A physics engine is software that mimics the laws of physics. It gives virtual objects Force and momentum, calculating their movement and Collision with other elements. This creates believable interactions, from tumbling blocks to flowing fluid, vital for Video Game and Simulation fidelity.
At its core, physics engines utilize Kinematics to describe the motion of objects without considering the forces causing that motion. This involves calculating position, velocity, and acceleration. More advanced applications use Inverse Kinematics, where the desired end position of a body part (like a character's hand) is specified, and the engine calculates the required joint rotations to achieve it, simplifying Animation and often seen in robotics.
Another crucial aspect is Constraint Solving. Constraints are rules that limit the movement or relationship between objects, such as keeping two objects attached by a joint, preventing penetration, or defining a specific range of motion. The engine continuously solves these constraints to maintain physical realism and prevent objects from behaving unnaturally.
While Kinematics provides the fundamental description of motion, and Inverse Kinematics aids in controlling complex articulated body for Animation, Constraint Solving acts as the enforcement mechanism. It ensures that the calculated movements and poses — whether derived from forces or specific kinematic goals — consistently adhere to the defined physical rules and interactions, preventing unrealistic outcomes and making the simulated world believable.
