Code question for CARDYNAMICS::ApplyWheelForces

[NaN]

Not the most readable piece:

Code:

btScalar dw = 0 - wheel[i].GetAngularVelocity();
btScalar lockup_torque = wheel[i].GetInertia() * dw / dt; // torque to lock a free rotating wheel
btScalar wheel_brake_torque  = lockup_torque - wheel_drive_torque + tire_friction_torque;