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["zengming" <>]

Hi, Tom

I have read the material you gave me, it help me a lot, thank you!

 

 

2009-03-06

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zengming

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发件人： Tom Kazimiers

发送时间： 2009-03-06  16:19:19

收件人：

抄送：

主题： Re: [cgal-discuss] how to output a point's coordinate

Hi zengming,

 

I have no experience with CGAL and intersection tests, but the manual

for intersection is located here:

http://www.cgal.org/Manual/3.4/doc_html/cgal_manual/Kernel_23_ref/Function_intersection.html#Index_anchor_323

 

Since intersections can be very different the intersection information

is stored in an CGAL::Object. To deal with this object you have to do an

object_cast <.. > - for example:

 

if (const Point_3 *ipoint = CGAL::object_cast <Point_3 >(&result)) {

// handle the point intersection case with *ipoint.

} else

if (const CGAL::Segment_2 <Spherical_k > *iseg =

CGAL::object_cast <CGAL::Segment_2 <Spherical_k >  >(&result)) {

// handle the segment intersection case with *iseg.

} else {

// handle the no intersection case.

}

 

Actually, I do not know of which type the intersection between spheres

is in CGAL - but again, the manual says to the intersection function you

use, that Object can have the following types:

 

- std::pair <Circular_arc_point_3 <SphericalKernel >, unsigned >, where the

unsigned integer is the multiplicity of the corresponding intersection

point,

- Circle_3 <SphericalKernel > or

- Type1, when Type1, Type2 and Type3 are equal, and if the three objets

obj1 and obj2 and obj3 are equal.

 

so I think you will have to make an if-then-else like above with those

possibilities for every Object in the vector.

 

Regards,

Tom

 

 

zengming schrieb:

> hi, everyone. I am fresh at cgal. how can I print the coordinate of a

> point?

> here is the test programe:

> #include  <CGAL/Exact_spherical_kernel_3.h >

> typedef CGAL::Exact_spherical_kernel_3 Spherical_k;

> typedef CGAL::Point_3 <Spherical_k > Point_3;

> typedef CGAL::Sphere_3 <Spherical_k > Sphere_3;

> int main() {

> Sphere_3 s1 = Sphere_3(Point_3(1.0,0.0,0.0), r);

> Sphere_3 s2 = Sphere_3(Point_3(-1.0,0.0,0.0), r);

> Sphere_3 s3 = Sphere_3(Point_3(0.0,0.0,1.0), r);

> std::vector < CGAL::Object  > intersecs;

> CGAL::intersection(s1, s2, s3, std::back_inserter(intersecs));

> std::cout < <intersecs.size() < <std::endl;

>

> Point_3 pt3;

> assign(pt3, intersecs[0]);

> //how can I output the coordinate of point pt3?

> return 0;

> }

> 2009-03-06

> ------------------------------------------------------------------------

> zengming

 

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