Normalize the triangle dependency

[Dave-Allured]

The objective is simplifying the NCL build and install process, especially as relates to package management software.

NCL uses the triangle software package for some triangular mesh calculations. The current source build instructions are complicated and unusual by normal package standards:

• Copy triangle source code distribution files into an NCL source subdirectory.
• Triangle is then compiled and built into the NCL executable as if it was part of the NCL code base. In the middle, the object file triangle.o is used in a similar way to conventional library files.

I suggest converting to a simpler and more conventional system:

• Build, install, and manage triangle as an external package, like most of the other NCL dependencies.
• Ensure that triangle's "library build" option is enabled. This will generate a library file, something like libtriangle.so or libtriangle.dylib.
• Now NCL will use a normal procedure for external library linkage, like other dependencies.

I took a quick look at NCL source code referring to triangle. The interface to this package is very simple. It appears that this request would require only minor changes to NCL's C source code and build files.

Triangle including libtriangle is now available as an external package from various open source repositories such as Debian and Macports.

[erogluorhan]

Hi @Dave-Allured , thanks a lot for this suggestion!

NCL is currently in maintenance mode, where the GeoCAT team provides support for periodic bug-fixing releases for critical bugs as well as Conda installation-related questions/issues (Please check the NCL website for maintenance-mode related community announcements). For your build-from-source suggestion, you may consider writing to the email groups ncl-talk and ncl-install for seeking potential support of the NCL user community.

Thanks!

Orhan @ GeoCAT