ModifiedButterFlyT.hh
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//=============================================================================
//
// CLASS ModifiedButterflyT
//
//=============================================================================
#ifndef SP_MODIFIED_BUTTERFLY_H
#define SP_MODIFIED_BUTTERFLY_H
#include <OpenMesh/Tools/Subdivider/Uniform/SubdividerT.hh>
#include <OpenMesh/Core/Utils/vector_cast.hh>
#include <OpenMesh/Core/Utils/Property.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_UNIFORM
//== CLASS DEFINITION =========================================================
template <typename MeshType, typename RealType = double>
class ModifiedButterflyT : public SubdividerT<MeshType, RealType>
{
public:
typedef RealType real_t;
typedef MeshType mesh_t;
typedef SubdividerT< mesh_t, real_t > parent_t;
typedef std::vector< std::vector<real_t> > weights_t;
typedef std::vector<real_t> weight_t;
public:
ModifiedButterflyT() : parent_t()
{ init_weights(); }
ModifiedButterflyT( mesh_t& _m) : parent_t(_m)
{ init_weights(); }
~ModifiedButterflyT() {}
public:
const char *name() const { return "Uniform Spectral"; }
void init_weights(size_t _max_valence=30)
{
weights.resize(_max_valence);
//special case: K==3, K==4
weights[3].resize(4);
weights[3][0] = real_t(5.0)/12;
weights[3][1] = real_t(-1.0)/12;
weights[3][2] = real_t(-1.0)/12;
weights[3][3] = real_t(3.0)/4;
weights[4].resize(5);
weights[4][0] = real_t(3.0)/8;
weights[4][1] = 0;
weights[4][2] = real_t(-1.0)/8;
weights[4][3] = 0;
weights[4][4] = real_t(3.0)/4;
for(unsigned int K = 5; K<_max_valence; ++K)
{
weights[K].resize(K+1);
// s(j) = ( 1/4 + cos(2*pi*j/K) + 1/2 * cos(4*pi*j/K) )/K
double invK = 1.0/static_cast<double>(K);
real_t sum = 0;
for(unsigned int j=0; j<K; ++j)
{
weights[K][j] = static_cast<real_t>((0.25 + cos(2.0*M_PI*static_cast<double>(j)*invK) + 0.5*cos(4.0*M_PI*static_cast<double>(j)*invK))*invK);
sum += weights[K][j];
}
weights[K][K] = static_cast<real_t>(1.0) - sum;
}
}
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( MeshType& _m, size_t _n , const bool _update_points = true)
{
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)
{
// This is an interpolating scheme, old vertices remain the same.
typename mesh_t::VertexIter initialVerticesEnd = _m.vertices_end();
for ( vit = _m.vertices_begin(); vit != initialVerticesEnd; ++vit)
_m.property( vp_pos_, *vit ) = _m.point(*vit);
// 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 );
// 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 );
// 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 );
// Commit changes in geometry
for ( vit = /*initialVerticesEnd;*/_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: // 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)
{
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(0,0,0);
typename mesh_t::VertexHandle a_0(_m.to_vertex_handle(heh));
typename mesh_t::VertexHandle a_1(_m.to_vertex_handle(opp_heh));
// boundary edge: 4-point scheme
if (_m.is_boundary(_eh) )
{
pos = _m.point(a_0);
pos += _m.point(a_1);
