arcbased

Arcbased is a term used in geometry and computer graphics to describe a modeling and rendering approach that represents curves and boundaries using circular arc primitives as the fundamental building blocks. It may refer to a methodology, a library, or a family of formats that encode shapes as sequences of arcs.

Core concepts: An arc primitive is defined by a center, radius, and start and end angles. Complex curves are approximated by chaining arcs with decisions about continuity and tangency. Operations such as rendering, intersection, offsetting, and boolean combinations are performed on arc sequences. Proponents cite exact representation of circular segments and predictable behavior for tangency.

Advantages: Exact circular segments can be represented without approximation error; potential performance benefits for certain rendering and intersection tests; robust numerical properties for arc-arc contacts. It can yield aesthetically pleasing contours with fewer segments for circular features compared to polylines.

Limitations: Not all curves are well-represented by arcs; many shapes require long sequences of small arcs, reducing simplicity. Converting between arc-based representations and conventional spline or polygon models can introduce complexity. Interoperability with existing graphics pipelines and file formats varies.

History and use: Arcbased concepts have appeared in CAD/CAM, vector graphics, and font design contexts, where circular features are common. Several experimental tools and libraries implement arc-based data structures or formats, sometimes in conjunction with other primitives, to balance fidelity and performance.

See also: circular arc, arc length, geometric modeling, vector graphics, spline, polyline.