TetGen

TetGen is a general-purpose tetrahedral mesh generator for three-dimensional domains. Developed by Hang Si, it is distributed as open-source software and is available as both a standalone command-line program and a C/C++ library that can be embedded into applications. The input describes a 3D domain as a piecewise linear complex, consisting of vertices, straight edges, and triangular facets that form the boundary of the domain. TetGen can generate conforming tetrahedral meshes for such domains and can handle interior features and sharp edges through constraint handling.

The core algorithm combines constrained Delaunay tetrahedralization with post-processing to produce high-quality meshes. TetGen can enforce constraints via constrained Delaunay tetrahedralization (CDT) to respect input boundaries and features. It provides mesh quality and size controls, allowing users to specify constraints such as a maximum tetrahedron volume or a minimum radius-edge ratio, and to refine the mesh to target densities. The result is a tetrahedral mesh that adheres to the domain geometry while aiming to maximize element quality.

Output from TetGen includes the coordinates of mesh nodes and the indices of tetrahedra, with optional boundary and neighbor information. The software is commonly used in finite element analysis, computational fluid dynamics, geophysics, and computer graphics, serving both as a practical meshing tool and as a reference implementation for 3D tetrahedralization methods. TetGen has been cited widely in the literature and remains a widely used resource for robust 3D mesh generation.