NormalAttribT_impl.hh

/*===========================================================================*\
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 *                            OpenVolumeMesh                                 *
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#define NORMALATTRIBT_CC

#include <set>

#include "NormalAttrib.hh"

#include "../Core/GeometryKernel.hh"

namespace OpenVolumeMesh {

template <class GeomKernelT>
NormalAttrib<GeomKernelT>::NormalAttrib(GeomKernelT& _kernel) :
kernel_(_kernel),
v_normals_(_kernel.template request_vertex_property<typename GeomKernelT::PointT>("vertex_normals", typename GeomKernelT::PointT(0.0))),
f_normals_(_kernel.template request_face_property<typename GeomKernelT::PointT>("face_normals", typename GeomKernelT::PointT(0.0)))
{

}

template <class GeomKernelT>
NormalAttrib<GeomKernelT>::~NormalAttrib() {

}

template <class GeomKernelT>
void NormalAttrib<GeomKernelT>::update_vertex_normals() {

    if(!kernel_.has_face_bottom_up_incidences()) {
        std::cerr << "Error: update_vertex_normals() needs bottom-up incidences!" << std::endl;
        return;
    }

    // Compute face normals
    update_face_normals();

    for(VertexIter v_it = kernel_.v_iter(); v_it.valid(); ++v_it) {
        compute_vertex_normal(*v_it);
    }
}

template <class GeomKernelT>
void NormalAttrib<GeomKernelT>::update_face_normals() {

    if(!kernel_.has_face_bottom_up_incidences()) {
        std::cerr << "Error: update_normals() needs bottom-up incidences!" << std::endl;
        return;
    }

    for(FaceIter f_it = kernel_.f_iter(); f_it.valid(); ++f_it) {
        // Assume the face is planar, so just take the
        // first two edges
        compute_face_normal(*f_it);
    }
}

template <class GeomKernelT>
void NormalAttrib<GeomKernelT>::compute_vertex_normal(const VertexHandle& _vh) {

    std::set<HalfFaceHandle> halffaces;
    for(VertexOHalfEdgeIter voh_it = kernel_.voh_iter(_vh);
            voh_it.valid(); ++voh_it) {

        for(HalfEdgeHalfFaceIter hehf_it = kernel_.hehf_iter(*voh_it);
                hehf_it.valid(); ++hehf_it) {
            if(kernel_.is_boundary(*hehf_it)) {
                halffaces.insert(*hehf_it);
            }
        }
    }
    typename GeomKernelT::PointT normal = typename GeomKernelT::PointT(0.0);
    for(std::set<HalfFaceHandle>::const_iterator hf_it = halffaces.begin();
            hf_it != halffaces.end(); ++hf_it) {
        normal += (*this)[*hf_it];
    }

    normal.normalize();

    v_normals_[_vh] = normal;
}

template <class GeomKernelT>
void NormalAttrib<GeomKernelT>::compute_face_normal(const FaceHandle& _fh) {

    if(kernel_.face(_fh).halfedges().size() < 3) {
        std::cerr << "Warning: Degenerate face detected!" << std::endl;
        return;
    }

    const std::vector<HalfEdgeHandle>& halfedges = kernel_.face(_fh).halfedges();
    std::vector<HalfEdgeHandle>::const_iterator he_it = halfedges.begin();

    typename GeomKernelT::PointT p1 = kernel_.vertex(kernel_.halfedge(*he_it).from_vertex());
    typename GeomKernelT::PointT p2 = kernel_.vertex(kernel_.halfedge(*he_it).to_vertex());
    ++he_it;
    typename GeomKernelT::PointT p3 = kernel_.vertex(kernel_.halfedge(*he_it).to_vertex());

    typename GeomKernelT::PointT n = (p2 - p1) % (p3 - p2);
    n.normalize();

    f_normals_[_fh] = n;
}

} // Namespace OpenVolumeMesh