This started as a test of a character whose limbs come out from inside their body. A poster on Reddit was asking about it and while I knew it was technically possible, I didn’t feel right saying so without confirming that it was practical with the method I had in mind.
The tricky part of making the limbs come out was creating the correct vertex groups. You can’t use automatic weighting because it invariably weights the body with some of the limb influence. I assigned everything manually. I also thought that when you created a bone and then used the Symmetrize option, it would create the vertex groups for the new bone but it didn’t happen in this case.
Part of this project was to experiment with uploading rigged characters to Sketchfab. It is definitely not as straightforward as I hoped.
I originally used a shape key for the eyes but that meant I had to switch in and out of pose mode while creating the animation to get the timings right for everything. It also doesn’t seem to work when uploading to Sketchfab. I’ve used bones before and I’ve used shape keys before on Sketchfab so I know they both work. I think the combination of the two on one character is the problem. I ended up using bones for the eyes, one for the upper eyelid and one for the lower. When I tried using a single bone for both, it worked in Blender but Sketchfab couldn’t figure it out and the eyes were twitchy.
I only uploaded one robot to Sketchfab because I couldn’t find a way to preserve the timing of the actions on multiple objects. It would have been nice if it just used the NLA track to bake the animation. Maybe there is a way around that.
I rendered the video in Cycles just for the experience. I don’t think it would look any worse to have done it in Eevee and would have taken a fraction of the time. Maybe if I had more interaction between the objects and the lights Cycles would have been worth it.
The material on the robots glitches slightly as they move. I used generated coordinates feeding to a Musgrave texture. I need to look more into how texture coordinates work with moving objects.
I would like to experiment with more complex shapes. It would be cool to do a character with limbs that “grow” out from the body like vines. I will have to experiment with that to make it look right.