Oh, and now that I've noticed: please keep Cc:ing the mailing list;
the more helpful discussion that gets archived where future users'
search engines can find it, the better.
Thanks,
---
Roy
On Thu, 16 Nov 2017, Roy Stogner wrote:
On Wed, 15 Nov 2017, Zack Vitoh wrote:
Pure virtual functions (like those found in the PointLocatorBase and
related classes) were completely new to me earlier today, but I believe I
understand the proper syntax, at least, so if it's of use to anyone else,
here is an example of one way to use the PointLocatorBase class (to find
the element 'elem_ploc' containing (0,-0.5,0))
UniquePtr<PointLocatorBase>
my_point_locator(PointLocatorBase::build(TREE_ELEMENTS, mesh));
This should work, but it's not the most efficient way to go:
although PointLocatorTree::operator() is O(log N),
PointLocatorTree::build() is O(N), so you only get a fast amortized
lookup if you can reuse the same point locator over and over again.
Try
UniquePtr<PointLocatorBase> my_point_locator = mesh.sub_point_locator();
That will create a sub-locator which reuses the same main locator
instead of building a new one each time.
Real mpl_tol = 2.0 * diam;
my_point_locator->set_close_to_point_tol (mpl_tol);
my_point_locator->enable_out_of_mesh_mode();
I assume diam is an element diameter? Then you're trying to find
points as far as two diameters away from any current element? I'm
afraid that's not guaranteed to work - if you have quads or other
non-affine elements in your mesh, you can have mapping functions which
are invertible on the elements (so the mesh is perfectly valid) but
which become singular far away from the elements (so the
transformations we do when checking whether an element contains a
point become invalid). Beware.
Also, with a huge tolerance, you are going to have multiple elements
which "contain" a point, and the point locator may not return an
element which *actually* contains the point, even if one exists, if it
finds a merely close by element first.
const Elem* elem_ploc = my_point_locator->operator()( Point(0.,-0.5,0.) );
For operator(), terser syntax is:
const Elem* elem_ploc = (*my_point_locator)( Point(0.,-0.5,0.) );
Knowing the full ugly syntax is still useful, unfortunately, for
debugging with gdb...
---
Roy
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