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LoopT.hh
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48
53 //=============================================================================
54 //
55 // CLASS LoopT
56 //
57 //=============================================================================
58
59 #ifndef OPENMESH_SUBDIVIDER_UNIFORM_LOOPT_HH
60 #define OPENMESH_SUBDIVIDER_UNIFORM_LOOPT_HH
61
62
63 //== INCLUDES =================================================================
64
65 #include <OpenMesh/Core/System/config.hh>
66 #include <OpenMesh/Tools/Subdivider/Uniform/SubdividerT.hh>
67 #include <OpenMesh/Core/Utils/vector_cast.hh>
68 #include <OpenMesh/Core/Utils/Property.hh>
69 // -------------------- STL
70 #include <vector>
71 #if defined(OM_CC_MIPS)
72 # include <math.h>
73 #else
74 # include <cmath>
75 #endif
76
77
78 //== NAMESPACE ================================================================
79
80 namespace OpenMesh { // BEGIN_NS_OPENMESH
81 namespace Subdivider { // BEGIN_NS_DECIMATER
82 namespace Uniform { // BEGIN_NS_DECIMATER
83
84
85 //== CLASS DEFINITION =========================================================
86
95 template <typename MeshType, typename RealType = float>
96 class LoopT : public SubdividerT<MeshType, RealType>
97 {
98 public:
99
100 typedef RealType real_t;
101 typedef MeshType mesh_t;
102 typedef SubdividerT< mesh_t, real_t > parent_t;
103
104 typedef std::pair< real_t, real_t > weight_t;
105 typedef std::vector< std::pair<real_t,real_t> > weights_t;
106
107 public:
108
109
110 LoopT(void) : parent_t(), _1over8( 1.0/8.0 ), _3over8( 3.0/8.0 )
111 { init_weights(); }
112
113
114 LoopT( mesh_t& _m ) : parent_t(_m), _1over8( 1.0/8.0 ), _3over8( 3.0/8.0 )
115 { init_weights(); }
116
117
118 ~LoopT() {}
119
120
121 public:
122
123
124 const char *name() const { return "Uniform Loop"; }
125
126
128 void init_weights(size_t _max_valence=50)
129 {
130 weights_.resize(_max_valence);
131 std::generate(weights_.begin(), weights_.end(), compute_weight());
132 }
133
134
135 protected:
136
137
138 bool prepare( mesh_t& _m )
139 {
140 _m.add_property( vp_pos_ );
141 _m.add_property( ep_pos_ );
142 return true;
143 }
144
145
146 bool cleanup( mesh_t& _m )
147 {
148 _m.remove_property( vp_pos_ );
149 _m.remove_property( ep_pos_ );
150 return true;
151 }
152
153
154 bool subdivide( mesh_t& _m, size_t _n, const bool _update_points = true)
155 {
156
158
159 typename mesh_t::FaceIter fit, f_end;
160 typename mesh_t::EdgeIter eit, e_end;
161 typename mesh_t::VertexIter vit;
162
163 // Do _n subdivisions
164 for (size_t i=0; i < _n; ++i)
165 {
166
167 if(_update_points) {
168 // compute new positions for old vertices
169 for (vit = _m.vertices_begin(); vit != _m.vertices_end(); ++vit) {
170 smooth(_m, *vit);
171 }
172 }
173
174 // Compute position for new vertices and store them in the edge property
175 for (eit=_m.edges_begin(); eit != _m.edges_end(); ++eit)
176 compute_midpoint( _m, *eit );
177
178 // Split each edge at midpoint and store precomputed positions (stored in
179 // edge property ep_pos_) in the vertex property vp_pos_;
180
181 // Attention! Creating new edges, hence make sure the loop ends correctly.
182 e_end = _m.edges_end();
183 for (eit=_m.edges_begin(); eit != e_end; ++eit)
184 split_edge(_m, *eit );
185
186
187 // Commit changes in topology and reconsitute consistency
188
189 // Attention! Creating new faces, hence make sure the loop ends correctly.
190 f_end = _m.faces_end();
191 for (fit = _m.faces_begin(); fit != f_end; ++fit)
192 split_face(_m, *fit );
193
194 if(_update_points) {
195 // Commit changes in geometry
196 for ( vit = _m.vertices_begin();
197 vit != _m.vertices_end(); ++vit) {
198 _m.set_point(*vit, _m.property( vp_pos_, *vit ) );
199 }
200 }
201
202
203 #if defined(_DEBUG) || defined(DEBUG)
204 // Now we have an consistent mesh!
