Tagging cells

[donnaaboise]

Originally reported by: Donna Calhoun (Bitbucket: donnaaboise, GitHub: donnaaboise)

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If I tag a family of grids for coarsening, there is no need to then check to see whether any of the four sibling grids should be refined.

Is there a way I can determine whether a grid has been tagged for coarsening? I am thinking of a patch access function that returns 1/0 depending on the state of some internal flag.

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• Bitbucket: https://bitbucket.org/donnaaboise/forestclaw/issue/99

[donnaaboise]

Original comment by Donna Calhoun (Bitbucket: donnaaboise, GitHub: donnaaboise):

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Good suggestion. My main concern was keeping everything consistent, but with an assertion, this should be easy. Thanks.

[donnaaboise]

Original comment by Carsten Burstedde (Bitbucket: cburstedde, GitHub: cburstedde):

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In line with issue #96, this will likely be fastest using forestclaw patch data. Coarsening is called before refinement, and cb_regrid_tag4coarsening gets a pointer to all fine patches where it can set the will_coarsen flag in each one's user data. The subsequent call to cb_fclaw2d_regrid_tag4refinement can query this flag to avoid the virtual tagging function.

Care must be taken to set the flag to zero when a patch is created for the first time. Since patches are destroyed on coarsening, there should be no need to ever reset a flag from true to false (?). A good way to double-check this is to assert that the flag is false just before setting it to true in tag4coarsening.

[donnaaboise]

Original comment by Carsten Burstedde (Bitbucket: cburstedde, GitHub: cburstedde):

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I could program this fairly easily actually.

[donnaaboise]

Don't quite remember what the issue was, but assume it is fixed.