Realistic driving experience

[NaN]

Thank you for your pointers.

When driving on a normal closed circuit, is the ground contact always calculated using the mesh of the terrain directly? Or is this only used as fallback when leaving the race track?

I did a checkout of your sim branch. Unfortunately I wasn't able to compile it, receiving the following error:

Code:

src/game.cpp: In constructor ‘GAME::GAME(std::ostream&, std::ostream&)’:
src/game.cpp:126:70: error: invalid conversion from ‘bool (*)(btManifoldPoint&, const btCollisionObject*, int, int, const btCollisionObject*, int, int)’ to ‘ContactAddedCallback {aka bool (*)(btManifoldPoint&, const btCollisionObjectWrapper*, int, int, const btCollisionObjectWrapper*, int, int)}’ [-fpermissive]
  dynamics.setContactAddedCallback(&sim::Vehicle::WheelContactCallback);
                                                                      ^
In file included from src/game.h:36:0,
                 from src/game.cpp:20:
src/physics/world.h:65:7: note: initializing argument 1 of ‘void sim::World::setContactAddedCallback(ContactAddedCallback)’
  void setContactAddedCallback(ContactAddedCallback cb);
       ^
In file included from /usr/include/bullet/LinearMath/btVector3.h:21:0,
                 from /usr/include/bullet/LinearMath/btMatrix3x3.h:19,
                 from /usr/include/bullet/LinearMath/btTransform.h:21,
                 from /usr/include/bullet/LinearMath/btMotionState.h:19,
                 from src/physics/motionstate.h:23,
                 from src/track.h:27,
                 from src/game.h:29,
                 from src/game.cpp:20:
/usr/include/bullet/LinearMath/btScalar.h: At global scope:
/usr/include/bullet/LinearMath/btScalar.h:337:14: warning: ‘btInfinityMask’ defined but not used [-Wunused-variable]
  static  int btInfinityMask = 0x7F800000;
              ^
scons: *** [build/game.o] Error 1
scons: building terminated because of errors.

Compiling the latest version from the master branch was successful. One thing I noticed however is that the cars react very nervous (I'm using mouse steering). It is almost impossible to drive in a straight line, even at low speeds.
Another thing which I could observe was a very weird collision behaviour with corner curbs. Sometimes after hitting a corner curb the car was flung over almost the entire map.

Yeah, the sim branch might need some work. It also depends on sim data, won't run with current data master. Would be cool to get it functional again.

Against which bullet version are you linking? The recent ones 2.82? can cause some serious issues, due to bullet internal changes. There is a bug on the issue tracker, needs to be investigated more thoroughly.

The road patches ray test overrides the track mesh test. This can cause issues, but works quite well most of the time.