refine2 without introducing additional border nodes about mesh2d HOT 6 CLOSED

@austinherrema Yes, there are some new options OPTS.REF1 and OPTS.REF2 that can be set to preserve (rather than the default refine) to preserve the boundary cells as you've specified them. Of course, this can lead to some potential compromises in terms of mesh quality constraints; specifically, it's not possible to guarantee that cells in the 'neighbourhood' of unrefinable boundary segments satisfy their requested bounds... In practice though, as long as your boundary discretisation matches the interior constraints reasonably well enough, you should get a good mesh that preserves an existing boundary.

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@dengwirda Thanks for the help. I updated mesh2d and tried to use the new OPTS.REF1 and OPTS.REF2 options (setting them both to preserve). Unfortunately, refine2 still appears to introduce new nodes. See the below figure, which shows a portion of the geometry for which I am generating a mesh. The input nodes are indicated by red markers.

Are there any other options I can change to achieve the desired behavior? Oddly, tweaking RHO2, SIZ1, and SIZ2 seems to have no effect on the final mesh.

Obviously the final mesh for this geometry will be quite odd if no new nodes are introduced, but this is acceptable for my application.

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@austinherrema I've had a chance to look into this, but am having trouble reproducing the behaviour you've shown. Can you email me the geometry, etc that you're specifying, along with details on the MATLAB / OCTAVE release that you're using?

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@dengwirda I sent an email; please let me know if you do not receive anything or need more info!

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@austinherrema Ah -- easy I think! MATLAB is case-sensitive, so opts.REF1 isn't quite the same thing as opts.ref1... (the lower-case version is what you're looking for here and seems to behave as expected I think).

I should perhaps change the error-checking that's done on the opts structure to catch these kind of cases with unrecognised fieldnames.

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@dengwirda Sure enough--using lowercase opts.ref1 and opts.ref2 produces the desired result. Thank you! I definitely should have tried that earlier, but I'm glad it was a straightforward solution.

For what it's worth, I think I used capitalized versions of the options because that is how they are presented in the refine2 help (OPTS.REF1 = {'REFINE'}, 'PRESERVE'...). Of course, I see now that that the capitalization was simply intended to set each option apart from its description.

Thanks for your great work on this tool!

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