205 assert( OpenMesh::Utils::MeshCheckerT<mesh_t>(_m).check() );
206 #endif
207 }
208
209 return true;
210 }
211
212 private:
213
216 struct compute_weight
217 {
218 compute_weight() : valence(-1) { }
219 weight_t operator() (void)
220 {
221 #if !defined(OM_CC_MIPS)
222 using std::cos;
223 #endif
224 // 1
225 // alpha(n) = ---- * (40 - ( 3 + 2 cos( 2 Pi / n ) )� )
226 // 64
227
228 if (++valence)
229 {
230 double inv_v = 1.0/double(valence);
231 double t = (3.0 + 2.0 * cos( 2.0 * M_PI * inv_v) );
232 double alpha = (40.0 - t * t)/64.0;
233
234 return weight_t( 1.0-alpha, inv_v*alpha);
235 }
236 return weight_t(0.0, 0.0);
237 }
238 int valence;
239 };
240
241 private: // topological modifiers
242
243 void split_face(mesh_t& _m, const typename mesh_t::FaceHandle& _fh)
244 {
245 typename mesh_t::HalfedgeHandle
246 heh1(_m.halfedge_handle(_fh)),
247 heh2(_m.next_halfedge_handle(_m.next_halfedge_handle(heh1))),
248 heh3(_m.next_halfedge_handle(_m.next_halfedge_handle(heh2)));
249
250 // Cutting off every corner of the 6_gon
251 corner_cutting( _m, heh1 );
252 corner_cutting( _m, heh2 );
253 corner_cutting( _m, heh3 );
254 }
255
256
257 void corner_cutting(mesh_t& _m, const typename mesh_t::HalfedgeHandle& _he)
258 {
259 // Define Halfedge Handles
260 typename mesh_t::HalfedgeHandle
261 heh1(_he),
262 heh5(heh1),
263 heh6(_m.next_halfedge_handle(heh1));
264
265 // Cycle around the polygon to find correct Halfedge
266 for (; _m.next_halfedge_handle(_m.next_halfedge_handle(heh5)) != heh1;
267 heh5 = _m.next_halfedge_handle(heh5))
268 {}
269
270 typename mesh_t::VertexHandle
271 vh1 = _m.to_vertex_handle(heh1),
272 vh2 = _m.to_vertex_handle(heh5);
273
274 typename mesh_t::HalfedgeHandle
275 heh2(_m.next_halfedge_handle(heh5)),
276 heh3(_m.new_edge( vh1, vh2)),
277 heh4(_m.opposite_halfedge_handle(heh3));
278
279 /* Intermediate result
280 *
281 * *
282 * 5 /|\
283 * /_ \
284 * vh2> * *
285 * /|\3 |\
286 * /_ \|4 \
287 * *----\*----\*
288 * 1 ^ 6
289 * vh1 (adjust_outgoing halfedge!)
290 */
291
292 // Old and new Face
293 typename mesh_t::FaceHandle fh_old(_m.face_handle(heh6));
294 typename mesh_t::FaceHandle fh_new(_m.new_face());
295
296
297 // Re-Set Handles around old Face
298 _m.set_next_halfedge_handle(heh4, heh6);
299 _m.set_next_halfedge_handle(heh5, heh4);
300
301 _m.set_face_handle(heh4, fh_old);
302 _m.set_face_handle(heh5, fh_old);
303 _m.set_face_handle(heh6, fh_old);
304 _m.set_halfedge_handle(fh_old, heh4);
305
306 // Re-Set Handles around new Face
307 _m.set_next_halfedge_handle(heh1, heh3);
308 _m.set_next_halfedge_handle(heh3, heh2);
309
310 _m.set_face_handle(heh1, fh_new);
311 _m.set_face_handle(heh2, fh_new);
312 _m.set_face_handle(heh3, fh_new);
313
314 _m.set_halfedge_handle(fh_new, heh1);
315 }
316
317
318 void split_edge(mesh_t& _m, const typename mesh_t::EdgeHandle& _eh)
319 {
320 typename mesh_t::HalfedgeHandle
321 heh = _m.halfedge_handle(_eh, 0),
322 opp_heh = _m.halfedge_handle(_eh, 1);
323
324 typename mesh_t::HalfedgeHandle new_heh, opp_new_heh, t_heh;
325 typename mesh_t::VertexHandle vh;
326 typename mesh_t::VertexHandle vh1(_m.to_vertex_handle(heh));
327 typename mesh_t::Point midP(_m.point(_m.to_vertex_handle(heh)));
328 midP += _m.point(_m.to_vertex_handle(opp_heh));
329 midP *= 0.5;
330
331 // new vertex
332 vh = _m.new_vertex( midP );
