【转帖】odgecircarc2d tangen
 

odgecircarc2d tangent
odgecircarc2d tangent
the samplepoints() of a tangent (odgeline2d) to odgecircarc2d is returned null.
what is the data present in m_point1, m_point2 of a tangent (odgeline2d) ? can anybody explain...
i have same problem

hi,
tangent of circle is odgeline2d object. odgeline2d is infinite line. it hasn't start and end. it has only point and direction. so if you ask getsamplepoints(int numsample, odgepoint2darray& pointarray),
it return nothing due to odgeline hasn't bounds.
toolkit has odgeline2dseg object - it has start and end point. it is segment representation, but odgeline2d is line representation.
code:
bool odgecircarc2d::tangent(const odgepoint2d& pnt, odgeline2d& line, const odgetol& tol) const
{
if(!odequal(pnt.distanceto(m_pcenter), radius(), tol.equalpoint()))
return false;
odgevector2d v = pnt - m_pcenter;
v.rotateby(odapi2); // anyway, cw or ccw
line.set(pnt, v);
return true;
}
bool odgecircarc2d::tangent(const odgepoint2d& pnt, odgeline2d& line, const odgetol& tol, odgeerror& error) const
{
odgevector2d v = pnt - m_pcenter;
double l = v.length();
if(odequal(l, radius(), tol.equalpoint()))
{
v.rotateby(odapi2); // anyway, cw or ccw
line.set(pnt, v);
error = odge::karg1onthis;
return true;
}
error = ( l < radius() ) ? odge::karg1insidethis : odge::karg1toobig;
return false;
}