Snap val for level-set discretization PMMG_snpval_ls

[laetitia-m]

WARNING not to be merged for now because:

• Not fully finished and tested yet - need to properly transfer data
• Need to have mmg PR#280 and ParMmg PR#123 merged to be able to test and merged this PR.
• Some parts of PMMG_snapval_ls function are copy-paste of MMG3D_snpval_ls function. Need to see if we can factorise the functions.
• Need to add ci tests

Creation of the snap value function PMMG_snpval_ls in file ls_pmmg.c when in LS mode.

[Algiane]

Sorry for the ongoing work. I commit the review to feed or remote discussions.

[Algiane]

Misunderstanding of the array content / index error: see #123 (comment)

I think that we have to do something as the following piece of pseudo-code:

alloc ( parmesh->int_node_comm );
memset ( parmesh->int_node_comm, 0 );

for (icomm=0; icomm<next_comm; icomm++) {
...
   for (i=0; i < nitem_ext; i++) {
      idx_ext = ext_comm->int_comm_index[i];
      val_max =  parmesh->int_node_comm [idx_ext];
      parmesh->int_node_comm [idx_ext] = MG_MAX ( val_max, MG_MAX(color_in, color_out)  ); 
   }

for ( i = 0; i<parmesh->ngrps; ++i ) {
   grp = parmhesh->grp[i];
   
   for ( k = 0; k<= grp->nitem_int_node_comm; ++k ) {
     ip = grp->node2int_node_comm_index1[k];
     pos_buf = grp->node2int_node_comm_index2[k];
     mesh->point[ip].s =  parmesh->int_node_comm[ pos_buf ];
   }
}

[laetitia-m]

Ok for the misunderstand - this has been modified accordingly.
By filling intvalues with point index ip

for( i = 0; i < grp->nitem_int_node_comm; i++ ){
    ip   = grp->node2int_node_comm_index1[i];
    idx  = grp->node2int_node_comm_index2[i];
    int_comm->intvalues[idx] = ip;
  }

Then, I still guess that what I was doing to find the proc owner is okay because only one group is allowed for PMMG_snpval_ls. (An assert has been added to ensure it assert(parmesh->ngrp == 1 && "more than one group per rank not implemented");)

[Algiane]

To check:

• What happens if the ls of one point is snapped by one of the neighbour (because it is in the interface+overlap but owned by the neighbour), another point is snaped by the current rank and both snap creates a non-manifold situation?
• I think that we are not abble to detect that without gathering the "snaped" points through all process a first time, then checking the manifoldness and then unsnapping the values and shared the unsnap info again ?

[laetitia-m]

Need to think about it to be sure I fully understand what you mean, but I think this case will be covered.

[codecov]

Codecov Report

Attention: Patch coverage is 88.32808% with 37 lines in your changes missing coverage. Please review.

Project coverage is 63.52%. Comparing base (c224b90) to head (4192277).

Files with missing lines	Patch %	Lines
src/ls_pmmg.c	62.50%	28 Missing and 5 partials ⚠️
src/overlap_pmmg.c	98.67%	1 Missing and 2 partials ⚠️
src/debug_pmmg.c	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #124      +/-   ##
===========================================
+ Coverage    63.14%   63.52%   +0.37%     
===========================================
  Files           46       47       +1     
  Lines        18962    19274     +312     
  Branches      3548     3610      +62     
===========================================
+ Hits         11974    12243     +269     
- Misses        6060     6088      +28     
- Partials       928      943      +15     

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