Question about AABB_tree_Triangle_3_soup and primitives

[Willie Maddox]

Hello,

I am trying to gain a better understanding of how the AABB_tree_Triangle_3_Soup works.  Consider the following python script:

#### triangle_tree_segment_intersection.py ####

#### BEGIN ####

from CGAL.CGAL_Kernel import Point_3, Triangle_3, Segment_3

def func(p,s):

    

    from CGAL.CGAL_AABB_tree import AABB_tree_Triangle_3_soup

    

    t = [Triangle_3(p[0],p[1],p[3]),Triangle_3(p[1],p[2],p[3])]

    tree = AABB_tree_Triangle_3_soup(t)

    intersections = []

    tree.all_intersections(s, intersections)

    for i in intersections:

        print 'The segment intersects primitive',i.second,'at the point(',i.first.get_Point_3(),')'

            

pa = [Point_3(0,0,0),Point_3(0,4,0),Point_3(4,4,0),Point_3(4,0,0)]

sa = Segment_3(Point_3(1,1,-1),Point_3(1,1,1))

func(pa, sa)

func(pa, sa)

pb = [Point_3(6,0,0),Point_3(6,4,0),Point_3(10,4,0),Point_3(10,0,0)]

sb = Segment_3(Point_3(7,1,-1),Point_3(7,1,1))

func(pb, sb)

#### END ####

This script returns the following:

The segment intersects primitive 0 at the point( 1 1 -0 )

The segment intersects primitive 2 at the point( 1 1 -0 )

The segment intersects primitive 4 at the point( 7 1 -0 )

My question is this:

Should python not destroy (garbage collect) the tree object when leaving the scope of func()? If so, why then do the primitives increment?

Thanks,

-Will

[Sebastien Loriot (GeometryFactory)]

Hi,

This is a bit hacky, there is an internal static counter
in the primitive class.

If you call t[0].reset_id() when you quit the function, it should be fine.

I don't see how I could make this automatic...

Sebastien.

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[Willie Maddox]

Sebastien,

Thank you for your quick response.

calling t[0].reset_id() at the end of the function throws an error:

Traceback (most recent call last):

  File "/home/maddoxw/workspace/CGAL_testing/src/triangle_tree_segment_intersection.py", line 24, in <module>

    test = func(pa, sa)

  File "/home/maddoxw/workspace/CGAL_testing/src/triangle_tree_segment_intersection.py", line 19, in func

    t[0].reset_id()

  File "/home/maddoxw/src/cgal-bindings/examples/python/CGAL/CGAL_Kernel.py", line 510, in <lambda>

    __getattr__ = lambda self, name: _swig_getattr(self, Triangle_3, name)

  File "/home/maddoxw/src/cgal-bindings/examples/python/CGAL/CGAL_Kernel.py", line 55, in _swig_getattr

    raise AttributeError(name)

AttributeError: reset_id

Suggestions?

-Will

[Sebastien Loriot (GeometryFactory)]

Sorry I overlooked the code. I added a workaround that is not
perfect but improves the situation.

git pull

and try

tree.reset_id()


Sebastien.

[Willie Maddox]

That seems to do it. You say the workaround is not perfect? How could it fail?

Thanks for the update!

On Friday, July 26, 2013 10:56:19 AM UTC-5, Willie Maddox wrote:

[Sebastien Loriot (GeometryFactory)]

Say you have two tree, the counter will be shared which can lead to unexpected behavior.

Sebastien.