The MeshLink Library provides mesh-geometry associativity in an open, geometry kernel neutral, framework. The library is written using the C++ object-oriented programming model, but bindings for C, FORTRAN, and Python 3 languages are also available.

The public API was designed with a mesh-centric focus as that is the common natural language of third-party simulation software systems. The MeshLink API provides a common interface for creating, modifying, and querying geometry-mesh associativity using mesh nomenclature.

The MeshLink Schema was developed as part of NASA Contract 80NSSC18C0109.

The MeshLink Library was developed as part of U.S. Air Force Contract FA9101-18-P-0042.

The term geometry association is used to denote the relationship between a mesh element and the supporting computational geometry used to constrain the location of the mesh element in Cartesian space.

Mesh-geometry associativity is defined by the mesh generation software in the MeshLink XML file. The MeshLink XML file utilizes the MeshLink Schema (XSD) to link mesh elements to geometry elements in an application defined manner. An example implementation of MeshLink XML file export has been added to Pointwise version 18.3R1.

Mesh associativity to the geometry is defined in terms of mesh elements within mesh topology containers.

Mesh topology refers to 1D, 2D, and 3D constructs within the mesh heirarchy.

Mesh String: A 1D collection of mesh edges. A Mesh String may reference one or more geometry curves.

Mesh Sheet: A 2D collection of mesh faces. A Mesh Sheet may reference one or more geometry surfaces.

Mesh Model: A 3D mesh volume. A Mesh Model is a container for Mesh String and Mesh Sheet elements used in the definition of the volume mesh.

The MeshLink Library is meant to be compatible with a number of 3rd party geometry kernels. Only a few basic of functions must be supported by a geometry kernel in order to be useful for computational work with MeshLink. A geometry kernel must be able to read the geometry data file and to support computational evaluations on the geometric entities contained in the file. Typical computational operations are closest point projection and parametric evaluation.

New in MeshLink v1.1 is the ability to write a MeshLink XML file. This provides an application the ability to read and process mesh and geometry files and update the associativity as needed. Mesh that has been adapted can then be re-used later by the same or other MeshLink-aware applications without the need to re-do transformitive mesh operations.

The following are required to build and run the MeshLink library:

• C++ compiler

• XML parser

  • Apache Xerces example provided

• 3rd party geometry kernel

  • Reference implementation built and tested with Project Geode.

The MeshLink Library consists of the main API in the src/meshlink directory and the reference MeshLink XML file parser implementation in src/mlparser_xerces and the reference geometry kernel implementation in src/mlkernel_geode.

Makefiles for Linux and Mac OSX and Microsoft Visual Studio project files are provided for the x86_64 architecture.

An example build procedure:

cd <path_to_src_dir>/meshlink
make -f Makefile.<platform> BUILD=Release

cd <path_to_src_dir>/mlparser_xerces
make -f Makefile.<platform> BUILD=Release

cd <path_to_src_dir>/mlkernel_geode
make -f Makefile.<platform> BUILD=Release

To build the MeshLink library and Xerces parser implementation on Windows with Visual Studio 2017:

cd <path_to_src_dir>/meshlink
devenv meshlink.sln /build "LibraryRelease|x64"

Test harness applications are provided for C++ (app/harness_cpp), C (app/harness_c), and FORTRAN (app/harness_f) bindings.

Makefiles for Linux and Mac OSX and Microsoft Visual Studio project files are provided for the x86_64 architecture.

The src directory contains a top-level Makefile with targets for building the test applications and executing the test on Linux and Mac OSX platforms. Note that all test harnesses require access to the Geode geometry kernel (not provided).

To build a harness and execute the test:

cd <path_to_src_dir>
make BUILD=Release test_harness_cpp

To build all the Geode/Xerces test harnesses on Windows with Visual Studio 2017:

cd <path_to_src_dir>/meshlink
devenv meshlink.sln /build "GeodeTestRelease|x64"

A successful test will parse the example MeshLink XML file and print details of the loaded mesh-geometry associativity data. If building with the Pointwise Project Geode geometry kernel, additional tests of the computational geometry access routines will be performed.

• Project Geode
• Apache Xerces
• Python 3
• XML Schema