;
_m.next_halfedge_handle(t_heh) != opp_heh;
t_heh = _m.opposite_halfedge_handle(_m.next_halfedge_handle(t_heh)))
{}
}
else
{
for (t_heh = _m.next_halfedge_handle(opp_heh);
_m.next_halfedge_handle(t_heh) != opp_heh;
t_heh = _m.next_halfedge_handle(t_heh) )
{}
}
new_heh = _m.new_edge(vh, vh1);
opp_new_heh = _m.opposite_halfedge_handle(new_heh);
_m.set_vertex_handle( heh, vh );
_m.set_next_halfedge_handle(t_heh, opp_new_heh);
_m.set_next_halfedge_handle(new_heh, _m.next_halfedge_handle(heh));
_m.set_next_halfedge_handle(heh, new_heh);
_m.set_next_halfedge_handle(opp_new_heh, opp_heh);
if (_m.face_handle(opp_heh).is_valid())
{
_m.set_face_handle(opp_new_heh, _m.face_handle(opp_heh));
_m.set_halfedge_handle(_m.face_handle(opp_new_heh), opp_new_heh);
}
_m.set_face_handle( new_heh, _m.face_handle(heh) );
_m.set_halfedge_handle( vh, new_heh);
_m.set_halfedge_handle( _m.face_handle(heh), heh );
_m.set_halfedge_handle( vh1, opp_new_heh );
// Never forget this, when playing with the topology
_m.adjust_outgoing_halfedge( vh );
_m.adjust_outgoing_halfedge( vh1 );
}
private: // geometry helper
void compute_midpoint(mesh_t& _m, const typename mesh_t::EdgeHandle& _eh)
{
#define V( X ) vector_cast< typename mesh_t::Normal >( X )
typename mesh_t::HalfedgeHandle heh, opp_heh;
heh = _m.halfedge_handle( _eh, 0);
opp_heh = _m.halfedge_handle( _eh, 1);
typename mesh_t::Point
pos(_m.point(_m.to_vertex_handle(heh)));
pos += V( _m.point(_m.to_vertex_handle(opp_heh)) );
// boundary edge: just average vertex positions
if (_m.is_boundary(_eh) )
{
pos *= 0.5;
}
else // inner edge: add neighbouring Vertices to sum
{
pos *= real_t(3.0);
pos += V(_m.point(_m.to_vertex_handle(_m.next_halfedge_handle(heh))));
pos += V(_m.point(_m.to_vertex_handle(_m.next_halfedge_handle(opp_heh))));
pos *= _1over8;
}
_m.property( ep_pos_, _eh ) = pos;
#undef V
}
void smooth(mesh_t& _m, const typename mesh_t::VertexHandle& _vh)
{
typename mesh_t::Point pos(0.0,0.0,0.0);
if (_m.is_boundary(_vh)) // if boundary: Point 1-6-1
{
typename mesh_t::HalfedgeHandle heh, prev_heh;
heh = _m.halfedge_handle( _vh );
if ( heh.is_valid() )
{
assert( _m.is_boundary( _m.edge_handle( heh ) ) );
prev_heh = _m.prev_halfedge_handle( heh );
typename mesh_t::VertexHandle
to_vh = _m.to_vertex_handle( heh ),
from_vh = _m.from_vertex_handle( prev_heh );
// ( v_l + 6 v + v_r ) / 8
pos = _m.point( _vh );
pos *= real_t(6.0);
pos += vector_cast< typename mesh_t::Normal >( _m.point( to_vh ) );
pos += vector_cast< typename mesh_t::Normal >( _m.point( from_vh ) );
pos *= _1over8;
}
else
return;
}
else // inner vertex: (1-a) * p + a/n * Sum q, q in one-ring of p
{
typedef typename mesh_t::Normal Vec;
typename mesh_t::VertexVertexIter vvit;
size_t valence(0);
// Calculate Valence and sum up neighbour points
for (vvit=_m.vv_iter(_vh); vvit; ++vvit) {
++valence;
pos += vector_cast< Vec >( _m.point(vvit) );
}
pos *= weights_[valence].second; // alpha(n)/n * Sum q, q in one-ring of p
pos += weights_[valence].first
* vector_cast<Vec>(_m.point(_vh)); // + (1-a)*p
}
_m.property( vp_pos_, _vh ) = pos;
}
private: // data
OpenMesh::VPropHandleT< typename mesh_t::Point > vp_pos_;
OpenMesh::EPropHandleT< typename mesh_t::Point > ep_pos_;
weights_t weights_;
const real_t _1over8;
const real_t _3over8;
};
//=============================================================================
} // END_NS_UNIFORM
} // END_NS_SUBDIVIDER
} // END_NS_OPENMESH
//=============================================================================
#endif // OPENMESH_SUBDIVIDER_UNIFORM_COMPOSITELOOPT_HH defined
//=============================================================================
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