Rigging circular obiects for wheel deformation ?

Hi folks … im a starter to rigging and animations and i kinda bitten into it really hard. Working on an open project of a vehicle simulation and thought to simulate wheel-pressure dependend deformations. Thought was to rig a wheel in a star-like fashion and animate it in an external engine trough moving each of the bones to the wheel-center depending on the actual rotation state of the wheel (to define, when its facing the ground) and the pressure of the tire (for the magnitude of deformation - of course white some other variables in mind too - but that is just mathematics on the engine part). Problem is, that an armature needs to have even optically very well defined where to start and stop for the automatic weight-painting option and that’s why it cant calculate it for the wheel when i try to parent it.
Layout looks like this :


I tried to parent them whiteout automatic weight-paint calculation and defined vertex-groups manually under the same names as the bones - but cant find a way to link them together, so that they stick to the bones. Now im not sure if im aether doing it wrong, or it is not possible to rig an tire this way at all for such animation. Also, the tire mesh cant be split as blending between tiles would be greatly complicated.

Had any of you tried to do something similar or have an idea how to do this ?

You probably need an armature modifier on the mesh object, the wheel. It looks like you don’t have one, according to the bottom screen shot.

Randy

I select the armature in the object column of the modyfier but applying doesnt seem to take any effect at all …

You don’t need to apply the modifier, just add it to the mesh object, set the name of the armature object, and ensure that vertex groups is enabled. Now if you pose a bone, the mesh object should change shape. Applying the modifier will permanently change the mesh object and remove the modifier, this isn’t what you want. You need to have the modifier added to the mesh object, and it be active all the time, for it to work.

If you have problems, please upload the file some place, and I’ll take a look at it.

Randy

Ah …so some modifiers need to be just highlighted ? Tried it and it works - it seems it chose the vertex group not due to the matching names white the armature, but the order i created them, but it isnt much of a problem there to re-make it white this in mind. - also, didnt think it will be so much reactive to the weight-paint, will probably need to re-make them paints too (guess that tool needs some practice). Thanks for the help Randy ! I probably will need help at export too … but i let ya know when that time comes.

Not highlighted, (not really sure what you mean by that) but they need to be on the object. When the object is selected, all modifiers for that object will be seen in the modifier’s properties panel, and generally that’s how they are left. In some cases, yes, you would want to apply them, like the mirror modifier. But the armature modifier just needs to be added to the object, set the settings as needed, and leave it be. As long as it’s on the object, the armature will control the object, remove the modifier and the mesh will not longer be modified by the armature. If you apply the armature modifier, it will change your mesh to appear how it does with the bones posed. The mesh is permanently changed and cannot be controlled by the armature any more.

  • it seems it chose the vertex group not due to the matching names white the armature, but the order i created them, but it isnt much of a problem there to re-make it white this in mind. - also, didnt think it will be so much reactive to the weight-paint, will probably need to re-make them paints too (guess that tool needs some practice).

It works in that a bone’s name controls the vertices in the vertex group with the same name. Shouldn’t be the order you created them. Anyhow, to effectively weight paint, delete all your vertex groups from the mesh object. The armature modifier needs to be set to use vertex groups, and disable bone envelopes. Select the armature in pose mode, shift select the mesh object, now from the mode box in the 3d view, change to weight painting mode. Now you should be able to select a bone, and start applying weight for the bone, it will create the vertex group for you. You can move the bone, by selecting it and pose it as you want, and you’ll see how the mesh changes. For you’re wheel, you’ll need to weight 3 consecutive radial bones, then try posing the middle bone, you’ll see how the mesh is deformed and can adjust weighting as desired. I say do 3 bones, because weighting a vertex to 1 bone at 25% and not weighting it to any other bone, it will behave like it weighted 100% to that single bone. It needs to blend into other bone’s weights. And a quick tip: turn on auto normalize in the weight paint’s left menu in the 3d view.

Thanks for the help Randy ! I probably will need help at export too … but i let ya know when that time comes.

Dunno much outside of blender, sorry,

Your welcome,
Randy