hardsphere

Hardsphere is a term used in computer graphics and physics simulations to represent an object as a perfect, solid sphere with no internal structure or deformation. In this model, the sphere's surface is infinitely rigid, meaning it cannot be compressed, stretched, or otherwise altered by external forces. Collisions involving hardspheres are typically calculated by determining if the distance between the centers of two spheres exceeds the sum of their radii. If it does, a collision has occurred.

The hardsphere model is a simplification that makes collision detection and response computationally efficient. It is often employed in scenarios where the precise physical behavior of deformable objects is not critical, such as in early video games, simple physics engines, or as a placeholder for more complex objects. For instance, in a game simulating billiard balls, each ball can be treated as a hardsphere. When two hardspheres collide, their velocities are updated based on principles of elastic collision, assuming no energy is lost.

While computationally advantageous, the hardsphere model has limitations. It cannot accurately represent phenomena like bouncing that involves compression and deformation, such as a rubber ball hitting a surface. It also does not account for surface properties like friction or elasticity beyond simple reflection. More complex simulations often utilize models that allow for deformation, such as softbodies or finite element methods, to achieve greater realism. Despite its simplicity, the hardsphere remains a fundamental concept in introductory physics and computer graphics due to its ease of implementation and understanding.