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[Dr01TSPC <>]

I successfully meshed 2 co-centered spheres; with radii of 0.5 and 1.0; 
but the effort raised a question. Actually 2 questions.

Background:

I edited mesh_polyhedral_complex.cpp; treating the each sphere as a 
patch. 

The results depend up how I define "incident_subdomains", and ranged 
from segmentation fault, through mislabelled tets, to correctly labelled 
tets. By "correctly" labelled, I mean the tets in each subdomain have one 
id or "color".

So, I consider the labels: Outside=0, Larger sphere=1, Smaller sphere=2. To 
remind myself, I saved the surface mesh for the larger sphere in
patch-01.off,
and the surface mesh for the smaller sphere in patch-12.off.

RESULTS of varying incident_subdomains:

The following assignment works, in that the volume between the smaller and
larger 
spheres is red, while the volume in the smaller sphere is green.

const std::pair<int, int> incident_subdomains[] = {
  std::make_pair(1, 0),
  std::make_pair(2, 1),
}

The following results in a segmentation fault in the mesher:

const std::pair<int, int> incident_subdomains[] = {
  std::make_pair(0, 1),
  std::make_pair(2, 1),
};

The following also results in a segmentation fault in the mesher:

const std::pair<int, int> incident_subdomains[] = {
  std::make_pair(0, 1),
  std::make_pair(1, 2),
};

The following results in a mixture of green and red tets in the volume
between 
the smaller and larger spheres, while the test inside the smaller sphere 
are red.

const std::pair<int, int> incident_subdomains[] = {
  std::make_pair(1, 0),
  std::make_pair(1, 2),
};

So: Is there a description/explanation of how to assign input patches as 
boundaries between volumes? 

Is there a way to protect/freeze the surface meshes, so that I know they 
are the same (node numbers and positions) on output?

Thanks,
Tim

BTW: Per a Stack Overflow discussion from ~Sept. 11, I print the output 
mesh file using:

c3t3.output_to_medit(medit_file, false, true)





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