Twisted Eight

Twisted Eight

LiLit is a program to visualize functionals on freeform surfaces. It uses biquadratic g-splines to display surfaces and functions, which are defined by a control mesh for the surface and the function from some file in a special input format. It can run the Doo-Sabin subdivision algorithm on the control meshes, compute some surface integrals and handle trimmed surfaces. It also provides an iso line algorithm for the functions. As a special function it can display the curvature of the surface and reflection lines. There are also some scripts using simple input files to create surface and function control meshes.

LiLit has been developed as part of my diploma thesis “Visualization of Functionals on Freeform Surfaces”. It covers the concepts and algorithms used by LiLit and provides a large number of examples.

LiLit has been developed on a GNU/Linux system, but should also run on other UNIX systems if OpenGL/Mesa, lapack and blas are available.

The program can be freely distributed under the terms of the GNU General Public License.


The latest version of LiLit, the program developed for this thesis, is available in the software section. Version 0.2.1, also available in the software section has been used for the thesis itself.

Current releases of LiLit:

If you use this code please cite

  • F. C. Langbein. Visualisation of Functionals on Freeform Surfaces. Diploma thesis, Mathematical Institute A, 2nd Chair, Stuttgart University, May 1999. [Details]
Cite this page as 'Frank C Langbein, "LiLit," Ex Tenebris Scientia, 1st May 1999, [accessed 27th May 2019]'.

CC BY-NC-SA 4.0 This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.