You have your main character walking and all, but 8 frames are just not enough for a walk cycle. What now?

In a previous post I told you all about how we made our characters walk, what's a walk cycle, etc. So in this post I'm assuming you know all about that already. Just a quick recap: we drew the frames one by one for each animation, which is a long and somewhat painful process. Not to mention we couldn't afford the time to make our animations smooth enough. We found the solution to these problems when we started using OpenToonz.

Again, this is probably nothing new to professionals in the field of animation, but it may be useful to rookies like me.

The idea behind the approach is that instead of drawing each frame, you define a skeleton for your character and define the key points of your animation on the skeleton.

How does that work?
There are different methods of achieving it, but the first step is probably chopping up the body. Yes, it does kinda sound as if you were a serial killer. :D You have a nice little design for your character. You need to split that image into body parts by the joints.

This is how we cut Johnny:

The next thing you need to do, is put the character back together again, but this time, you define a bone and joint structure (a skeleton) for him. Here's how we did it in OpenToonz.

There is a handy feature called the Plastic Tool (you can find it on the left in the toolbox in OT). This is what we used. First I just dropped all the body parts into the scene, then using the Plastic Tool I created a mesh for each body part.

Building the mesh is just clicking a button, you don't actually have to do anything. You can customise the density of the mesh though.

It may be worth noting at this point that we used insane resolution raster images for this. The full image is about 6000x6000 pixels, which we then export as a 512x512 pixel sprite.

After the mesh is created for the body parts, you can add bones. Usually you will want to add bones as they would appear in a real skeleton (much simplified, of course...). Take a look at Johnny's arm here:

One bone for the upper arm, one for the lower, connected by the elbow.

Once you have the whole skeleton ready, you can start making your animation. Now that your character's body parts are held together by the skeleton, you can start moving body parts around like those of a doll. The bones won't let you stretch them, and they will be confined to the joints that they are attached to.

Ok, first of all so far this could have been done with practically any software that features any kind of animation. It could have been done inside Unity with the build-in animation system instead of sprite sheets. Also, if you look at Johnny's arm above we've got a tiny problem: the upper and lower arm images don't quite match once I start moving the bones around.

Here's where the magic comes in... The real power of the Plastic Tool is that it warps the underlying image based on the skeleton you define. You can't see this on the image above, because the structure is really simple, it is a single bone, so basically I am just rotating the image around a fixed point. Ok, let's fix this mess... To align the contours of Johnny's upper and lower arm I added some extra bones to the lower arm and voilà:

Note that these are not "real" bones, but it helps a lot in warping the image to the right shape so I can properly join the body parts again. And similarly, there are no bones in hair or in clothing in real life either, but including them in the skeleton lets you create some really cool animations.

We gave Johnny a bit of redesign regarding his clothes but that had nothing to do with changing the animation, we just felt he looks better this way.

Now, let's compare old 8-frame Johnny to brand new, 32-frame Johnny...

I don't think I have to say anything else.