Andengine Traffic game: moving sprites along path on map

Question

I'm developing simple traffic educational game like https://market.android.com/details?id=cz.allianz.krizovatky.android . When the player taps on car sprite, it started to move with other cars. If player made a mistake in choosing car, collision happens.

I decided to use Andengine for this game, because I have time limitation in developing it. So, the main problems is: How to make car automatically move along specified path with smooth turns? (and how to specify this path on map)

Answer 1

If you already know the path then to make it move smoothly you would apply a low-pass filter to the actual movement. A simple low-pass filter that might work for you is the weighted moving average.

For example, instead of snapping the car directly to the path like this:

car.x = pathNode.x
car.y = pathNode.y

You would only move the car partway to where the next node is:

car.x = car.x + (pathNode.x - car.x) * 0.8
car.y = car.y + (pathNode.y - car.y) * 0.8

This gives up some accuracy to smooth out sharp turns over time. You will have to play around with the weight (0.8 in this case) until it looks good.