/*===========================================================================*\
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/*===========================================================================*\
 *                                                                           *
 *   $Revision: 448 $                                                        *
 *   $Date: 2011-11-04 13:59:37 +0100 (Fri, 04 Nov 2011) $                   *
 *                                                                           *
 \*===========================================================================*/

/** \file ModAspectRatioT.cc
 */

//=============================================================================
//
//  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) {
  Point d0 = _v0 - _v1;
  Point d1 = _v1 - _v2;

  // finds the max squared edge length
  Scalar l2, maxl2 = d0.sqrnorm();
  if ((l2 = d1.sqrnorm()) > maxl2)
    maxl2 = l2;
  // keep searching for the max squared edge length
  d1 = _v2 - _v0;
  if ((l2 = d1.sqrnorm()) > maxl2)
    maxl2 = l2;

  // squared area of the parallelogram spanned by d0 and d1
  Scalar a2 = (d0 % d1).sqrnorm();

  // 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
  return sqrt((maxl2 * maxl2) / a2);
}

//-----------------------------------------------------------------------------

template<class MeshT>
void ModAspectRatioT<MeshT>::initialize() {
  typename Mesh::FaceIter f_it, f_end(mesh_.faces_end());
  typename Mesh::FVIter fv_it;

  for (f_it = mesh_.faces_begin(); f_it != f_end; ++f_it) {
    typename Mesh::Point& p0 = mesh_.point(fv_it = mesh_.fv_iter(f_it));
    typename Mesh::Point& p1 = mesh_.point(++fv_it);
    typename Mesh::Point& p2 = mesh_.point(++fv_it);

    mesh_.property(aspect_, f_it) = 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; ++vf_it) {
    fh = vf_it.handle();
    if (fh != _ci.fl && fh != _ci.fr) {
      typename Mesh::Point& p0 = mesh_.point(fv_it = mesh_.fv_iter(fh));
      typename Mesh::Point& p1 = mesh_.point(++fv_it);
      typename Mesh::Point& p2 = mesh_.point(++fv_it);

      mesh_.property(aspect_, fh) = 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), *p2, *p3;
  typename Mesh::Scalar r0, r1, r0_min(1.0), r1_min(1.0);
  typename Mesh::CVVIter vv_it(mesh_, _ci.v0);

  v3 = vv_it.handle();
  p3 = &mesh_.point(v3);

  while (vv_it) {
    v2 = v3;
    p2 = p3;

    v3 = (++vv_it).handle();
    p3 = &mesh_.point(v3);

    fh = mesh_.face_handle(vv_it.current_halfedge_handle());

    // 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 = 1.0 / aspectRatio(*p1, *p2, *p3)) < r1_min)
          r1_min = r1;
    }
  }

  if (Base::is_binary()) {
    return
        ((r1_min > r0_min) || (r1_min > min_aspect_)) ? Base::LEGAL_COLLAPSE :
            Base::ILLEGAL_COLLAPSE;

  } else {
    if (r1_min > r0_min)
      return 1.0 - r1_min;
    else
      return
          (r1_min > min_aspect_) ? 2.0 - r1_min : float(Base::ILLEGAL_COLLAPSE);
  }
}

//=============================================================================
}
}
//=============================================================================