public PointOnPath AdvancePoint(PointOnPath pt, ref double dist)
{
// assert that we're looking at the same segment
Debug.Assert(Equals(pt.segment));
if (pt.dist + dist <= 0)
{
// handle the case of negative distance going before start point
dist += pt.dist;
return(StartPoint);
}
else if (pt.dist + dist >= cb.ArcLength)
{
// handle the case of positive distance going after end point
dist -= cb.ArcLength - pt.dist;
return(EndPoint);
}
else
{
// we're in the range that we can achieve
double targetDist = pt.dist + dist;
double tValue = cb.FindT(targetDist);
double actDist = cb.PartialArcLength(tValue);
dist = 0;
return(new PointOnPath(this, targetDist, cb.Bt(tValue)));
}
}