Crate stripack_sys 

Raw Rust FFI bindings to STRIPACK.

This crate provides low-level unsafe bindings to STRIPACK, a Fortran library for constructing Delaunay triangulations and Voronoi diagrams on the surface of the unit sphere.

Overview

STRIPACK (Algorithm 772) computes Delaunay triangulations and Voronoi diagrams of a set of nodes on the surface of the unit sphere. The algorithms are generalizations of Robert Renka’s TRIPACK software for the plane.

This -sys crate provides direct FFI bindings to the underlying Fortran routines.

Building

This crate requires a Fortran compiler to build the bundled STRIPACK library:

• Arch Linux: pacman -S gcc-fortran
• Ubuntu/Debian: apt install gfortran
• macOS: brew install gcc

Safety

All functions in this crate are unsafe because they:

• Work with raw pointers
• Call into Fortran code with different calling conventions
• Require the caller to ensure proper memory allocation and alignment
• May have undefined behavior if preconditions are not met

Users must ensure:

• Arrays are properly sized (e.g., list[6*(n-2)], lptr[6*(n-2)], lend[n])
• Pointers are valid and properly aligned
• Nodes are unit vectors (x² + y² + z² = 1)
• Indices are 1-based (as per Fortran convention)

Data Structure

The triangulation is represented using a linked list data structure:

• list: Adjacency lists
• lptr: Pointers within list
• lend: Pointers to ends of adjacency lists
• lnew: Pointer to first empty location

Refer to the individual function documentation for details on array sizes and conventions.

Example

use stripack_sys::ffi::*;

// Create a simple tetrahedral triangulation with 4 nodes
let n = 4;
let x = vec![1.0, 0.0, 0.0, 0.0];
let y = vec![0.0, 1.0, 0.0, 0.0];
let z = vec![0.0, 0.0, 1.0, 1.0];

let mut list = vec![0; 6 * (n - 2) as usize];
let mut lptr = vec![0; 6 * (n - 2) as usize];
let mut lend = vec![0; n as usize];
let mut lnew = 0;
let mut near = vec![0; n as usize];
let mut next = vec![0; n as usize];
let mut dist = vec![0.0; n as usize];
let mut ier = 0;

unsafe {
    trmesh(
        &raw const n,
        x.as_ptr(),
        y.as_ptr(),
        z.as_ptr(),
        list.as_mut_ptr(),
        lptr.as_mut_ptr(),
        lend.as_mut_ptr(),
        &raw mut lnew,
        near.as_mut_ptr(),
        next.as_mut_ptr(),
        dist.as_mut_ptr(),
        &raw mut ier,
    );
}

assert_eq!(ier, 0);

License

The Rust bindings are licensed under MIT OR Apache-2.0 at your option.

The bundled Fortran code is distributed under the GNU LGPL.

Attribution

STRIPACK — Delaunay Triangulation and Voronoi Diagram on the Surface of a Sphere

• Original author: Robert J. Renka, University of North Texas
• Reference: R. J. Renka, “Algorithm 772: STRIPACK: Delaunay Triangulation and Voronoi Diagram on the Surface of a Sphere”, ACM Transactions on Mathematical Software, Vol. 23, No. 3, September 1997, pp. 416-434.
• DOI: https://doi.org/10.1145/275323.275329

The Fortran 90 version used in this crate was prepared by John Burkardt and is distributed under the GNU LGPL.

Modules

ffi