pos *= static_cast<typename mesh_t::Point::value_type>(9.0/16.0);
typename mesh_t::Point tpos;
if(_m.is_boundary(heh))
{
tpos = _m.point(_m.to_vertex_handle(_m.next_halfedge_handle(heh)));
tpos += _m.point(_m.to_vertex_handle(_m.opposite_halfedge_handle(_m.prev_halfedge_handle(heh))));
}
else
{
assert(_m.is_boundary(opp_heh));
tpos = _m.point(_m.to_vertex_handle(_m.next_halfedge_handle(opp_heh)));
tpos += _m.point(_m.to_vertex_handle(_m.opposite_halfedge_handle(_m.prev_halfedge_handle(opp_heh))));
}
tpos *= static_cast<typename mesh_t::Point::value_type>(-1.0/16.0);
pos += tpos;
}
else
{
int valence_a_0 = _m.valence(a_0);
int valence_a_1 = _m.valence(a_1);
assert(valence_a_0>2);
assert(valence_a_1>2);
if( (valence_a_0==6 && valence_a_1==6) || (_m.is_boundary(a_0) && valence_a_1==6) || (_m.is_boundary(a_1) && valence_a_0==6) || (_m.is_boundary(a_0) && _m.is_boundary(a_1)) )// use 8-point scheme
{
real_t alpha = real_t(1.0/2);
real_t beta = real_t(1.0/8);
real_t gamma = real_t(-1.0/16);
//get points
typename mesh_t::VertexHandle b_0, b_1, c_0, c_1, c_2, c_3;
typename mesh_t::HalfedgeHandle t_he;
t_he = _m.next_halfedge_handle(_m.opposite_halfedge_handle(heh));
b_0 = _m.to_vertex_handle(t_he);
if(!_m.is_boundary(_m.opposite_halfedge_handle(t_he)))
{
t_he = _m.next_halfedge_handle(_m.opposite_halfedge_handle(t_he));
c_0 = _m.to_vertex_handle(t_he);
}
t_he = _m.opposite_halfedge_handle(_m.prev_halfedge_handle(heh));
b_1 = _m.to_vertex_handle(t_he);
if(!_m.is_boundary(t_he))
{
t_he = _m.opposite_halfedge_handle(_m.prev_halfedge_handle(t_he));
c_1 = _m.to_vertex_handle(t_he);
}
t_he = _m.next_halfedge_handle(_m.opposite_halfedge_handle(opp_heh));
assert(b_1.idx()==_m.to_vertex_handle(t_he).idx());
if(!_m.is_boundary(_m.opposite_halfedge_handle(t_he)))
{
t_he = _m.next_halfedge_handle(_m.opposite_halfedge_handle(t_he));
c_2 = _m.to_vertex_handle(t_he);
}
t_he = _m.opposite_halfedge_handle(_m.prev_halfedge_handle(opp_heh));
assert(b_0==_m.to_vertex_handle(t_he));
if(!_m.is_boundary(t_he))
{
t_he = _m.opposite_halfedge_handle(_m.prev_halfedge_handle(t_he));
c_3 = _m.to_vertex_handle(t_he);
}
//compute position.
//a0,a1,b0,b1 must exist.
assert(a_0.is_valid());
assert(a_1.is_valid());
assert(b_0.is_valid());
assert(b_1.is_valid());
//The other vertices may be created from symmetry is they are on the other side of the boundary.
pos = _m.point(a_0);
pos += _m.point(a_1);
pos *= alpha;
typename mesh_t::Point tpos ( _m.point(b_0) );
tpos += _m.point(b_1);
tpos *= beta;
pos += tpos;
typename mesh_t::Point pc_0, pc_1, pc_2, pc_3;
if(c_0.is_valid())
pc_0 = _m.point(c_0);
else //create the point by symmetry
{
pc_0 = _m.point(a_1) + _m.point(b_0) - _m.point(a_0);
}
if(c_1.is_valid())
pc_1 = _m.point(c_1);
else //create the point by symmetry
{
pc_1 = _m.point(a_1) + _m.point(b_1) - _m.point(a_0);
}
if(c_2.is_valid())
pc_2 = _m.point(c_2);
else //create the point by symmetry
{
pc_2 = _m.point(a_0) + _m.point(b_1) - _m.point(a_1);
}
if(c_3.is_valid())
pc_3 = _m.point(c_3);
else //create the point by symmetry
{
pc_3 = _m.point(a_0) + _m.point(b_0) - _m.point(a_1);
}
tpos = pc_0;
tpos += pc_1;
