Changes

In order to advance the simulation forward, <code>update(int now)</code> should be called every frame. Naturally, PhysicsScene's <code>update()</code> should be called from within <code>Engine</code>'s run. Physics should be updated before design is updated. Let's look at how this is accomplished in the reference implementation: <pre>now = rightNow; // retrieve user input, if anykeyboard->retrieveInput();mouse->retrieveInput();joystick->retrieveInput(); // updatethe model componentsphysicsScene->update(rightNow);design->update(rightNow);scene->updateEmitters(rightNow);viewing->update(rightNow);audio->update(rightNow);lighting->update();hud->update(rightNow);</pre> This is sufficient to add physics simulation support to Chris' framework. This won't magically cause your objects to suddenly start moving around and reacting to gravity however. To do that, each object that should be simulated by the simulator must be associated with a RigidBody.