well my question is simple:
1-why do i have to use physics engine while irrlicht has one (simple one)
2-and what is the easiest and simplest physics engine now (free)?
3- i think it is easiest making my own physics needed for the game or to use a physics engine and write millions of code!!
1. To my knowledge irrlicht has no physic engine. You don't necessarly need one to programme games (or other applications). You only need a physics engine if you need physic in your game (doh).
2. Don't know. ODE or Newton probably. It depends a lot on _what_ you want to do with it.
3. Again it depends on what you want to do. Most physic engines do offer for example just a certain physic model for rigid body dynamics. If you need exactly that, than it's likely that the easiest way is using such an engine. But maybe you need just a simple physic, but you want to be very flexible when implementing it. In this case doing the physic yourself might be a good idea. Or maybe you don't care that much for speed but a lot for very realistic physics - in this case ODE and Newton will also not be that great.
Irrlicht does have an implementation of physics, but is far from being a physics engine or library. I think its only purpose is for the demos, where crude collision detection and the such is necessary.
Regarding physics libraries to choose, I would say use the Irrlicht IPhysics Wrapper for Newton. It comes with some invaluable tutorials, as well as some great demos. You can find a thread about IPhysics in the Showcase Forums.
