A CAD application can expose hundreds of modeling commands, but many of them eventually reduce to a smaller set of demanding geometric computations. Creating an extrusion, subtracting one body from another, offsetting a surface, or adding a fillet requires precise manipulation of mathematical geometry and the topology that connects it. For developers building engineering software, understanding this modeling layer is essential because its behavior influences application architecture, model reliability, and the features that can be implemented above it.
A Kernel Works Below the Feature Level
Users typically think in terms of engineering features: holes, pockets, ribs, chamfers, shells, or patterns. A modeling engine works at a lower level.
It deals with points, vectors, curves, surfaces, edges, faces, shells, and bodies. Application code translates user intent into operations on these entities.
Consider a simple extrusion. The application may define a closed sketch and an extrusion distance. The geometric kernel must construct the required surfaces, determine their boundaries, create the associated topology, and produce a valid body.
