Track following train type of thingy?O.o

can someone somehow teach me or set me on the right track on how to build a rollercoaster that follows a track with turns ups and downs and what knot?O.o.....

Instead of having it rely on the Havok support in SL (= rings around a solid track), I suggest using MoveToTarget and RotLookAt, with a list of each position/rotation to get through.

you will kill havok if you try to rely on it to do the positioning of your rollercoaster. Do what Jesrad recommends.

Either that, or have your coaster car use a sensor to detect invisible prims that mark the path it's supposed to take.
==Chris

Yep

so anyone wanan teach me how to do that? make sensor that follows the invisble prim marker for the track?

I'm a bit prejudiced against the use of a fast sensor() for gathering what is, essentially, fixed data. I think you should only use sensor() to get unpredictable data.

Instead I recommend building your track out of numbered prims (name them 0, 1, 2, 3, etc...), then, when you are satisfied with the track, use a "map-making" scripted tool once to get the complete, ready-to-use list of positions and rotations for your "cart" or "train" to wade through.

You may want to look here to know how to make this, you will probably want to use a sequence of Sensor() looking for prim named "0", then prim "1", etc..., which would use llDetectedPos() and llDetectedRot() to say the position and rotation of the track's prim found. Then you can copy paste from this list into your train script.

If you modify the track you can reuse the mapmaking tool to refresh the track's position/rotation list.

If you still want to go the Sensor way, you'll need a way to distinguish between each track prims. One such way is to refer to the second prim found instead of the first, since SL will return closest objects first. And have the sensor only look forward (arc = PI_BY_TWO) to avoid confusing next track prim with last track prim.