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I'm a beginner, trying to rig tentacles on my creature.

I have added an inverse kinematic constraint to the end of the tentacle and for some reason when I move it looks very rigid instead of smooth. I have tried to subdivide the tentacle thinking the problem is in the mesh and have also checked the weight paint for each bone.

enter image description here

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    $\begingroup$ If you've subdivided enough then the problem comes from a bad weight painting, maybe try to parent again. Also you probably could do it with less bones and just segment each bone to get the bend. You can share your file if you want us to take a look: pasteall.org/blend $\endgroup$
    – moonboots
    Commented Mar 7, 2022 at 13:09
  • $\begingroup$ Tooke me some time to upload but here it is: pasteall.org/blend/8aff21a5bc17467fa9ff3f132ac509c4 $\endgroup$
    – atkaizer
    Commented Mar 7, 2022 at 13:30

2 Answers 2

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Remove the Decimate modifier, it looks like it messes up your topology and therefore the interaction between the armature and the mesh. More generally, the rest of your topology is a bit too dense and not verty good, you should retopologize, then give a Subdivision Surface in order to smooth the whole shape.

Maybe you should work with less bones and segment them. But if you want to keep your current armature, you first need to create additional edge loops at the base of the tentacles, otherwise you won't be able to bend the mesh:

enter image description here

Once done, if you don't want to reparent the whole mesh, select all the tentacle bones in Edit or Pose mode, switch to Object mode, shift select the mesh, switch to Weight Paint mode, then in the header menu > Weights > Assign Automatic from Bones, this operation will recalculate the weight for the selected bones only (there may be a way to select several bones once in Weight Paint mode but I don't know the shortcut):

enter image description here

Edit: From your second file, first you need to disable the Deform option of the controller bones, otherwise they will act on the mesh:

enter image description here

To segment the bones, go into the Bone panel and increase the Segments value (like 3). You can select all your bones, type the value, and AltEnter so that it applies to all the selected bones:

enter image description here

Now you can recalculate the weights again. You may need to give some small corrections in Weight Paint mode. Then it works:

enter image description here

Also for tentacles, the Spline IK constraint is interesting, see my explanations here.

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  • $\begingroup$ I have done as you suggested: reduced the number of segments and added additional loop cuts as well as recalculated bone weights but it looks exactly the same. $\endgroup$
    – atkaizer
    Commented Mar 7, 2022 at 14:12
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    $\begingroup$ please share your file again, with the changes you've made $\endgroup$
    – moonboots
    Commented Mar 7, 2022 at 14:13
  • $\begingroup$ My apologies in advance if I am not understanding something very obvious. I also really appreciate your help. Here is the link: pasteall.org/blend/ec7d4b2fda33421a9d56cb33e7b80294 $\endgroup$
    – atkaizer
    Commented Mar 7, 2022 at 14:20
  • $\begingroup$ No problem, I've edited my answer, please try and tell if it works $\endgroup$
    – moonboots
    Commented Mar 7, 2022 at 14:30
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    $\begingroup$ It looks like it's caused by this Decimate modifier, what is it for? Disable it and test again. Also you could put a Subdivision Surface modifier under the Armature modifier. The problem is that you mesh is rather high-poly, that's probably the reason why you had to use a lot of bones. Don't you want to retopologize your mesh? $\endgroup$
    – moonboots
    Commented Mar 7, 2022 at 15:25
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The problem was with the mesh, as soon as I created a tentacle with enough geometry everything began bending as expected. enter image description here

enter image description here

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