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added 1-4 triangle midpoint subdivision
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@mlivesu
mlivesu committed Mar 12, 2024
1 parent caf8e6c commit 9c50a57
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92 changes: 92 additions & 0 deletions include/cinolib/subdivision_1_to_4.cpp
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/********************************************************************************
* This file is part of CinoLib *
* Copyright(C) 2024: Marco Livesu *
* *
* The MIT License *
* *
* Permission is hereby granted, free of charge, to any person obtaining a *
* copy of this software and associated documentation files (the "Software"), *
* to deal in the Software without restriction, including without limitation *
* the rights to use, copy, modify, merge, publish, distribute, sublicense, *
* and/or sell copies of the Software, and to permit persons to whom the *
* Software is furnished to do so, subject to the following conditions: *
* *
* The above copyright notice and this permission notice shall be included in *
* all copies or substantial portions of the Software. *
* *
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR *
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, *
* FITNESS FOR A PARTICULAR PURPOSE AND NON INFRINGEMENT. IN NO EVENT SHALL THE *
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER *
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING *
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS *
* IN THE SOFTWARE. *
* *
* Author(s): *
* *
* Marco Livesu ([email protected]) *
* http://pers.ge.imati.cnr.it/livesu/ *
* *
* Italian National Research Council (CNR) *
* Institute for Applied Mathematics and Information Technologies (IMATI) *
* Via de Marini, 6 *
* 16149 Genoa, *
* Italy *
*********************************************************************************/
#include <cinolib/subdivision_1_to_4.h>

namespace cinolib
{

// Splits each mesh triangle into 4 subtriangles, splitting mesh edges at their midpoint
//
template<class M, class V, class E, class P>
CINO_INLINE
void subdivision_1_to_4(Trimesh<M,V,E,P> & m)
{
uint nv = m.num_verts();

// add edge midpoints
for(uint eid=0; eid<m.num_edges(); ++eid)
{
m.vert_add(m.edge_sample_at(eid,0.5));
}

// create subtriangles
uint np = m.num_polys();
for(uint pid=0; pid<np; ++pid)
{
auto v = m.poly_verts_id(pid);
if(!m.poly_verts_are_CCW(pid,v[1],v[0])) std::swap(v[1],v[0]);

// v2
// / \
// e02 -- e12
// / \ / \
// v0 -- e01 -- v1

int e01 = m.edge_id(v[0],v[1]); assert(e01>=0);
int e12 = m.edge_id(v[1],v[2]); assert(e12>=0);
int e02 = m.edge_id(v[0],v[2]); assert(e02>=0);

uint v01 = nv + e01;
uint v12 = nv + e12;
uint v02 = nv + e02;

m.poly_add(v[0], v01, v02);
m.poly_add( v01, v12, v02);
m.poly_add( v01,v[1], v12);
m.poly_add( v02, v12,v[2]);
}

// remove old triangles
//
// NOTE: since I am deleting all original triangles, it would probably be
// more efficient to just rebuild the mesh from scratch. However, I may have
// custom data attached to the mesh elements that I want to save....
std::vector<uint> del(np);
std::iota(del.begin(),del.end(),0);
m.polys_remove(del);
}

}
56 changes: 56 additions & 0 deletions include/cinolib/subdivision_1_to_4.h
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/********************************************************************************
* This file is part of CinoLib *
* Copyright(C) 2024: Marco Livesu *
* *
* The MIT License *
* *
* Permission is hereby granted, free of charge, to any person obtaining a *
* copy of this software and associated documentation files (the "Software"), *
* to deal in the Software without restriction, including without limitation *
* the rights to use, copy, modify, merge, publish, distribute, sublicense, *
* and/or sell copies of the Software, and to permit persons to whom the *
* Software is furnished to do so, subject to the following conditions: *
* *
* The above copyright notice and this permission notice shall be included in *
* all copies or substantial portions of the Software. *
* *
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR *
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, *
* FITNESS FOR A PARTICULAR PURPOSE AND NON INFRINGEMENT. IN NO EVENT SHALL THE *
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER *
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING *
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS *
* IN THE SOFTWARE. *
* *
* Author(s): *
* *
* Marco Livesu ([email protected]) *
* http://pers.ge.imati.cnr.it/livesu/ *
* *
* Italian National Research Council (CNR) *
* Institute for Applied Mathematics and Information Technologies (IMATI) *
* Via de Marini, 6 *
* 16149 Genoa, *
* Italy *
*********************************************************************************/
#ifndef CINO_SUBDIVISION_1_TO_4_H
#define CINO_SUBDIVISION_1_TO_4_H

#include <cinolib/meshes/trimesh.h>

namespace cinolib
{

// Splits each mesh triangle into 4 subtriangles, splitting mesh edges at their midpoint
//
template<class M, class V, class E, class P>
CINO_INLINE
void subdivision_1_to_4(Trimesh<M,V,E,P> & m);

}

#ifndef CINO_STATIC_LIB
#include "subdivision_1_to_4.cpp"
#endif

#endif // CINO_SUBDIVISION_1_TO_4_H

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