FreeSG ("Free" as in "Free software" and "Free of bloat") is an compact, general-purpose, open-source scene-graph library. It implements a generic, extensible object/scene representation, designed to simplify such tasks as real-time rendering and geometrical queries. One feature which distinguishes FreeSG from the variety of scene-graph libraries available is its ability to solve systems of logical (geometrical) constraints such as angles and distances, in order to define the relationship between elements of a scene, in a powerful and unambiguous way.

FreeSG depends on the Agar library, and it released under the same revised BSD license. FreeSG and its related projects are sponsored by Csoft.net: Security conscious, high-availability Unix hosting on redundant server arrays.

FreeSG is currently under development. The sources are available via via Subversion.

The FreeSG distribution includes three libraries: SG (3D scenes), SK (2D sketches) and MAP (tiling).

SK Library The SK ("sketch") library provides support for dimensioned 2D vector drawings (or sketches). This includes an Agar-GUI widget for visualization and edition of sketches. The constraint solving system greatly improves the efficiency of the user interface, and enables dimensions to be specified in a parametric fashion.

SG Library The SG ("scene graph") library aims at implementing a set of efficient, generic scene rendering / geometrical query algorithms where the speed and memory tradeoffs can be adjusted to the widest possible range of applications and platforms. Using a simple, extensible scene description language, applications using SG can create hierarchical scenes composed of objects (e.g., polyhedrons, viewpoints, light sources). The relationship between those objects can be expressed in terms of standard transformation matrices, or geometrical constraints.

"The idea is if you use those two shapes and try to colour the plane with them so the colours match, then the only way you can do this is to produce a pattern which never repeats itself." -- Roger Penrose