manolas
/
vcglib
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

corrected InterpolationParameters funtion in order to evaluate correctly barycentric coordinates even for points wich falls outside the triangle.

This commit is contained in:
Nico Pietroni 2010-12-12 23:59:55 +00:00
parent 387c62414a
commit 542bfc8a91
1 changed files with 25 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

58
vcg/space/triangle2.h
View File

@ -77,47 +77,39 @@ public:
/** evaluate barycentric coordinates
@param bq Point on the face
@param a barycentric value for V(0)
@param b barycentric value for V(1)
@param c barycentric value for V(2)
@param L0 barycentric value for V(0)
@param L1 barycentric value for V(1)
@param L2 barycentric value for V(2)
@return true se bq appartain to the face, false otherwise
from http://en.wikipedia.org/wiki/Barycentric_coordinate_system_(mathematics)
L1=((y2-y3)(x-x3)+(x3-x2)(y-y3))/((y2-y3)(x1-x3)+(x3-x2)(y1-y3))
L2=((y3-y1)(x-x3)+(x1-x3)(y-y3))/((y3-y1)(x2-x3)+(x1-x3)(y2-y3))
L3=1-L1-L2
*/
bool InterpolationParameters(const CoordType & bq, ScalarType &a, ScalarType &b, ScalarType &c ) const
bool InterpolationParameters(const CoordType & bq, ScalarType &L1,
ScalarType &L2, ScalarType &L3 ) const
{
const ScalarType EPSILON = ScalarType(0.0001f);
ScalarType AreaGlobal=(P(1) - P(0)) ^ (P(2) - P(0));
ScalarType Area0=((P(2) - P(1)) ^ (bq - P(1)));
ScalarType Area1=((P(0) - P(2)) ^ (bq - P(2)));
ScalarType Area2=((P(1) - P(0)) ^ (bq - P(0)));
//ScalarType AreaGlobal=Area0+Area1+Area2;
/*if ((Area0>(AreaGlobal+EPSILON))||(Area1>(AreaGlobal+EPSILON))||(Area2>(AreaGlobal+EPSILON)))
return false;*/
a=Area0/AreaGlobal;
b=Area1/AreaGlobal;
c=Area2/AreaGlobal;
ScalarType x1=P(0).X();
ScalarType x2=P(1).X();
ScalarType x3=P(2).X();
///test inside/outside
if(((a>(ScalarType)1+EPSILON)||(b>(ScalarType)1+EPSILON)||(c>(ScalarType)1+EPSILON))||
((a<-EPSILON)||(b<-EPSILON)||(c<-EPSILON)))
return false;
///approximation errors
if(a>1)
a=(ScalarType)1;
if(b>1)
b=(ScalarType)1;
if(c>1)
c=(ScalarType)1;
if(a<0)
a=(ScalarType)0;
if(b<0)
b=(ScalarType)0;
if(c<0)
c=(ScalarType)0;
ScalarType y1=P(0).Y();
ScalarType y2=P(1).Y();
ScalarType y3=P(2).Y();
ScalarType x=bq.X();
ScalarType y=bq.Y();
return true;
L1=((y2-y3)*(x-x3)+(x3-x2)*(y-y3))/((y2-y3)*(x1-x3)+(x3-x2)*(y1-y3));
L2=((y3-y1)*(x-x3)+(x1-x3)*(y-y3))/((y3-y1)*(x2-x3)+(x1-x3)*(y2-y3));
L3=1-L1-L2;
bool inside=true;
inside&=(L1>=0-EPSILON)&&(L1<=1+EPSILON);
inside&=(L2>=0-EPSILON)&&(L2<=1+EPSILON);
inside&=(L3>=0-EPSILON)&&(L3<=1+EPSILON);
return inside;
}
///return the distance to the point q and neighors point p