rigging character, but shrinks when I rotate it.

I have a character and im rigging him to have his arms and legs rotate, so i create a key, go into edit mode rotate his arm 90 degrees, get back out of edit mode. But when i slide his bar along his arm rotates but for some reason the arm shrinks (being it’s smallest at 0.5) then becoming larger again at 1.0
Any help or just why this is happening would be appreciated.

You do not animate in edit mode, you should be editing in pose mode!

the object that i have does not have a pose mode (it’s just a normal mesh) i create a shape key, press tab to go into edit mode and rotate my arm then press tab to get back out

Shape keys only store linear transformations, not rotations. If you look closely as you move your slider, you will see that each point on your mesh is going on a straight line from its initial position to its target position. If I am correct with my math, the object’s scale will be about 1/sqrt(2) (or about 0.7) of what it should be when the slider is at 0.5.

You may be able to approximate SMALL rotations with shape keys, but large rotations (like 90 degrees) are big enough for this shrinking to become noticeable. (If you had rotated it 180 degrees, it would have shrunk to nothing at 0.5!)

This is what armatures and bones are for. If the shrinking is unacceptable, and I presume it is, use an armature to deform your mesh.

here is a demo on how to do that,
go to layer 1 and press play :0

you want to rig for animation keys ? not physics?


Worm2.blend (601 KB)

This is what I mean by not the exact right shape (the second one is when i manually manipulate the mesh in edit mode (what i want) and the first one is what happens when i use armatures).

If there’s away i can do the second oone with armatures (or any type of deform that can use shape keys) that would be great.


you need more geometry, the elbow is not there,


ArmatureDemo.blend (384 KB)

It’s actually meant to look square, I’m trying to make a minecraft like figure.

drop the subdivide
it’s made of a square

you need 1 set of faces for the forarm, and one for the arm… if I deform the corner of one, its attached to the corner of the other

so the elbow needs it’s own set of faces.

rather then just parenting to the armature try making vertex hooks, this works for making shape keys,but not running the armature in game(like this)


Worm2.blend (601 KB)

So arm ------/------ square triangle square is the appropriate secret code for making arms apparently

here is a pic of it

on the last shape I merged the last two verts to complete the blockey arm

and here is what is what

wow, I think I just figgured out blenderCAD - just have the dimensions/text etc as an overlay, that is generated right before render :slight_smile:

Use a combo of a couple of shape keys, an armature, and a couple drivers. Rig up the arm with an armature, rotate the arm, and create a shapekey moving the verts to the shape you want. You’ll have to set the armature modifier to being active while in edit mode for the mesh to do this. Then add a driver to the shapekey and drive it with the rotation of the bone.

I did a quick & crude example. To get it really nice, would need to create 2 shapekeys, one for 45 degrees of rotation and one for 90 degrees of rotation. If you want to rotate the arm more than 90 degrees, then more shapekeys would be needed. You’ll need to create your own curves for the drivers. You’ll have to learn a few things to make it work, so just post back here if you have questions about the example…



example_shapekey.blend (424 KB)

Thanks for all the excedllent quick replies, I just a bit confused on Revolt_randy’s example.

  1. How do you set the armature to being active (i tried using google but couldnt seem to get the exact right key words)
  2. Did you just use the automatic weights that came with the armature?

If you could do a detailed step by step guide on how you did it (especialy detailed around the driver parts, i have zero experience with them), it would be greatly appreciated.
Or if you could lead me to a good drivers tutorial (even better of it’s a drivers/armature tutorial)
Or else ill just continue searching on the internet


ok always run - armature

connect to rigid body joints
set limits
have fun!

Thanks, everyone for all your time and effort
figured everything out, you’s were a MASSIVE help.