The Spore creatures, likewise, used Metaballs, a geometry creation algorithm that could create smooth tubes along paths in 3D space. Other algorithms for filling spaces and paths are Voronoi patterns, Perlin/Simplex noise, triangulation algorithms, 3D extrusion or rotation, and the Diamond-square algorithm for fractal terrain. These algorithms are particularly well-suited for interactive generators, because the user can provide the input parameters for the generator.
Strasheela is a highly expressive constraint-based music composition system.2 The Strasheela user declaratively states a music theory and the computer generates music which complies with this theory. A theory is formulated as a constraint satisfaction problem (CSP) by a set of rules (constraints) applied to a music representation in which some aspects are expressed by variables (unknowns). Music constraint programming is style-independent and is well-suited for highly complex theories (e.g. a fully-fledged theory of harmony). User-interface is the programming language Oz. The results can be output into various formats including MIDI, Csound, and Lilypond.