Which form of solid modeling represents a shape by a set of mathematical functions?

• A. Boundary Representation (B-Rep)
• B. Constraint Boundary Illustration (CBI)
• C. Constructive Solid Geometry (CSG)
• D. Bound Framework Construction (BFC)

Answer: (C)

Constructive Solid Geometry is the one that builds a shape from simple, well-defined pieces using boolean operations. In this approach you start with primitive solids like a box, a sphere, or a cylinder, each described by straightforward mathematical definitions. You then combine them with operations such as union, intersection, and difference to form more complex shapes. The model is essentially a constructive description: a structured combination of mathematical primitives and operations, often depicted as a tree of operations.

This is different from boundary representation, which defines a solid by its surface boundaries (the faces, edges, and vertices) rather than by a constructive equation or function set. The other terms aren’t standard ways to describe solid models in this context, so they don’t capture the idea of building a shape through a set of mathematical operations on primitives.