333
334 // memorize position, will be set later
335 _m.property( vp_pos_, vh ) = _m.property( ep_pos_, _eh );
336
337
338 // Re-link mesh entities
339 if (_m.is_boundary(_eh))
340 {
341 for (t_heh = heh;
342 _m.next_halfedge_handle(t_heh) != opp_heh;
343 t_heh = _m.opposite_halfedge_handle(_m.next_halfedge_handle(t_heh)))
344 {}
345 }
346 else
347 {
348 for (t_heh = _m.next_halfedge_handle(opp_heh);
349 _m.next_halfedge_handle(t_heh) != opp_heh;
350 t_heh = _m.next_halfedge_handle(t_heh) )
351 {}
352 }
353
354 new_heh = _m.new_edge(vh, vh1);
355 opp_new_heh = _m.opposite_halfedge_handle(new_heh);
356 _m.set_vertex_handle( heh, vh );
357
358 _m.set_next_halfedge_handle(t_heh, opp_new_heh);
359 _m.set_next_halfedge_handle(new_heh, _m.next_halfedge_handle(heh));
360 _m.set_next_halfedge_handle(heh, new_heh);
361 _m.set_next_halfedge_handle(opp_new_heh, opp_heh);
362
363 if (_m.face_handle(opp_heh).is_valid())
364 {
365 _m.set_face_handle(opp_new_heh, _m.face_handle(opp_heh));
366 _m.set_halfedge_handle(_m.face_handle(opp_new_heh), opp_new_heh);
367 }
368
369 _m.set_face_handle( new_heh, _m.face_handle(heh) );
370 _m.set_halfedge_handle( vh, new_heh);
371 _m.set_halfedge_handle( _m.face_handle(heh), heh );
372 _m.set_halfedge_handle( vh1, opp_new_heh );
373
374 // Never forget this, when playing with the topology
375 _m.adjust_outgoing_halfedge( vh );
376 _m.adjust_outgoing_halfedge( vh1 );
377 }
378
379 private: // geometry helper
380
381 void compute_midpoint(mesh_t& _m, const typename mesh_t::EdgeHandle& _eh)
382 {
383 #define V( X ) vector_cast< typename mesh_t::Normal >( X )
384 typename mesh_t::HalfedgeHandle heh, opp_heh;
385
386 heh = _m.halfedge_handle( _eh, 0);
387 opp_heh = _m.halfedge_handle( _eh, 1);
388
389 typename mesh_t::Point
390 pos(_m.point(_m.to_vertex_handle(heh)));
391
392 pos += V( _m.point(_m.to_vertex_handle(opp_heh)) );
393
394 // boundary edge: just average vertex positions
395 if (_m.is_boundary(_eh) )
396 {
397 pos *= 0.5;
398 }
399 else // inner edge: add neighbouring Vertices to sum
400 {
401 pos *= real_t(3.0);
402 pos += V(_m.point(_m.to_vertex_handle(_m.next_halfedge_handle(heh))));
403 pos += V(_m.point(_m.to_vertex_handle(_m.next_halfedge_handle(opp_heh))));
404 pos *= _1over8;
405 }
406 _m.property( ep_pos_, _eh ) = pos;
407 #undef V
408 }
409
410 void smooth(mesh_t& _m, const typename mesh_t::VertexHandle& _vh)
411 {
412 typename mesh_t::Point pos(0.0,0.0,0.0);
413
414 if (_m.is_boundary(_vh) ) // if boundary: Point 1-6-1
415 {
416 typename mesh_t::HalfedgeHandle heh, prev_heh;
417 heh = _m.halfedge_handle( _vh );
418
419 if ( heh.is_valid() )
420 {
421 assert( _m.is_boundary( _m.edge_handle( heh ) ) );
422
423 prev_heh = _m.prev_halfedge_handle( heh );
424
425 typename mesh_t::VertexHandle
426 to_vh = _m.to_vertex_handle( heh ),
427 from_vh = _m.from_vertex_handle( prev_heh );
428
429 // ( v_l + 6 v + v_r ) / 8
430 pos = _m.point( _vh );
431 pos *= real_t(6.0);
432 pos += vector_cast< typename mesh_t::Normal >( _m.point( to_vh ) );
433 pos += vector_cast< typename mesh_t::Normal >( _m.point( from_vh ) );
434 pos *= _1over8;
435
436 }
437 else
438 return;
439 }
440 else // inner vertex: (1-a) * p + a/n * Sum q, q in one-ring of p
441 {
442 typedef typename mesh_t::Normal Vec;
443 typename mesh_t::VertexVertexIter vvit;
444 size_t valence(0);
