Real-time physics

Not too far ago, there was no 3D accelerated cards. It was the CPU the only able to make 3D graphics a reality. Now, nobody is even able to buy a PC computer without such a possibility.

But gaming industry needs go beyond, and once again, not only this industry but every field in computer science is going to take the most of this new need.

I'm talking about real-time physics.

But firstly, some background. What's real-time ?

An operation within a larger dynamic system is called a real-time operation if the combined reaction and operation time of a task is shorter than the maximum delay that is allowed, in view of circumstances outside the operation. Wikipedia definition.

In computer graphics, this is very related with interaction. Real-time means that we are able to provide an interface to the user, in which he/she can interact and get a graphical response with the same rate as the real world we are trying to simulate, i.e., no more delay we get from the real world. Simple to say, quite difficult sometimes to achieve.

Real-time used to be associated with geometry simplification and LoD techniques (Level of Detail). It still is, but recently we have to take into account one new element: physics simulation.

A physics engine is a computer program that simulates Newtonian physics models, using variables such as mass, velocity, friction and wind resistance. It can simulate and predict effects under different conditions that would approximate what happens in real life or in a fantasy world. Wikipedia definition.

Obviously, for real-time physics it is required to simplify its calculations and/or lower their accuracy in order to respond at an appropriate rate for interactivity.

The need of real-time physics is so important, that we are going to see the launch of specific processing units (the same that happened with 3D acceleration). See this ageia web site and look for PhysX.

Summary. Always an example is the best we can do to understand concepts. In the following video, we can see a water simulation. In this case, we don't speak about real-time, so it is possible to calculate this simulation without losing accuracy.

(if you have bandwidth problems, watch all the video until the end, and press 'play' again; normally the cache is going to help you the second time)



And now, something in real-time. In this case, a preview of what the new PlayStation 3 is going to offer us:



Very impressive !