12 November 2010

Robot Dog (WIP) #4

More model tweaks! yaaaay!!....
And the spine!!!....... urgh....

This time it was more to bring it back towards the original sketch. namely around the shoulders and head.

For the shoulders I covered up the open shoulder joint exposing the ball with a panel and some grating. I then added some more detail to the top pipes. Making one an exhaust of sorts.

The clavicle piece itself I tweaked after realising in an animation test that the shoulder disk intersects with it too easily (this is why you should always try to "break your rigs").

Next up I morphed his head a little, mainly making the snout shorter and sharper, thinning the top of his head and rotating his eye sockets so they're more forward facing.

Oh yeah, and I modelled and rigged the spine....

This was a little too fun.
I kept the original curve that was hooked up to the rig and scrapped the curve modified array. Instead I made a new armature (needed to stop looping issues) and created a spline IK chain.

Then the fun bit....

For each bone in the chain there are 5 pieces of model;

main ring
ball joint socket
ball joint

All of these pieces were then link duped and not parented, but constrained to each bone. The bar was just copy transform'ed, as it needed the scale of the bone to cope with the minimal stretching across each bone segment (XY scaling is disabled on the spline IK so it wouldnt inflate the bar). The rest was then copy rotation'ed and copy location'ed. The trick was each piece had a different head/tail value on its copy location. The main ring and bridge had 0.5, keeping them in the centre, and the ball joints were at 0 and 1, placing them at each end.
So that rigged up the pieces, but spline IK isn't that great at twisting....
So then each bone in the spline spine (thats fun to say... teehehe) was given two copy rotations. One locally copying the Y axis of the body bone and the other locally copying the Y axis of the butt.
Here's the trick, each bone had their modifier's influence balanced between the two according to how far along the chain it was. ie, the one closest to the body had 0.9 on the body rot, and 0.1 on the butt. Next one along at 0.8 / 0.2 and so on down to the middle at 0.5 / 0.5 and on to the butt end at 0.1 / 0.9 reversed.

So thats the solid parts done. Now the soft gooey pipes.
On the pic above you can see other little bones on each side of each segment. Each one parented to the segment its beside. The splines for the pipes running along side the spine have an auto handle for each segment, which were then hooked to the little bone on the side. With the ends hooked up to the rest of the body. Pipe geometry then done as before, array/curve moded.

The neck was rigged up the same way, pipes and all. Except that I decided to scrap the large rings after again seeing in the test animation I couldn't rotate it far enough without intersections. The the inner pieces I tweaked a little to give it more bulk. It still looks a little flimsy in context with the rest of the model, but after all the tedious fiddly crap with the rest of the spine, I decided to put it on my "f**k it for now, ill do it later" list

With that all done I did another animation test, but I wanna tweak it a little more before showing it. Plus I figured I gave you enough to read in this one to last you another day or so.
Till the next fist,


  1. Love the Dog - and watching the process of you rigging it. Thats always been a part of blender that I've wanted to delve into but has foiled me at every attempt.

  2. Thanks for the praise!
    Some time next year ill be bringing out a Rigging Training DVD, so keep an eye out for that one :)

  3. I can see a lot of people interested in a Rigging DVD especially with this model (and spine approach!).


  4. Hello! We are having our thesis ispired by DVD design. I just want to ask what type of cable did you used with your design? Thanks in advanced