yake::physics supports any number of physics plugins. The following snippet of code (based on typical Yake demos) loads two physics plugins:

loadPlugin("physicsODE");
loadPlugin("physicsNX");

Now we need to create the physics systems so that we can create the simulations:

IPhysicsSystem* pPhysicsSystemOde = create<IPhysicsSystem>("ode"); // ODE based
IPhysicsSystem* pPhysicsSystemNx = create<IPhysicsSystem>("nx"); // Novodex based

Now we're ready to create worlds!

A physics::IWorld object encapsulates a simulation. It's also a factory for a variety of objects (actors, shapes, joints, motors, affectors …).

Let's create a world:

SharedPtr<IWorld> pWorld = pPhysicsSystem->createWorld();

You can create any number of worlds (aka simulations).

Typically you want to set the global gravity for your world.

pWorld->setGlobalGravity( Vector3(0,-9.81,0) );

NB: For this tutorial we assume Y is the up vector in the world. NB: It is possible to add local gravity zones using affectors.

Different physics systems ship with different solvers. Different solvers often have different settings. Let's enumerate the solvers, choose one, and set a property for it (the step size).

// get all possible solvers
StringVector solvers = pWorld->getSupportedSolvers();
assert( !solvers.empty() );
 
// select the first one in the list
pWorld->useSolver( solvers.front() );
 
// get all possible properties for the current solver
PropertyNameList params = pWorld->getCurrentSolverParams();
 
// set stepping to 50 Hz
if (contains(params,"stepsize"))
	pWorld->setCurrentSolverParam("stepsize", "0.02");

First, the code:

pWorld->step( 0.1 ); // pass elapsed time in seconds

Generally, world implementations are free to decide to run the simulation in one step, or a hundred. You don't know. But we set the solver's “stepsize” to 0.02 seconds so we can safely assume that the world will internally be stepped 5 times.

Now you're ready to fill the world with objects.