  collision detection typically refers to the computational problem of detecting the intersection of two or more objects. while the topic is most often associated with its use in video games and other physical simulations, it also has applications in robotics. in addition to determining whether two objects have collided, collision detection systems may also calculate time of impact (toi), and report a contact manifold (the set of intersecting points).ericson, christer. real-time collision detection. elsevier, 2005, p. 13. collision response deals with simulating what happens when a collision is detected (see physics engine, ragdoll physics). solving collision detection problems requires extensive use of concepts from linear algebra and computational geometry. == overview == right|200px|thumb|billiards balls hitting each other are a classic example applicable within the science of collision detection. in physical simulation, we wish to conduct experiments, such as playing billiards. the physics of bouncing billiard balls are well understood, under the umbrella of rigid body motion and elastic collisions. an initial description of the situation would be given, with a very precise physical description of the billiard table and balls, as well as initial positions of all the balls. given a force applied to the cue ball (probably resulting from a player hitting the ball with his or her cue stick), we want to calculate the trajectories, precise motion, and eventual resting places of all the balls with a computer program. a program to simulate this game would consist of several portions, one of which would be responsible for calculating the precise impacts between the billiard balls. this particular example also turns out to be ill conditioned: a small error in any calculation will cause drastic changes in the final position of the billiard balls. video games have similar requirements, with some crucial differences. while physical simulation needs to simulate real-world physics as precisely as possible, video games need to simulate real-world physics in an acceptable way, in real time and robustly. compromises are allowed, so long as the resulting simulation is satisfying to the game players. == collision detection in physical simulation == physical simulators differ in the way they react on a collision. some use the softness of the material to calculate a force, which will resolve the collision in the following time steps like it is in reality. due to the low softness of some materials this is very cpu intensive. some simulators estimate the time of collision by linear interpolation, [[rollback (data management)|roll b
Computational_physics Computer_physics_engines Video_game_development