FOSSIL Documentation

Appearance

FOSSILFOrtran Stereo Litography parser

A pure Fortran 2003+ OOP library for reading, writing, and manipulating STL mesh files.

Guide
API Reference
View on GitHub
📂

STL I/O

Load and save ASCII or binary STL files. Format is auto-detected; bad input (NaN/Inf coordinates) is rejected via a status code.

🔧

Surface Manipulation

Translate, rotate, mirror, resize, clip, and merge STL surfaces with a clean type-bound API.

🩺

Surface Analysis & Repair

Sanitize pipeline detects and fixes degenerate slivers, literal duplicates, disconnected edges, non-manifold edges, and inward-pointing normals. Predicates is_watertight / is_manifold / is_volume summarise the result.

📏

Signed Distance

Bit-exact closest-facet lookup via best-first traversal with d² pruning. Sign via Bærentzen–Aanæs pseudo-normal (default), ray intersection, or solid angle.

⚡

SAH BVH Acceleration

Binary BVH built with the surface-area heuristic — adapts to triangle density. ~100× faster distance queries than the legacy octree on dragon-scale meshes. Octree remains selectable.

🧪

OOP / TDD Designed

Two public types — surface_stl_object and facet_object — every public operation exercised by the regression suite.

🆓

Free & Open Source

Multi-licensed — GPLv3 for FOSS projects, BSD 2/3-Clause or MIT for commercial use. Fortran 2003+ standard compliant.

Quick start ​

Load an STL file, print its statistics, and translate it:

fortran
use fossil
use penf, only: R8P
use vecfor, only: ex_R8P

type(surface_stl_object) :: surface
real(R8P)                :: d

! Load (ASCII or binary, auto-detected) and run the full repair pipeline.
call surface%load_from_file(file_name='cube.stl', guess_format=.true.)
call surface%sanitize
print '(A)', surface%statistics()

! Signed distance — SAH BVH + pseudo-normal sign by default.
d = surface%distance(point=2.0_R8P * ex_R8P, is_signed=.true., is_square_root=.true.)
print '(A,ES12.5)', 'signed distance = ', d

! Translate and save.
call surface%translate(x=1.0_R8P, y=2.0_R8P, z=0.5_R8P)
call surface%save_into_file(file_name='cube-moved.stl')

Authors ​

Contributions are welcome — see the Contributing page.

Copyrights ​

FOSSIL is distributed under a multi-licensing system:

Use caseLicense
FOSS projectsGPL v3
Closed source / commercialBSD 2-Clause
Closed source / commercialBSD 3-Clause
Closed source / commercialMIT

Anyone interested in using, developing, or contributing to FOSSIL is welcome — pick the license that best fits your needs.