445
446 // Calculate Valence and sum up neighbour points
447 for (vvit=_m.vv_iter(_vh); vvit.is_valid(); ++vvit) {
448 ++valence;
449 pos += vector_cast< Vec >( _m.point(*vvit) );
450 }
451 pos *= weights_[valence].second; // alpha(n)/n * Sum q, q in one-ring of p
452 pos += weights_[valence].first
453 * vector_cast<Vec>(_m.point(_vh)); // + (1-a)*p
454 }
455
456 _m.property( vp_pos_, _vh ) = pos;
457 }
458
459 private: // data
460
461 OpenMesh::VPropHandleT< typename mesh_t::Point > vp_pos_;
462 OpenMesh::EPropHandleT< typename mesh_t::Point > ep_pos_;
463
464 weights_t weights_;
465
466 const real_t _1over8;
467 const real_t _3over8;
468
469 };
470
471
472 //=============================================================================
473 } // END_NS_UNIFORM
474 } // END_NS_SUBDIVIDER
475 } // END_NS_OPENMESH
476 //=============================================================================
477 #endif // OPENMESH_SUBDIVIDER_UNIFORM_COMPOSITELOOPT_HH defined
478 //=============================================================================
OpenMesh::PolyMeshT::Point
Kernel::Point Point
Coordinate type.
Definition: PolyMeshT.hh:115
OpenMesh::PolyMeshT::Normal
Kernel::Normal Normal
Normal type.
Definition: PolyMeshT.hh:117
OpenMesh::Utils::MeshCheckerT
Check integrity of mesh.
Definition: MeshCheckerT.hh:78
OpenMesh::EPropHandleT< typename mesh_t::Point >
SubdividerT.hh
OpenMesh::VPropHandleT< typename mesh_t::Point >
OpenMesh::PolyMeshT::VertexVertexIter
Kernel::VertexVertexIter VertexVertexIter
Circulator.
Definition: PolyMeshT.hh:165
OpenMesh::Subdivider::Uniform::LoopT::prepare
bool prepare(mesh_t &_m)
Prepare mesh, e.g. add properties.
Definition: LoopT.hh:138
OpenMesh::Subdivider::Uniform::LoopT::name
const char * name() const
Return name of subdivision algorithm.
Definition: LoopT.hh:124
OpenMesh::Subdivider::Uniform::SubdividerT::operator()
bool operator()(MeshType &_m, size_t _n, const bool _update_points=true)
Subdivide the mesh _m _n times.
Definition: SubdividerT.hh:128
OpenMesh::PolyMeshT::VertexHandle
Kernel::VertexHandle VertexHandle
Handle for referencing the corresponding item.
Definition: PolyMeshT.hh:139
OpenMesh::Subdivider::Uniform::LoopT::subdivide
bool subdivide(mesh_t &_m, size_t _n, const bool _update_points=true)
Subdivide mesh _m _n times.
Definition: LoopT.hh:154
OpenMesh::PolyMeshT::new_vertex
VertexHandle new_vertex()
Uses default copy and assignment operator.
Definition: PolyMeshT.hh:202
OpenMesh::vector_cast
void vector_cast(const src_t &_src, dst_t &_dst, GenProg::Int2Type< n >)
Cast vector type to another vector type by copying the vector elements.
Definition: vector_cast.hh:86
OpenMesh
Contains all the mesh ingredients like the polygonal mesh, the triangle mesh, different mesh kernels ...
Definition: MeshItems.hh:64
OpenMesh::Subdivider::Uniform::LoopT::cleanup
bool cleanup(mesh_t &_m)
Cleanup mesh after usage, e.g. remove added properties.
Definition: LoopT.hh:146
OpenMesh::Subdivider::Uniform::LoopT
Uniform Loop subdivision algorithm.
Definition: LoopT.hh:96
OpenMesh::Subdivider::Uniform::LoopT::init_weights
void init_weights(size_t _max_valence=50)
Pre-compute weights.
Definition: LoopT.hh:128
OpenMesh::Subdivider::Uniform::SubdividerT
Abstract base class for uniform subdivision algorithms.
Definition: SubdividerT.hh:94