Matt

In my notion, there are no cells, only vertices. Or if you want to renaming things, then there are only cells, no vertices, but the fine a coarse grid cells do not share faces.

To answer your question specifically: no, it does not matter whether  the centre of a "cell" is selected. Only the vertices that are selected should be part of the selection.

-erik

On Wed, Nov 11, 2015 at 8:57 AM, Matthew Turk wrote:
Hi Erik,

how to regard "vertices" as separate from "cells", or if they should
not be.  In terms of things like visualization, vertex centered data
is not a huge leap in functionality, but in terms of data selection we
need to be careful.  The canonical question is, if you have a region
selector that includes the *center* of a zone, should all of its
vertices be selected?  For instance, imagine you have a region
selector whose corner resides at the center of a (3D) cell.  Does one
select all eight vertices, since the "cell" is nominally selected, or
just the one vertex that is included?  If we can answer that, we can
start the work of implementing.

On Tue, Nov 10, 2015 at 7:11 PM, Nathan Goldbaum <nathan12343@gmail.com> wrote:
>
>
> On Tuesday, November 10, 2015, Erik Schnetter <schnetter@gmail.com> wrote:
>>
>> I have implemented a front-end for cell-centred Cactus AMR data.
>>
>
> Awesome! We'd love to have this in the public distribution of yt.
>
>>
>>
>> However, many Cactus simulations use vertex-centred AMR. That is, data is
>> stored at the vertices of a grid (not in the cells), and coarse vertices are
>> at the same locations as fine vertices.
>>
>> How do I present such data to yt? Do I need to set grid coordinates
>> differently, or is there a "vertex centred" flag?
>>
>> When vertex-centred data are displayed, then I expect either a "control
>> volume" around each vertex to have the same value, or to use e.g. linear
>> interpolation in the cells from the respective boundaries.
>
>
> We don't have good support for vertex-centered AMR data. I think Matt would
> have a better idea of what approaches we might take here.
>
>>
>>
>> -erik
>>
>> --
>> Erik Schnetter <schnetter@gmail.com>
>> http://www.perimeterinstitute.ca/personal/eschnetter/
>
>
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