【转帖】meaning of oddbsplinegetnurbsdata
 

meaning of oddbspline::getnurbsdata
meaning of oddbspline::getnurbsdata
i'm using oddbspline::getnurbsdata to get the knots of the spline curve. which is the meaning of the double array of the knots? can i use that values with getpointatparam() to find knots points?
why the methods oddnspline::getstartparam and oddbspline::getendparam() return always 0?
i'd like to pick some points on the curve starting from the point on start parm and ending with the point at end param; then dividing the param interval in some step and evaluate the points at any single step. is it possible?

oddbspline::getstartparam() & getendparam() return enotimplementedyet.
actually startparam is the first knot. endparam is the last knot.
if you need to convert oddbspline to polyline you can:
get nurbs data.
create odgenurbcurve3d object using nurbs data.
call odgenurbcurve3d::samplepoints() with specified tolerance (deviation). if zero deviation is specified some default depending on spline extents is used.
sergey slezkin

dividing parameter interval in some step and evaluating points isn't good idea for approximating spline by polyline.
the best way for approximating spline by polyline is:
1. create your odgiworlddraw and odgiworldgeometry inheritants. make function geometry() of your inheritant return link to your odgiworldgeometry inheritant. in case your aim is approximate spline by polyline, it will be better to use odgibasedrawobject as parent of your odgiworldgeometry inheritant.
2. call oddbspline::worlddraw() passing pointer to your odgiworlddraw inheritant as parameter.
you will receive polyline in your virtual oberride of odgibasedrawobject: olyline().
sincerely yours,
george udov