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I want to set up an animation of a rolling cube for a video game. The cube needs to roll/tumble to all its sides.

When I add bones to the cube, only the parent bone seems to make the whole cube rotate (obviously) but when I rotate the next 'child' bone, the parent bones stays put...

How can I connect all the bones with each other (like my skeleton is one stiff bunch of bones) in order to make the whole cube rotate when I rotate a child bone?

ngerbens
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  • The object's origin needs to trace a specific, periodic curve as it is translated. See: https://en.m.wikipedia.org/wiki/Cyclogon – hatinacat2000 Jun 16 '19 at 19:32
  • "A point z attached rigidly to the n-gon traces out an arch consisting of n circular arcs before repeating the pattern periodically. This curve is called a trochogon" There are YouTube videos on this also – hatinacat2000 Jun 16 '19 at 19:34
  • Related https://blender.stackexchange.com/q/69731/30849 https://blender.stackexchange.com/q/119677/30849 – Leander Jun 16 '19 at 20:21
  • https://blender.stackexchange.com/questions/58225/animating-a-rolling-square-wheel-effect/58292#58292 – Duarte Farrajota Ramos Jun 17 '19 at 00:29
  • Thanks you so much for all the useful and varied stuff. The cyclogon/trochogon and the rigged cylinder article is very helpful. Great. – ngerbens Jun 17 '19 at 06:44
  • @Leander the rigged cylinder (and cube) only rotates one time and the bones stay behind after the rotation. I want my object to roll/move for a while... Do you have any ideas? – ngerbens Jun 18 '19 at 18:01
  • Your system is not holonomic. It will be impossible to create a perfect rig for this. If I was in your position I would script it using small discreet steps and/or bullet physics. But you can make it holonomic by locking two axes and only letting the cube tumble on X rotation for example. Then you would recreate the driver answer with bone constraints. If that is what you want I can add an answer. If you want the all axis possible (impossible afaik) then I wouldn't know how. – Leander Jun 19 '19 at 09:02
  • Perhaps you can post an example link, where someone has done something similiar. – Leander Jun 19 '19 at 09:02

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This is just what you need! This is a Wolfram Alpha widget that showe you the cylogons (roulletes on n-gons about a straight line). The square is a default option:

http://demonstrations.wolfram.com/TracingACyclogonRouletteOfAPolygonRollingAlongALine/

EDIT: I made a canned animation of this rolling motion here, maybe you can use it:

http://pasteall.org/blend/index.php?id=51926

hatinacat2000
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  • Wow. The cylogon is completely new to me so i will dive in and have a look. But it looks very promising! Thank you for adding an example too. The irony is that actually I need to make a box rolling that isn't completely square. But this still puts me on the right track. Thank you very very much for you help. – ngerbens Jun 17 '19 at 06:55
  • NP, one of those links in the other commenters has a link to a really phenomenal instructional for rigging the cube using drivers though, just adjust the angles and offsets a little if your shape has a different profile – hatinacat2000 Jun 17 '19 at 11:31
  • It's the one with the cylinder right? I'm definitely going to check that one out.

    The cylogon is also a complete new interesting world to me. It might even be better to use something like that directly in a game engine script. Rigged bones are probably better to export out of Blender into the game engine. Thanks again.

     – ngerbens Jun 17 '19 at 22:06