ModAspectRatioT_impl.hh

Go to the documentation of this file.

/* ========================================================================= *
 *                                                                           *
 *                               OpenMesh                                    *
 *           Copyright (c) 2001-2025, RWTH-Aachen University                 *
 *           Department of Computer Graphics and Multimedia                  *
 *                          All rights reserved.                             *
 *                            www.openmesh.org                               *
 *                                                                           *
 *---------------------------------------------------------------------------*
 * This file is part of OpenMesh.                                            *
 *---------------------------------------------------------------------------*
 *                                                                           *
 * Redistribution and use in source and binary forms, with or without        *
 * modification, are permitted provided that the following conditions        *
 * are met:                                                                  *
 *                                                                           *
 * 1. Redistributions of source code must retain the above copyright notice, *
 *    this list of conditions and the following disclaimer.                  *
 *                                                                           *
 * 2. Redistributions in binary form must reproduce the above copyright      *
 *    notice, this list of conditions and the following disclaimer in the    *
 *    documentation and/or other materials provided with the distribution.   *
 *                                                                           *
 * 3. Neither the name of the copyright holder nor the names of its          *
 *    contributors may be used to endorse or promote products derived from   *
 *    this software without specific prior written permission.               *
 *                                                                           *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS       *
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED *
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A           *
 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER *
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,  *
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,       *
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR        *
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF    *
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING      *
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS        *
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.              *
 *                                                                           *
 * ========================================================================= */
 
 
//=============================================================================
//
//  CLASS ModAspectRatioT - IMPLEMENTATION
//
//=============================================================================
#define OPENMESH_DECIMATER_MODASPECTRATIOT_C
 
//== INCLUDES =================================================================
 
#include "ModAspectRatioT.hh"
 
//== NAMESPACES ===============================================================
 
namespace OpenMesh {
namespace Decimater {
 
//== IMPLEMENTATION ==========================================================
 
template<class MeshT>
typename ModAspectRatioT<MeshT>::Scalar ModAspectRatioT<MeshT>::aspectRatio(
    const Point& _v0, const Point& _v1, const Point& _v2) {
 
  // Egde vectors
  const Point d0 = _v0 - _v1;
  const Point d1 = _v1 - _v2;
  const Point d2 = _v2 - _v0;
 
  // squared edge lengths
  const Scalar l0 = sqrnorm(d0);
  const Scalar l1 = sqrnorm(d1);
  const Scalar l2 = sqrnorm(d2);
 
  // find the maximal squared edge length
  const Scalar maxl2 = std::max(l0, std::max(l1, l2));
 
  // squared area of the parallelogram spanned by d0 and d2
  // (twice the triangle's area, magnitude independent of which two edges are chosen)
  Scalar a2 = sqrnorm(d0 % d2);
 
  // the area of the triangle would be
  // sqrt(a2)/2 or length * height / 2
  // aspect ratio = length / height
  //              = length * length / (2*area)
  //              = length * length / sqrt(a2)
 
  // returns the length of the longest edge
  //         divided by its corresponding height
  // As maxl2 is positive, we can reduce that from sqrt((maxl2 * maxl2) / a2) to the following:
  return maxl2 / sqrt(a2);
}
 
//-----------------------------------------------------------------------------
 
template<class MeshT>
void ModAspectRatioT<MeshT>::initialize() {
 
 for (const auto& fh : mesh_.faces())
  {
    auto fv_it = mesh_.cfv_iter(fh);
 
    const typename Mesh::Point& p0 = mesh_.point(*fv_it);
    const typename Mesh::Point& p1 = mesh_.point(*(++fv_it));
    const typename Mesh::Point& p2 = mesh_.point(*(++fv_it));
 
    mesh_.property(aspect_, fh) = static_cast<typename Mesh::Scalar>(1.0) / aspectRatio(p0, p1, p2);
  }
 
}
 
//-----------------------------------------------------------------------------
 
template<class MeshT>
void ModAspectRatioT<MeshT>::preprocess_collapse(const CollapseInfo& _ci) {
  typename Mesh::FaceHandle fh;
  typename Mesh::FVIter fv_it;
 
  for (typename Mesh::VFIter vf_it = mesh_.vf_iter(_ci.v0); vf_it.is_valid(); ++vf_it) {
    fh = *vf_it;
    if (fh != _ci.fl && fh != _ci.fr) {
      fv_it = mesh_.fv_iter(fh);
      typename Mesh::Point& p0 = mesh_.point(*fv_it);
      typename Mesh::Point& p1 = mesh_.point(*(++fv_it));
      typename Mesh::Point& p2 = mesh_.point(*(++fv_it));
 
      mesh_.property(aspect_, fh) = static_cast<typename Mesh::Scalar>(1.0) / aspectRatio(p0, p1, p2);
    }
  }
}
 
//-----------------------------------------------------------------------------
 
template<class MeshT>
float ModAspectRatioT<MeshT>::collapse_priority(const CollapseInfo& _ci) {
  typename Mesh::VertexHandle v2, v3;
  typename Mesh::FaceHandle fh;
  const typename Mesh::Point* p1(&_ci.p1);
  typename Mesh::Scalar r0, r1, r0_min(1.0), r1_min(1.0);
  typename Mesh::ConstVertexOHalfedgeIter voh_it(mesh_, _ci.v0);
 
  v3 = mesh_.to_vertex_handle(*voh_it);
  auto p3 = &mesh_.point(v3);
 
  while (voh_it.is_valid()) {
    v2 = v3;
    auto p2 = p3;
 
    ++voh_it;
    v3 = mesh_.to_vertex_handle(*voh_it);
    p3 = &mesh_.point(v3);
 
    fh = mesh_.face_handle(*voh_it);
 
    // if not boundary
    if (fh.is_valid()) {
      // aspect before
      if ((r0 = mesh_.property(aspect_, fh)) < r0_min)
        r0_min = r0;
 
      // aspect after
      if (!(v2 == _ci.v1 || v3 == _ci.v1))
        if ((r1 = static_cast<typename Mesh::Scalar>(1.0) / aspectRatio(*p1, *p2, *p3)) < r1_min)
          r1_min = r1;
    }
  }
 
  if (Base::is_binary()) {
    return
        ((r1_min > r0_min) || (r1_min > min_aspect_)) ? float(Base::LEGAL_COLLAPSE) :
            float(Base::ILLEGAL_COLLAPSE);
 
  } else {
    if (r1_min > r0_min)
      return 1.f - float(r1_min);
    else
      return
          (r1_min > min_aspect_) ? 2.f - float(r1_min) : float(Base::ILLEGAL_COLLAPSE);
  }
}
 
//-----------------------------------------------------------------------------
 
template<class MeshT>
void ModAspectRatioT<MeshT>::set_error_tolerance_factor(double _factor) {
  if (_factor >= 0.0 && _factor <= 1.0) {
    // the smaller the factor, the larger min_aspect_ gets
    // thus creating a stricter constraint
    // division by (2.0 - error_tolerance_factor_) is for normalization
    float min_aspect = min_aspect_ * (2.f - float(_factor)) / (2.f - float(this->error_tolerance_factor_));
    set_aspect_ratio(1.f/min_aspect);
    this->error_tolerance_factor_ = _factor;
  }
}
 
//=============================================================================
}
}
//=============================================================================