tpos += pc_2;
tpos += pc_3;
tpos *= gamma;
pos += tpos;
}
else //at least one endpoint is [irregular and not in boundary]
{
typename mesh_t::Point::value_type normFactor = static_cast<typename mesh_t::Point::value_type>(0.0);
if(valence_a_0!=6 && !_m.is_boundary(a_0))
{
assert((int)weights[valence_a_0].size()==valence_a_0+1);
typename mesh_t::HalfedgeHandle t_he = opp_heh;
for(int i = 0; i < valence_a_0 ; t_he=_m.next_halfedge_handle(_m.opposite_halfedge_handle(t_he)), ++i)
{
pos += weights[valence_a_0][i] * _m.point(_m.to_vertex_handle(t_he));
}
assert(t_he==opp_heh);
//add irregular vertex:
pos += weights[valence_a_0][valence_a_0] * _m.point(a_0);
++normFactor;
}
if(valence_a_1!=6 && !_m.is_boundary(a_1))
{
assert((int)weights[valence_a_1].size()==valence_a_1+1);
typename mesh_t::HalfedgeHandle t_he = heh;
for(int i = 0; i < valence_a_1 ; t_he=_m.next_halfedge_handle(_m.opposite_halfedge_handle(t_he)), ++i)
{
pos += weights[valence_a_1][i] * _m.point(_m.to_vertex_handle(t_he));
}
assert(t_he==heh);
//add irregular vertex:
pos += weights[valence_a_1][valence_a_1] * _m.point(a_1);
++normFactor;
}
assert(normFactor>0.1); //normFactor should be 1 or 2
//if both vertices are irregular, average positions:
pos /= normFactor;
}
}
_m.property( ep_pos_, _eh ) = pos;
}
private: // data
OpenMesh::VPropHandleT< typename mesh_t::Point > vp_pos_;
OpenMesh::EPropHandleT< typename mesh_t::Point > ep_pos_;
weights_t weights;
};
} // END_NS_UNIFORM
} // END_NS_SUBDIVIDER
} // END_NS_OPENMESH
#endif
OpenMesh::Subdivider::Uniform::SubdividerT
Abstract base class for uniform subdivision algorithms.
Definition: SubdividerT.hh:93
OpenMesh::Subdivider::Uniform::ModifiedButterflyT::prepare
bool prepare(mesh_t &_m)
Prepare mesh, e.g. add properties.
Definition: ModifiedButterFlyT.hh:168
OpenMesh::PolyMeshT::VertexHandle
Kernel::VertexHandle VertexHandle
Handle for referencing the corresponding item.
Definition: PolyMeshT.hh:139
OpenMesh::Utils::MeshCheckerT
Check integrity of mesh.
Definition: MeshCheckerT.hh:78
OpenMesh::Subdivider::Uniform::ModifiedButterflyT::cleanup
bool cleanup(mesh_t &_m)
Cleanup mesh after usage, e.g. remove added properties.
Definition: ModifiedButterFlyT.hh:176
OpenMesh
Contains all the mesh ingredients like the polygonal mesh, the triangle mesh, different mesh kernels ...
Definition: MeshItems.hh:64
SubdividerT.hh
OpenMesh::Subdivider::Uniform::ModifiedButterflyT::name
const char * name() const
Return name of subdivision algorithm.
Definition: ModifiedButterFlyT.hh:127
OpenMesh::VPropHandleT< typename mesh_t::Point >
OpenMesh::EPropHandleT< typename mesh_t::Point >
OpenMesh::Subdivider::Uniform::ModifiedButterflyT
Modified Butterfly subdivision algorithm.
Definition: ModifiedButterFlyT.hh:99
OpenMesh::Subdivider::Uniform::ModifiedButterflyT::subdivide
bool subdivide(MeshType &_m, size_t _n, const bool _update_points=true)
Subdivide mesh _m _n times.
Definition: ModifiedButterFlyT.hh:184
OpenMesh::Subdivider::Uniform::ModifiedButterflyT::init_weights
void init_weights(size_t _max_valence=30)
Pre-compute weights.
Definition: ModifiedButterFlyT.hh:131