VTKFortran

Pure Fortran VTK XML API

a pure Fortran 2003+ OOP library for writing and reading files conforming the VTK XML standard.

📐 VTK Topologies Rectilinear (.vtr), Structured (.vts), and Unstructured (.vtu) grids; composite multi-block (.vtm) and parallel partitioned (.pvts) datasets	🗜️ Output Formats ASCII, Base64-encoded binary, and raw binary appended	⚡ Parallel Safe Thread and processor safe — multiple files can be written concurrently under OpenMP or MPI	🎨 OOP Design Polymorphic xml_writer allocated at runtime; vtk_file, pvtk_file, vtm_file expose a clean type-bound-procedure API
🔢 All Numeric Kinds All PENF kinds (I1P–I8P, R4P–R8P) and array ranks 1–4 supported in data arrays	✅ Error Codes Every procedure returns an integer error code — zero means success	🔓 Multi-licensed GPL v3 · BSD 2/3-Clause · MIT	📦 Multiple build systems CMake, FoBiS.py, fpm, Make

Documentation

For full documentation (guide, API reference, usage examples, etc.) see the VTKFortran website.

---

Authors

• Stefano Zaghi — @szaghi

Contributions are welcome — see the Contributing page.

Copyrights

This project is distributed under a multi-licensing system:

• FOSS projects: GPL v3
• Closed source / commercial: BSD 2-Clause, BSD 3-Clause, or MIT

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

---

Quick start

use vtk_fortran, only : vtk_file
use penf,        only : I4P, R8P
implicit none
type(vtk_file)     :: a_vtk_file
integer, parameter :: nx1=0, nx2=9, ny1=0, ny2=5, nz1=0, nz2=5
integer, parameter :: nn=(nx2-nx1+1)*(ny2-ny1+1)*(nz2-nz1+1)
real(R8P)          :: x(nx1:nx2,ny1:ny2,nz1:nz2)
real(R8P)          :: y(nx1:nx2,ny1:ny2,nz1:nz2)
real(R8P)          :: z(nx1:nx2,ny1:ny2,nz1:nz2)
real(R8P)          :: v(nx1:nx2,ny1:ny2,nz1:nz2)
integer            :: error

error = a_vtk_file%initialize(format='binary', filename='output.vts', &
                              mesh_topology='StructuredGrid',          &
                              nx1=nx1, nx2=nx2, ny1=ny1, ny2=ny2, nz1=nz1, nz2=nz2)
error = a_vtk_file%xml_writer%write_piece(nx1=nx1, nx2=nx2, ny1=ny1, ny2=ny2, nz1=nz1, nz2=nz2)
error = a_vtk_file%xml_writer%write_geo(n=nn, x=x, y=y, z=z)
error = a_vtk_file%xml_writer%write_dataarray(location='node', action='open')
error = a_vtk_file%xml_writer%write_dataarray(data_name='pressure', x=v, one_component=.true.)
error = a_vtk_file%xml_writer%write_dataarray(location='node', action='close')
error = a_vtk_file%xml_writer%write_piece()
error = a_vtk_file%finalize()

See src/tests/ for more examples covering rectilinear, unstructured, multi-block, parallel, and volatile XML output.

---

Install

CMake

Clone, build, and test:

git clone https://github.com/szaghi/VTKFortran --recursive
cd VTKFortran
cmake -S . -B build -DBUILD_TESTING=ON
cmake --build build && ctest --test-dir build

As a subdirectory dependency — place a recursive clone alongside your sources and add to your CMakeLists.txt:

add_subdirectory(VTKFortran)
target_link_libraries(your_target VTKFortran::VTKFortran)

FoBiS.py

git clone https://github.com/szaghi/VTKFortran --recursive && cd VTKFortran
FoBiS.py build -mode static-gnu   # static library
FoBiS.py build -mode tests-gnu    # build and place tests in ./exe/
bash scripts/run_tests.sh         # run tests

fpm

Requires at least version v0.13.0!

Building library in current directory

fpm build --compiler gfortran/ifx/... --profile release

The library may be installed to a custom location with

fpm install --compiler gfortran/ifx/... --profile release --prefix /target_path

Please refer to the fpm.toml file for further available profiles and features.

GNU Make

make