Adding an enemy

Before we add an enemy to the scene, let's clean up our code a little bit and create a new function called addRigidBodies in main.cpp so that all the rigid bodies will be created in a single function. To do so, follow these steps:

1. In the source of the main.cpp file, create a new function called addRigidBodies above the main() function.

2. Add the following code to the addRigidBodies function. This will add the sphere and ground. We are doing this instead of putting all the game code in the main() function:

   // Sphere Rigid Body 
 
   btCollisionShape* sphereShape = new btSphereShape(1); 
   btDefaultMotionState* sphereMotionState = new 
     btDefaultMotionState(btTransform(btQuaternion(0, 0, 0, 1), 
     btVector3(0, 0.5, 0))); 
 
   btScalar mass = 13.0f; 
   btVector3 sphereInertia(0, 0, 0); 
   sphereShape->calculateLocalInertia(mass, sphereInertia...