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New function for computing baric coords in a more robust way

This commit is contained in:
Paolo Cignoni 2009-01-08 11:24:54 +00:00
parent 20272bf7ac
commit 3e85ffd0ff
1 changed files with 55 additions and 0 deletions
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55
vcg/space/triangle3.h
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@ -94,6 +94,7 @@ Initial commit
#define __VCG_TRIANGLE3
#include <vcg/space/box3.h>
#include <vcg/space/point2.h>
#include <vcg/space/point3.h>
#include <vcg/space/plane3.h>
#include <vcg/space/segment3.h>
@ -163,6 +164,60 @@ typename TriangleType::ScalarType QualityFace(const TriangleType &t)
return Quality(t.cP(0), t.cP(1), t.cP(2));
}
// More robust function to computing barycentric coords of a point inside a triangle.
// it requires the knowledge of what is the direction that is more orthogonal to the face plane.
// Usually this info can be stored in a bit of the face flags (see updateFlags class members)
// This direction is used to project the triangle in 2D and solve the problem in 2D where it is well defined.
template<class TriangleType, class ScalarType>
bool InterpolationParameters(const TriangleType t, const int Axis, const Point3<ScalarType> & P, Point3<ScalarType> & L)
{
Point2<ScalarType> test;
typedef Point2<ScalarType> P2;
if(Axis==0) return InterpolationParameters2( P2(t.P(0)[1],t.P(0)[2]), P2(t.P(1)[1],t.P(1)[2]), P2(t.P(2)[1],t.P(2)[2]), P2(P[1],P[2]), L);
if(Axis==1) return InterpolationParameters2( P2(t.P(0)[0],t.P(0)[2]), P2(t.P(1)[0],t.P(1)[2]), P2(t.P(2)[0],t.P(2)[2]), P2(P[0],P[2]), L);
if(Axis==2) return InterpolationParameters2( P2(t.P(0)[0],t.P(0)[1]), P2(t.P(1)[0],t.P(1)[1]), P2(t.P(2)[0],t.P(2)[1]), P2(P[0],P[1]), L);
return false;
}
// Function that computes the barycentric coords of a 2D triangle. Used by the above function.
// Algorithm: simply find a base for the frame of the triangle, assuming v3 as origin (matrix T) invert it and apply to P-v3.
template<class ScalarType>
bool InterpolationParameters2(const Point2<ScalarType> &V1,
const Point2<ScalarType> &V2,
const Point2<ScalarType> &V3,
const Point2<ScalarType> &P, Point3<ScalarType> &L)
{
ScalarType T00 = V1[0]-V3[0]; ScalarType T01 = V2[0]-V3[0];
ScalarType T10 = V1[1]-V3[1]; ScalarType T11 = V2[1]-V3[1];
ScalarType Det = T00 * T11 - T01*T10;
if(fabs(Det) < 0.0000001)
return false;
ScalarType IT00 = T11/Det; ScalarType IT01 = -T01/Det;
ScalarType IT10 = -T10/Det; ScalarType IT11 = T00/Det;
Point2<ScalarType> Delta = P-V3;
L[0] = IT00*Delta[0] + IT01*Delta[1];
L[1] = IT10*Delta[0] + IT11*Delta[1];
if(L[0]<0) L[0]=0;
if(L[1]<0) L[1]=0;
if(L[0]>1.) L[0]=1;
if(L[1]>1.) L[1]=1;
L[2] = 1. - L[1] - L[0];
if(L[2]<0) L[2]=0;
assert(L[2] >= -0.00001);
return true;
}
/** Calcola i coefficienti della combinazione convessa.
@param bq Punto appartenente alla faccia
@param a Valore di ritorno per il vertice V(0)