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Now zonohedra construction robust to basically *any* input, no matter how degenerate.

This commit is contained in:
mtarini 2012-07-24 01:48:21 +00:00
parent 0448e15f5b
commit 3adc453f53
1 changed files with 25 additions and 8 deletions
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33
vcg/complex/algorithms/create/zonohedron.h
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@ -132,8 +132,17 @@ private:
return -v;
}
static Vec3 altVec(int i) {
return Vec3(1, i, i*i);
}
static Scalar tripleProduct( const Vec3 &a, const Vec3 &b, const Vec3 & c){
return ( a ^ b ) * c;
}
// returns signof: (i x j) * k
bool signOf_IxJoK(VecIndex i, VecIndex j, VecIndex k){
const float EPSILON_SQUARED = 1e-12;
bool invert = false;
// sort i,j,k
if (i<j) { std::swap(i,j); invert = !invert; }
@ -144,15 +153,23 @@ private:
//Scalar res = Vec3::dot( Vec3::cross( vec[i] , vec[j] ) , vec[k] );
Scalar res = cross( i , j ) * vec[k] ;
if (res==0) {
if (res*res<=EPSILON_SQUARED) {
// three coplanar vectors!
res = uniqueVerse( cross(i,j) ) * cross(j,k) ;
/*if (res==0) {
printf("COLINEAR\n");
// three colinear vectors!
res = Vec3::dot( uniqueVerse(vec[i]) , vec[j])*
Vec3::dot( uniqueVerse(vec[i]) , vec[k]);
}*/
// use derivative...
//res = uniqueVerse( cross(i,j) ) * cross(j,k) ;
res = tripleProduct( altVec(i), vec[j], vec[k]) +
tripleProduct( vec[i], altVec(j), vec[k]) +
tripleProduct( vec[i], vec[j], altVec(k)) ;
if (res*res<=EPSILON_SQUARED) {
// zero derivative (happens, if three colinear vectors, or...)
res = tripleProduct( vec[i], altVec(j), altVec(k)) +
tripleProduct( altVec(i), vec[j], altVec(k)) +
tripleProduct( altVec(i), altVec(j), vec[k]) ;
}
if (res*res<=EPSILON_SQUARED) {
// zero second derivative (happens if three zero-vectors, i.e. never? or...)
res = tripleProduct( altVec(i), altVec(j), altVec(k) );
}
}
return ( (res>=0) != invert ); // XOR