Hi Anthony
Updating the mesh impostor everyframe will be slow. Some internal structures have to be updated and depending on your mesh complexity, it will take time.
If it’s a couple hundred triangles, it might run in realtime. If it’s thousands, it won’t fit.
Maybe with web workers but I’m not sure you’ll have total controls on impostor update. I mean, it doesn’t guarante that it will run at your frame rate.
If you have only sphere, I’d try to compute the physics. Especialy if you can compute the height from the XZ position.
To do that, start with the basics: your sphere is composed of a position and velocity. each frame, position += velocity * deltaTime. and velocity += forces * deltaTime.
Then compute the forces based on gravity and terrain inclinaison.
That’s Euler integration and that’s really useful when you code games.
Once you have the position, the sphere rotation is computed by the distance (current positon minus previous frame position). Basically, the more the ball rolls, the more rotation you have.