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improved loss of precision minimization

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This commit is contained in:
Paolo Cignoni cignoni 2008-04-26 13:45:48 +00:00
parent bd7334aa8d
commit 3021ef4b02
1 changed files with 39 additions and 3 deletions
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42
src/meshlabplugins/meshfilter/quadric5.h
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@ -23,6 +23,9 @@
/****************************************************************************
History
$Log$
Revision 1.7 2008/04/26 13:45:48 pirosu
improved loss of precision minimization
Revision 1.6 2008/04/26 12:50:32 pirosu
commented assert
@ -188,6 +191,8 @@ public:
// Computes the geometrical quadric if onlygeo == true and the real quadric if onlygeo == false
void byFace(FaceType &fi, bool onlygeo)
{
double minerror = std::numeric_limits<double>::max();
int minerror_index = 0;
ScalarType pe1;
ScalarType pe2;
ScalarType tmpmat[5][5];
@ -259,9 +264,9 @@ public:
/*
When c is very close to 0, loss of precision causes it to be computed as a negative number,
which is invalid for a quadric. Vertex switches are performed in order to try to obtain a smaller
loss of precision
loss of precision. The one with the smallest error is chosen.
*/
for(int i = 0; i < 6; i++) // tries the 6! configurations
for(int i = 0; i < 7; i++) // tries the 6! configurations and chooses the one with the smallest error
{
switch(i)
{
@ -276,6 +281,29 @@ public:
case 4:
swapv(p,r);
break;
case 6: // every swap has loss of precision
swapv(p,r);
for(int j = 0; j <= minerror_index; j++)
{
switch(j)
{
case 0:
break;
case 1:
case 3:
case 5:
swapv(q,r);
break;
case 2:
case 4:
swapv(p,r);
break;
default:
assert(0);
}
}
minerror_index = -1;
break;
default:
assert(0);
}
@ -331,7 +359,15 @@ public:
// computes c
c = math::inproduct5(p,p)-pe1*pe1-pe2*pe2;
if(IsValid())return;
if(IsValid())
return;
else if (minerror_index == -1) // the one with the smallest error has been computed
break;
else if(-c < minerror)
{
minerror = -c;
minerror_index = i;
}
}
// failed to find a valid vertex switch