TinySpline: A Small, yet Powerful Library for Interpolating, Transforming, and Querying NURBS, B-Splines, and Bézier Curves

Abstract

NURBS, B-Splines, and Bézier curves have a wide range of applications. One of them is software visualization, where these kinds of splines are often used to depict relations between objects in a visually appealing manner. For example, several visualization techniques make use of hierarchical edge bundles to reduce the visual clutter that can occur when drawing a large number of edges. Another example is the visualization of software in 3D, virtual reality, and augmented reality environments. In these environments edges can be drawn as splines in 3D space to overcome the natural limitations of the two-dimensional plane - e.g., the collision of edges with other objects. While Bézier curves are supported quite well by most UI frameworks and game engines, NURBS and B-Splines are not. Hence, spline-based visualizations are considerably more difficult to implement without in-depth knowledge in the area of splines.In this paper we present TinySpline, a general purpose library for NURBS, B-Splines, and Bézier curves that is well suited for implementing advanced edge visualization techniques - e.g., but not limited to, hierarchical edge bundles. The core of the library is written in ANSI C with a C++ wrapper for an object-oriented programming model. Based on the C++ wrapper, auto-generated bindings for C#, D, Go, Java, Lua, Octave, PHP, Python, R, and Ruby are provided, which enables TinySpline to be integrated into a large number of applications.