Character hit reaction animations using physics and inverse kinematics

Character hit reaction is an inherent component in game development. Natural hit reactions in games are typically achieved through the use of artist‐created hit animations and motion capture. To improve the realism of impact reactions, game developers combine physics simulation with distinct hit animations based on character statuses. However, there is currently no method that can automatically produce hit reactions based on hit information in game development. To this end, we propose a physics‐driven inverse kinematic method for generating character reaction animations. We postulate that a character's hit reactions are the result of an assault impulse spreading throughout the body and forcing the body to move. Five IK (inverse kinematics) solvers are used to control character poses. Each IK solver is used to control the movement of a different part of the body. The IK solvers, which are used to determine the positions of various bodily parts, are driven by unconstrained physics simulation. Furthermore, physics simulation with constraints is used to fine‐tune the character's movements. Experiment results show that our method outperforms Unreal Engine‐based hit animation and physics simulation. This paper presents a novel approach to real‐time character hit reaction based on physics simulation and inverse kinematics. We use an impulse spread algorithm to distribute assault impulses to body parts, and then we use five inverse kinematics solvers to control the positions and poses of body parts. We also use constrained physics simulation to fine‐tune character movements. Experiment results show that our method can generate more natural and diverse hit reaction animations.