SGAL project

The Scene Graph Algorithms Library (SGAL) is a toolkit that supports the construction and maintenance of directed acyclic graphs that represent scenes and models in three-dimensional space. The toolkit consists of two libraries, namely SGAL and SCGAL, and an application, called player, which enables users to visualize the scene in an interactive manner. The player parses input files that describe the scene in a degenerate yet extended VRML format. The format is degenerate, as not all VRML features are supported (yet). However, it has been extended to support several new features. For example, it has been extended with several geometry node types, such as the Assembly node type, which represents assemblies or subassemblies; the AssemblyPart node type, which represents parts of assemblies; the SphericalGaussianMap node type, which represents (spherical) Gaussian maps of convex polytopes in 3D, and the ArrangementOnSphere, which represents arrangements of geodesic arcs embedded on the sphere. The extended format also supports, for example, a node type called ExactCoordinate, which represents exact coordinates, and enables the provision of exact rational coordinates as input. Each node object of the three types AssemblyPart, SphericalGaussianMap, and ArrangementOnSphere internally maintains the CGAL data structure that represents an arrangement of geodesic arcs embedded on the sphere.