Over past few Years there is a boom in Gaming industry, we have seen and played some most anticipated games which have enlightened us not just because of their astonishing Graphics but due to their gameplay as well, and physics Engine has a vital role in the success of a game. Some of the popular game titles are FIFA, PES, Half Life, Portal, Crysis, Halo, Split second, Need for Speed, Batman, GTA,Call of Duty, and Battle field. If you have played these kind of games then you must have experienced the real world simulation in many aspects, Like cloth simulation, water and smoke simulation, collisions , Building destruction etc.
Before proceeding any further lets look at the definition of a physics engine as per Wikipedia which states a physics engine is a computer software that provides an approximate simulation of certain physical systems, such as rigid body dynamics (including collision detection), soft body dynamics, and fluid dynamics, of use in the domains of computer graphics, video games and film.
lets get in to details of a physics engine used in games today, As a Gamer we all want to experience a real world simulation and physics in games. But we don't want to wait for a physics simulations to happen we want everything that enrich our experience in real time. Weather its a crashing plane, a colliding car or a collapsing building we love to destroy stuff in games. Well everyone want to feel powerful (Only if destroying things could save our world :P)
How it works-
In games most objects interact with each other like they do in real world not completely accurate but providing a perceptually correct approximation , In real world Its because of presence of certain forces and and energy forms due to which we see the physics play its part in nature, like falling objects due to gravity, recoil of gun after shooting due to Newtonian forces and so on. But in a game developers have to take different approaches to simulate these behaviors.
In games 3d objects are assigned as rigid bodies and interact with player and environment as per their dynamic and static properties. Lets take an example of a 3d pool game, where all balls will have a invisible sphere collider to represent the balls to physics engine which will then treat balls as a sphere. Pool table and cue stick are static objects but Cue stick can be controlled by player to initiate simulation. In this example we have variety of actions lead to different physics simulations like Newtonian forces collisions, Gravity pull, friction and kinetic energy. Different value of each property of ball will result a different simulation each time. Its a very simple example of approximate physics used in a 3d game. This kind of physics calculation is fast and can be done for simple objects like box cylinder and sphere.
Where as Modern games have more complex meshes which takes different approach to simulate physics which is called Finite element based system it generally creates a 3 dimensional volumetric tessellation of 3d object having all physical properties which on simulation calculate the stress within the 3d object to drive
Deformation, fracture and other physical effects with a realistic simulation.
There is one more physics simulation used for character interaction with another character which is ragdoll physics, A ragdoll physics creates animation procedurely according to the impact and forces applied to a character, A ragdoll system treats a character bones as rigid bodies and joints as hinges and therefore drives a unique animation of collapsing as per defined by the developers, Early when this system was not developed Developers use a predefined animation for particular situations like death or falling.There are advance system available for more realistic and interactive animations, Euphoria is one of the most advance ragdoll physics based engine used in most of the games today like Star wars and Grand theft auto.
Physics engine can bring realism in several aspects of a game like environmental destruction and stimulus, secondary motions like body dynamics and hair dynamics are also a part of real time physics used in games.
Gamers now a days expect a real world logic involved in games, forces like gravity friction following real world physics laws improves a lot of the look and feel of a game, Games like Batman Arkham City (you can see a real cloth simulation of Batman's Cape during gameplay, Battlefield(Bullet impacts and Building distruction), Split second is again a great example where you can see Vehicles and buildings blowing off and effecting objects in the environment. Portal is a puzzle game based on newtonion phyiscs. These all games have earned a lot of fame due to the involvement of real world physics simulation.
Some Game Engines have inbuilt physics engine to simulate real time physics and some are developed as per the requirement of a game. Market is currently dominated by these 2 middle ware physics engine SDK’s Nvidia PhysX and Havok. Both have been used by several famous Game titles, Reason being their almost fast approximation of physics calculation.
Havok which is acquired by Microsoft on 2nd Oct 2015 provides several services for different physics based situations like ,Destruction, FX, cloth, and artificial intelligence.
While PhysX which earlier was known as Novodex physics engine was authorized by Ageia, later in Feb 2008 Ageia PhysX acquired by Nvidia. PhysX is one of the handful of physics engines used in the large majority of today's games.
With each passing day we are finding so much new in the field of Gaming industry, Technology is not just enriching experience of Consoles and PC Gamers but it is also hitting mobile devices. There are several famous physics based games in mobiles like Cut the Rope, Bad Piggies, World of Goo etc. But most of them using 2d physics engine. Due to limited hardware and processing power most of the games available for mobiles and tablets are not using much complicated physics. Havok has introduced its Physics engine in latest games like Modern combat for mobiles but its only available for Iphone and Ipad, soon we will be able to play such games in most of the mobile devices too.
Next big thing in Gaming is cloud, If we could use cloud servers to calculate physics for every gaming device which is connected to it, then it would be a boon for every Gamer to see the more accurate but real time physics simulation in games with ease.
Please check out the Gameplay of Crackdown 3 which is a very good example of a modern game using latest technology for physics simulation. Thank you for your time.