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I have an FBX file that represent a plane with an animation of the gear opening. In my editor 3DSMax or in the Unity editor, the file and animation seem good, but when I use Open 3D Model(the official viewer of Assimp) or when I call the FBX file simply in an application, to see what the file will look like with the use of Assimp, I got some issues.

The object seems normal at the beginning, but when I try to launch the animation, all my animated elements are going crazy.

Here's what it looks like :

Plane

Here's my FBX FILE

Do you have experience something similar ? Does it come from my file or a parameter in Assimp ?

I am beginning to think that there is a problem with how Assimp handles pivot points, looks like objects are rotating using a different pivot point in Unity/open3mod.

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  • \$\begingroup\$ Could you include some source of how you are utilizing AssImp? \$\endgroup\$ – user5665 Jul 7 '16 at 0:42
  • \$\begingroup\$ The fact is I don't use it, I only use an application that uses it, I am beginning to think that there is a problem with how Assimp handles pivot points, looks like objects are rotating using a different pivot point in Unity/open3mod. \$\endgroup\$ – Evans Belloeil Jul 7 '16 at 14:54
  • \$\begingroup\$ Then that application is not functioning how you expect, it's not an issue with AssImp; What exactly is your goal here? What do you want to happen and what can you change about the program you're using if it isn't your program? \$\endgroup\$ – user5665 Jul 7 '16 at 15:55
  • \$\begingroup\$ My application is open3d, the official viewer of assimp. My goal is to use assimp in an application but it can't load my fbx properly, and I don't know if it comes from my file or from assimp. \$\endgroup\$ – Evans Belloeil Jul 7 '16 at 20:13
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    \$\begingroup\$ Can you provide any further information about the model, how it is defined, how it is loaded, et cetera? Otherwise this is probably unanswerable here. \$\endgroup\$ – user1430 Jul 7 '16 at 20:39
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I had the same issue when I was attempting to make a model for a UAV in Blender and import it to unreal engine. I think I recall as a solution I just redid my bone weights and it fixed the problem. Then i rotated the model to go the direction I wanted to in unreal.

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  • \$\begingroup\$ Could you look at my file posted in my edit ? I don't think I have a bone weights problem. \$\endgroup\$ – Evans Belloeil Jul 8 '16 at 13:30
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Typically you need to zero out any transforms before you export into an exchange format or else it's bound to go totally crazy on the other end.

That could be the issue.

It could also be a bug in the exporter or in how assimp reads it. File formats like FBX are very complicated and this is very common.

If you export the animation/skeleton separately it's also important that you export the exact same things (same selections) and make selections of nodes in the same way or it will also probably fail.

In short it could be many things and it is very hard to diagnose it exactly without sitting on your computer and/or looking at the file contents themselves.

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  • \$\begingroup\$ I just posted my FBX if you want to take a look. \$\endgroup\$ – Evans Belloeil Jul 8 '16 at 13:32

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