how to get the direction of motion of rolling ball

Game Engine Game Engine Support and Discussion
1

I want to make a little game, a ball is dropped onto the ground and rolling. I want to use UpArrow key to give the ball a force in the direction of motion, so when the key pressed the ball will move faster. When the ball moves, the three axes changes, I don’t know how to get the direction of motion.
Can anyone help?

2

With python you could use getLinearVelocity() and setLinearVelocity() to retrieve and set, respectively, the velocity vector of your ball in world coordinates.

3

I agree, if you just want to be able to make the ball go faster and slower, you use getLinearVelocity() to get the velocity and then you multiply that by a number and then use setLinearVelocity() to assign that back. If you multiply by a number bigger than 1.0, you will go faster, if you multiply by a number between (0, 1.0) you will go slower.