In Leadwerks Engine 2, physics bodies and character controllers are both separate entity classes. If you want a model to be physically interactive, you parent it to a body entity. If you want a model to walk around with physics, you parent it to a character controller body.
In Leadwerks 3 I decided to give physics properties to all entities. This means all entities can use commands like GetVelocity(), AddForce(), SetMass(), etc. However, since character controllers are quite different, and they involve kind of a big chunk of code, I decided to keep the character controller as a separate entity. To make an enemy or NPC, you would create a character controller entity and then parent an animated model to that entity.
This was simple enough to do in the editor, but it started getting weird when we added scripts. Scripts for animation would need to be added to the child model, because the character controller would not return any animation lengths or the number of sequences. Scripts to control movement, on the other hand, would have to be attached to the parent character controller, for obvious reasons.
Next I tried creating a character controller script that attached to the model itself. This eliminated the extra entity in the hierarchy, and would automatically create a character controller when loaded in the engine, and parent the model to it. I didn't like that this was changing the hierarchy from what the user saw in the editor, and script accessing the character controller would still be based on some wonky assumptions.
Finally, I decided to just give the entity class a physicsmode member. This can be one of two values. By default, it is Entity::RigidBodyPhysics. However, you can set it to Entity::CharacterPhysics and the entity itself will act as a character controller! All the character controller functions are now available in the entity class, so you can just load a model, adjust some settings, and send him on his merry way around town:
Model* enemy = Model::Load("Models/Characters/barbarian.mdl");enemy->SetMass(10);enemy->SetPhysicsMode(Entity::CharacterPhysics);enemy->GoToPoint(20,0,0);//model will walk to this position, using AI navigation
Pretty cool, eh?