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Added two different methods for computing vertex normals from facet normals, weighted and weighted by angle

This commit is contained in:
Paolo Cignoni 2009-04-10 14:21:00 +00:00
parent 8be6f002a3
commit 47dc2ecd6c
1 changed files with 69 additions and 2 deletions
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71
vcg/complex/trimesh/update/normal.h
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@ -179,14 +179,81 @@ static void PerFaceFromCurrentVertexNormal(ComputeMeshType &m)
fi->N() = n;
}
}
/// \brief Calculates the vertex normal. Without exploiting or touching face normals.
/**
The normal of a vertex v is the weigthed average of the normals of the faces incident on v.
The normal of a vertex v computed as a weighted sum f the incident face normals.
The weight is simlply the angle of the involved wedge. Described in:
G. Thurmer, C. A. Wuthrich
"Computing vertex normals from polygonal facets"
Journal of Graphics Tools, 1998
*/
static void PerVertexAngleWeighted(ComputeMeshType &m)
{
assert(HasPerVertexNormal(m));
VertexIterator vi;
for(vi=m.vert.begin();vi!=m.vert.end();++vi)
if( !(*vi).IsD() && (*vi).IsRW() )
(*vi).N() = NormalType((ScalarType)0,(ScalarType)0,(ScalarType)0);
FaceIterator f;
for(f=m.face.begin();f!=m.face.end();++f)
if( !(*f).IsD() && (*f).IsR() )
{
typename FaceType::NormalType t = vcg::NormalizedNormal(*f);
NormalType e0 = ((*f).V1(0)->cP()-(*f).V0(0)->cP()).Normalize();
NormalType e1 = ((*f).V1(1)->cP()-(*f).V0(1)->cP()).Normalize();
NormalType e2 = ((*f).V1(2)->cP()-(*f).V0(2)->cP()).Normalize();
(*f).V(0)->N() += t*AngleN(e0,-e2);
(*f).V(1)->N() += t*AngleN(-e0,e1);
(*f).V(2)->N() += t*AngleN(-e1,e2);
}
}
/// \brief Calculates the vertex normal. Without exploiting or touching face normals.
/**
The normal of a vertex v is computed according to the formula described by Nelson Max in
Max, N., "Weights for Computing Vertex Normals from Facet Normals", Journal of Graphics Tools, 4(2) (1999)
The weight for each wedge is the cross product of the two edge over the product of the square of the two edge lengths.
According to the original paper it is perfect only for spherical surface, but it should perform well...
*/
static void PerVertexWeighted(ComputeMeshType &m)
{
assert(HasPerVertexNormal(m));
VertexIterator vi;
for(vi=m.vert.begin();vi!=m.vert.end();++vi)
if( !(*vi).IsD() && (*vi).IsRW() )
(*vi).N() = NormalType((ScalarType)0,(ScalarType)0,(ScalarType)0);
FaceIterator f;
for(f=m.face.begin();f!=m.face.end();++f)
if( !(*f).IsD() && (*f).IsR() )
{
typename FaceType::NormalType t = vcg::Normal(*f);
ScalarType e0 = SquaredDistance((*f).V0(0)->cP(),(*f).V1(0)->cP());
ScalarType e1 = SquaredDistance((*f).V0(1)->cP(),(*f).V1(1)->cP());
ScalarType e2 = SquaredDistance((*f).V0(2)->cP(),(*f).V1(2)->cP());
(*f).V(0)->N() += t/(e0*e2);
(*f).V(1)->N() += t/(e0*e1);
(*f).V(2)->N() += t/(e1*e2);
}
}
/// \brief Calculates the vertex normal. Without exploiting or touching face normals.
/**
The normal of a vertex v is the classical area weigthed average of the normals of the faces incident on v.
*/
static void PerVertex(ComputeMeshType &m)
{
if( !m.HasPerVertexNormal()) return;
assert(HasPerVertexNormal(m));
VertexIterator vi;
for(vi=m.vert.begin();vi!=m.vert.end();++vi)