So I have a torus, and I need it to "telescope" open -- kind of like Pacman's death animation, but with a torus instead of a sphere.

I'm very new to 3D modeling/animating so I really have no clue how to tackle this problem. Any advice to help me get pointed in the right direction would be most appreciated :)


1 Answer 1


You could do this easily with a torus curve, if you dont mind the bezier curve object.

Just add a Bezier Curve Circle, make its handles Free type and erase the bottom half (or whichever suits your design).

Make it 2D type with None fill so it is like a torus.

Adjust the bevel radius and resolution as desired. Add a Mirror modifier in the corresponding axis to mirror the animation.

You can now animate the aperture with the *Bevel Factor > Start and end factors.

Packan Telescope Torus

Alternatively if symmetry is not your concern, you may simply turn the circle into an open shape by duplicating one of its vertex and erasing one segment, and then controlling both the Start and End Bevel Factor values independently.

  • $\begingroup$ Thank you so much for the detailed reply, I will give this a shot :) $\endgroup$
    – Jason H
    Oct 26, 2016 at 16:35
  • $\begingroup$ so I tried out your solution and it worked perfectly. The only problem is that now I'm trying to import the animation to unity and it won't work -- I'm reading here that unity imports bevel curves as meshes, so it sounds like the bevel factor control is lost. Do you know if there's a way to achieve the same effect using rigging? I'm worried I'll have to do this programmatically in unity, but I'm trying to avoid that if at all possible. $\endgroup$
    – Jason H
    Oct 27, 2016 at 5:08
  • $\begingroup$ You could probably do it with rigging, but that is really not my area of expertise, I would not be able to help much there. Maybe post a new answer with all those details and requirements so somebody else can help. Does Unity import shapekeys? Maybe you can achieve the same effect with shapekeys too. $\endgroup$ Oct 27, 2016 at 15:24
  • 1
    $\begingroup$ I ended up biting the bullet and doing it all in code. Actually turned out to not be so bad, since I already had a script building a torus -- I used two scripts, each building a half torus, and then I just paused for some fraction of a second before building each segment for the closing animation. For the opening animation I just built all but the last segment in one frame, all but the last two segments in the second frame, etc. Feels dirty but it works. $\endgroup$
    – Jason H
    Oct 27, 2016 at 16:57

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