Forcelist

Forcelist is a data structure used in physics simulations and game engines to store multiple force contributions acting on a rigid body or particle. Each entry represents a single force and may include its vector, application point, duration or timestamp, and a label indicating the source. Forcelists enable modular accumulation of forces from different subsystems, such as gravity, collisions, propulsion, and environmental effects.

Most engines process a forcelist during a simulation step by summing the force vectors to produce the net force. Where applicable, the moment of each force about the body's center of mass is also accumulated to yield net torque. If an application point is unspecified, the force is assumed to act through the center of mass.

Common sources of forces include gravity, contact forces from collisions, spring or constraint forces, damping, user input, wind, buoyancy, and magnetic or electric forces in specialized simulations. Forcelists can distinguish persistent forces from transient impulses; impulses may be applied as instantaneous updates to velocity rather than as continuous forces.

Implementation considerations include data layout for performance, methods to add, remove, or clear entries, and thread safety in parallel simulations. Some systems also tag forces with identifiers to aid debugging or visualization. In practice, the forcelist is part of the broader physics integration pipeline that governs motion through Newton's laws. See also force, torque, vector, and physics engine.