CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

On 02/08/2012 03:41 PM, AdamMiller wrote:
> Thanks for the advice, but what I really want is an exact meridian vector
> for the CompareZatTheta_3 functor. I have a point on the meridian specified
> as a circular_arc_point_3 - which is not a vector.
>
> Comparison_result       
> fo (     SphericalKernel::Circular_arc_3 a0 , SphericalKernel::Circular_arc_3
> a1 , SphericalKernel::Vector_3 m )
>
> Do you have any advice?
Actually, this functions only works for a meridian which is rational.
What you can try it to convert the x and y coordinates of your points
into intervals (using CGAL::to_interval). Then out of this 2 intervals
you can extract two vectors (warning not necessarily inf_x,inf_y and 
sup_x,sup_y) which defines two meridians: one before, and one after the
one you are interested in. You can call the functor for one these two
meridians (if the result is the same then either they intersect 
in-between twice, or the order is correct).
If your arcs intersects, you might want to construct the intersection
points and check with Compare_theta_3 that none in between the two
meridians.


By curiosity, what are you using this for?

Sebastien.


> thanks again,
>
> Adam Miller
>
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