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Calculate average normal for poly mesh faces. Otherwise an arbitrary triangle is taken

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git-svn-id: http://www.openmesh.org/svnrepo/OpenMesh/trunk@309 fdac6126-5c0c-442c-9429-916003d36597
This commit is contained in:
Jan Möbius
2010-03-09 13:32:23 +00:00
parent c0ea2968e3
commit 13204f4afc
4 changed files with 53 additions and 9 deletions
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34
src/OpenMesh/Core/Mesh/PolyMeshT.cc
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@@ -95,15 +95,37 @@ calc_face_normal(FaceHandle _fh) const
{
assert(halfedge_handle(_fh).is_valid());
ConstFaceVertexIter fv_it(cfv_iter(_fh));
Point p0 = point(fv_it);
Point p0i = p0; //save point of vertex 0
++fv_it;
Point p1 = point(fv_it);
Point p1i = p1; //save point of vertex 1
++fv_it;
Point p2;
//calculate area-weighted average normal of polygon's ears
Normal n(0,0,0);
for(; fv_it; ++fv_it)
{
p2 = point(fv_it);
n += vector_cast<Normal>((p2-p1)%(p0-p1));
p0 = p1;
p1 = p2;
}
//two additional steps since we started at vertex 2, not 0
n += vector_cast<Normal>((p0i-p1)%(p0-p1));
n += vector_cast<Normal>((p1i-p0i)%(p1-p0i));
const Point& p0(point(fv_it)); ++fv_it;
const Point& p1(point(fv_it)); ++fv_it;
const Point& p2(point(fv_it));
return calc_face_normal(p0, p1, p2);
typename Normal::value_type norm = n.length();
// The expression ((n *= (1.0/norm)),n) is used because the OpenSG
// vector class does not return self after component-wise
// self-multiplication with a scalar!!!
return (norm != typename Normal::value_type(0)) ? ((n *= (typename Normal::value_type(1)/norm)),n) : Normal(0,0,0);
}
//-----------------------------------------------------------------------------