Driving around?

Yeah I've never done it myself but how about checkpoints along the road, one on either side. That way you just find the two sets of checkpoints that encapsulate the section of road which the car is currently on, interpolate between them to find checkpoints at the cars position, and check if it's between those.

I'd load in the image of the map, and store some kind of "geometry" data for the map that just consists of a bunch of collision boxes drawn fairly close to the road (not perfect, but close enough).

This is the same way they do collisions in games with pre-rendered backgrounds (FF7, Resident Evil...), I believe.

Just to warn you...
Bounding boxes is (in my opinion) one of the easiest ways of detecting collision, but therefore it is also inaccurate for anything other than blocks.
Therefore you should learn it (I didn't thought of it as beeing diffult to master).

The obvious thing is to not require the cars to stay on the track, but make it advantageous to the player to do so.

Ensure that the drag off the track is sufficiently high, it's attractive to stay on it most of the time.

Place checkpoints around the track that the player must pass to have a lap counted .

Mark

I think a really simple, robust method would be to use conical capsules -- Where you just have a segment defined by 2 pts and a maximum distance at each point and interpolate that distance down the length of the segment to create a cone-shape capped by a sphere at each end. Then if you make a loop using a bunch of these connected segments, the interior of which is your collision geometery, it should work out pretty well and be super simple...

you just have to remember that parts of the the different capsules can overlap and different parts of the car can be in different capsules and it'd still be a valid position. This also makes it easy to avoid the really nasty case where the car drives into a narrow wedge-shaped piece of the track (obviously you can still do it... you'd just have to be a damn fool :)

Try it out on paper. Draw a connected loop of points. Draw a circle around each one, and connect the consecutive circles by their tangents... This sounds interesting, maybe I'll try to knock out a fast OBB-conical_capsule test later on.

You could encode on-track and off-track data in the bmp. Then shoot rays downwards from the car extremeties and where they intersect the terrain check that texel to see if its on-track or off-track. Not sure how exactly you'd go about implementing this since its just an idea that popped in my head but I'm just trying to offer you alternatives.

Quote:

Original post by markr The obvious thing is to not require the cars to stay on the track, but make it advantageous to the player to do so. Ensure that the drag off the track is sufficiently high, it's attractive to stay on it most of the time. Place checkpoints around the track that the player must pass to have a lap counted . Mark

You'd still need to do the same kind of collision to determine whether or not they're off the end of the track, but yes, I agree with your design philosophy. That way you could hide little things on the track far off the beaten path.