Simple question, just looking to be pointed in the right direction as I am somewhat new to things.

I'm creating an animation where a ball shaped robot (think BB8) has to roll around various terrains and scenes, in control.

I can model, texture, and keyframe just fine (though I am only just learning these things), but the best approach for the rolling ball is snagging my progress some. We will see the character close, so the contact with the ground and the rolling should be accurate as expected.

Simply keyframing the position and rotation seems impossible for this.

I know I can "draw" paths to follow, though this may not be practical in following the ground nicely, and there's the issue of making the ball roll.

I could use physics to keep the ball grounded and have it roll, though there's the question of actually making it move where I want for the animation itself.

The terrain will be uneven and realistic, like a beach or rocks or forest.

Physics may be the best solution though I've looked and can't find a way to animate a physics object, specifically a sphere, moving around to specific areas. But maybe another approach is what I need! I could be missing something about paths.

Another detail is that the rolling part of the robot doesn't need to face any particular way, it just needs to roll.

Hopefully this leans more planning and effort in the setup and less in the actual animating, as there is obviously a lot more to think about than just getting a character moving to the place you want and rotating correctly.

Thanks for any help!


2 Answers 2


Perhaps a good solution would be to use Rigid Body on the ball to allow it to roll freely and “push” it where you want it to go with a set of one or more keyframed Passive Rigid Body colliders that are hidden from rendering. This way you can push it (eg, uphill) without having to break the physics.


I would manage all your keyframes as you have been doing, set the ball to be a Rigid Object with Dynamic property, and the terrain to be a Rigid modifier, too - but the collision type set to mesh, and then bake it. Once you've done that, you could then convert the bake to keyframes, and tweak it to your liking.

  • $\begingroup$ That'd get the ball to roll just fine, though I know that already. Thing is I can't imagine it'd make it any easier to actually get the ball going to the specific places I need for the animation. The ball is supposed to be autonomous. The baked keyframes from a physics sim would be impossible to edit effectively, I feel. $\endgroup$ Dec 7, 2020 at 22:34
  • $\begingroup$ Make a hidden, simplified version of the ground that has a grove where you want the ball to go... $\endgroup$
    – Ron Jensen
    Sep 20, 2021 at 3:24

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