libgdx sphere rotation after movement

Question

I'm moving my sphere on the screen using this method:

Matrix4 m = myBall.body.getCenterOfMassTransform();
Vector3 translation = new Vector3();
m.getTranslation(translation);

float multiplier = delta * 4 * game.platform.accelerometerFactor();
movement = new Vector3(Gdx.input.getAccelerometerY() * multiplier, 0, Gdx.input.getAccelerometerX() * multiplier);

translation.add(movement);
m.setTranslation(translation);
myBall.body.setCenterOfMassTransform(m);

Then I would like to rotate my sphere during movement. So I counted angle which sphere should be rotated and then applied it before I call myBall.body.setCenterOfMassTransform(m) using:

float x = movement.x;
float z = movement.z;
Vector3 axis = new Vector3(z, 0, -x);
m.rotate(axis, angle);

But the sphere is rotating strangely. Where is the problem in my process of rotation?

Answer 1

It seems to me that the axis of rotation should be a positive multiple of

a = v x (-e_z) = (vx, vy, vz) x (0, 0, -1) = (-vy, vx, 0)

where v is the velocity vector, e_z the unit vector in z direction and x the vector product.