I'm using the Mecabricks model for set 76010: https://www.mecabricks.com/en/models/1pyj6xRaRqZ
I have saved a copy of my blend file here: https://1drv.ms/u/s!AmLpdtQpcrjOhacCJXSUv6qarULm3g?e=hLIELc
This model uses the part 44676 four times, twice at the rear of the underwater scooter and twice near the front. When I export the model and import into Blender I want to rotate this part in an animation. I set the transformation orientation to be 'local'. I display the element properties (keyboard shortcut 'N') and manipulate the rotation value here. I'm using Blender 2.83, Windows 10 and i tried the Lite script then the Advanced script (v2.1.6).
- The two items located at the rear rotate perfectly on their Y-axis, which is what I want to animate. The other axes don't behave correctly, although I don't need them. Rotating the Z-axis actually move it on the X-axis. Rotating on the X-axis behaves as expected.
- The two items at the front of the model do not rotate correctly either. In their case the Y-axis rotation that I want does not work correctly, it rotates the same as X-axis rotation. Y-axis rotation actually rotates on the Z-axis.
I can't say if this is a Blender problem or an import problem. I don't know how to change the pivot axis behaviour in Blender. I tried the different Euler settings (XYZ, XZY, ZYX, etc) but with no positive outcome - there is always the odd behaviour of two axes being the same .
I tried rotating the helmet on the Batman minifig but also doesn't work consistently, and fails in the critical axis.
I tried deleting the two front fins in the model and cloning the rear ones. This didn't help either.
In summary
- rotation only operates on two of the three axes - even though the property value shows as being changed the visual representation is not correct
- rotation behaves differently on copies of the same element
If there is a work around to change the way an object rotates in Blender I'd be happy with that but my Googling skills have not yet revealed an answer.
To understand your problem, you shall look into Euler angles and how they work, keeping in mind that Blender uses extrinsic rotations if I remember well.
Animating rotations is not that straight forward. You cannot really animated along a local axis. Use empties when the model is in a rest position.
Thanks for tip on animating - I've got some reading up to do on that.
Meanwhile, I was still a bit unsatisfied on why I couldn't pose the piece I wanted even for a "photo". I created two test files. I used a single element, 44676, in each. In one I added the element and did nothing to it, just saved and exported the file. In the second I used Mecabricks to rotate the element 90 degrees on the Z axis so it lies flat.
File 1 - import to Blender and the rotation in Blender works as expected - each axis can be rotated and the shape moves accordingly.
File 2 - as with my above commentary, the shape can only be rotated on 2 axes, Y and Z work as normal, but manipulating the X value rotates the shape on the Z axis.
One conclusion is that there is an error either in the exported data from Mecabricks, or in the import plugin for Blender. It could also be a Blender bug of course.
Any thoughts?
Regards,
TIm.
Thought I'd do a bit more testing, so I created files with the same piece, one with a 90 degree X rotation and one with 90 degree Y rotation
X - Works perfectly
Y - Same 2 axis problem. But then as I prepared to write this note I repeated the import to make some accurate notes, and it behaved correctly.
Now I'm really intrigued. It seems I get some inconsistent behaviour on importing. Hopefully this rules out the Mecabricks export as being the issue.
Remember that the axes you see in mecabricks are not the origin of the mesh unlike what you see in Blender. These are special points defined with a position and a rotation (quaternion) relative to the part they belong to. These points are not exported in Blender. In Blender you can only manipulate the part origin.
There isn't any bugs in Mecabricks or Blender related to the rotations. That is the heart of a 3D software and a lot of love is always put into this part of the code. Rotation is not an easy topic to understand at first.
Please post some screenshots of the tools you use in Blender and Mecabricks to set the rotations and I shall be able to help you understand.
LEGO, le logo LEGO, la minifigurine et les configurations des briques et tenons sont des marques déposées de LEGO Group of Companies. ©2024 The LEGO Group.
Mecabricks, le logo Mecabricks et tout le contenu non couvert par les droits d'auteur du groupe LEGO sont, sauf indication contraire, ©2011-2024 Mecabricks.