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I have created a model and added armature to it. I want to bend the center mesh in ^ shape. I tried to solve this with weight painting but it didn't work as expected. Is there a way to bend the model, so it looks like a walking caterpillar?

Any suggestions or help? Thanks.

model and armature

bending with weight painting

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    $\begingroup$ Please show the attempted bend in a still image to improve clarity. The bend is currently shown very briefly. The current situation makes it difficult to see for comparison purposes. $\endgroup$ Mar 25, 2019 at 15:45
  • $\begingroup$ @atomicbezierslinger i can pull up the bones so that it can bend. Any suggestion. $\endgroup$
    – atek
    Mar 25, 2019 at 15:46
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    $\begingroup$ Please show the vertex density in edit mode. Please give a internet link to a video that show the caterpillar movement you want. Are you trying for playful bone animation or high realism bone animation? $\endgroup$ Mar 25, 2019 at 16:55
  • $\begingroup$ Is this a toy in two parts that hinges in the middle? $\endgroup$
    – batFINGER
    Mar 26, 2019 at 9:13

2 Answers 2

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I'm not sure it will fit your need because it looks like your object is stiff and my solution is rather for a flexible caterpillar/tentacle kind of object. Anyway here is a solution with the Spline IK constraint. Contrary to other methods, you can easily stretch and twist your object in all the directions. Nota Bene: You should use several layers to make it easier to prepare:

  • Create a 5 bone armature (2 short, 2 long, one short), the first one will be the root, make the 4 other bones as long as the mesh.

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  • Disable the Deform option of the root bone, it won't have any weight on the mesh.

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  • Create a curve as long as the 4 front bones, subdivide it and make the vertices overlay the bones head.

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  • Give the front bone a Spline IK constraint, choose the curve as Target, give it a Chain Length of 4.

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  • As you can see, your curve vertices now control the bones head.

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  • Switch your armature to Pose mode, select the root bone, then select the curve, shift select the bone, and parent with a ctrlP > Bone.

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  • Now to make the control much easier and to be able to come back to a basic rest pose, you're going to create a second armature that will control the curve vertices: First create a bone for each head.

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  • Switch this new armature to Pose mode, select a bone, now shift select the curve, go in Edit mode, select the corresponding vertices, and press ctrlH > Hook To Selected Object Bone. Same for all the other bones.

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  • Now as you can see, the new armature control the curve vertices.

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  • Switch the first armature to Pose mode, select the root bone, then select the second armature, select again the root bone and ctrlP > Bone. Now when you'll move the first armature it will move the whole thing.

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  • Change the display of the first armature from Octohedral to B-Bone, Segment the 4 front bones (2 or 3 segments) to have a more flexible armature. Don't do it if you want to keep a stiff object.

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  • Parent the mesh to the first armature with a ctrlP > With Automatic Weight.

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  • Make sure that the Armature modifier is above the Subsurf. Enable the Preserve Volume option.

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  • It should work.

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    $\begingroup$ Nice answer. Would emphasize the automatic weights, perhaps with an image showing result. $\endgroup$
    – batFINGER
    Mar 26, 2019 at 8:59
  • $\begingroup$ you mean an image of the mesh in weight paint mode? $\endgroup$
    – moonboots
    Mar 26, 2019 at 9:01
  • $\begingroup$ Yep. the weight painting in the OP is poor, hence the result. It also appears the `piller in q is maybe a toy that hinges in middle. $\endgroup$
    – batFINGER
    Mar 26, 2019 at 9:10
  • $\begingroup$ oh you're right, I missed it was a solid stiff object :/ $\endgroup$
    – moonboots
    Mar 26, 2019 at 9:16
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    $\begingroup$ No, you did get it, and you're right. $\endgroup$
    – Robin Betts
    Mar 26, 2019 at 13:40
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Suggestion

  • For playful low realism consider a lattice modifier. You may also you can consider a wave modifier.
  • Less Likely. Consider shape keys to create a depression to anticipate the bend. Skinny limbs show less issues. Plump limbs show more issues. This is only in regard to extreme spine positions.
  • Archive your current file.
  • Create a new armature with many more bones to have more flexibility. Make sure your vertex density is high enough for you artistic purposes.
  • Consider the back and front of the caterpillar as similar to the left and right human arms. (or Butterly Wings ) The human arms situation requires <<2>> sequences of bones plus a parent bone in the middle. Your situation will probably require that as well.

  • The caterpillar movement is subtle in my sample video. You may need to consider an armature with envelope weight.

  • Search on BSE for caterpillar or similar ... I think there exist discussions on similar topics.
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  • $\begingroup$ can you plz shave with a basic shape and make it bend and let walk like caterpillar. Thanks $\endgroup$
    – atek
    Mar 25, 2019 at 15:52
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    $\begingroup$ Oh no ... a negative vote ! 🏄🏽‍♂️🌊 $\endgroup$ Mar 25, 2019 at 16:55
  • $\begingroup$ @atek I did not understand completely what you wrote in the comment. I have not seen any improvements to your question. I may or may not see improvements to question. I am not providing a tutorial. We do not seem to understand each other. We may be on different time schedules. Good Luck. $\endgroup$ Mar 25, 2019 at 17:06

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