// distance [projX,projY,projZ] and (xx,yy,zz]
double d1= sqrt( (projX-xx)*(projX-xx) + (projY-yy)*(projY-yy) +(projZ-zz)*(projZ-zz) );
// distance [projX,projY,projZ] and (xx,yy,zz]
double d1= sqrt( (projX-xx)*(projX-xx) + (projY-yy)*(projY-yy) +(projZ-zz)*(projZ-zz) );