Rigging countryballs with bones in Moho

How bones work in Moho

Bones live in a bone layer. Any vector, image or group layer you put inside that bone layer can be controlled by its bones. Moho connects artwork to bones in three ways, and choosing the right one is most of the rigging work:

• Flexible binding (the default): points are pulled by nearby bones depending on each bone's strength. Good for soft shapes that bend.
• Layer binding: a whole layer follows one bone rigidly. Ideal for countryball eyes, hats and held objects, which shouldn't bend.
• Point binding: you pick specific points and bind them to a bone. Useful for precise control, such as a stretchy part of a body.

Step by step: a countryball rig

1. 1

   Step 1: Organise the layers

   Create a new bone layer and name it after the country. Inside it, put a group containing the body (the mask), the flag and the outline, as in how to draw a countryball. Above that group, add a switch layer called "eyes" and, if needed, a layer for a hat or prop.

   A switch layer shows only one of its sub-layers at a time. Put one eye drawing per expression inside it (neutral, happy, angry, sad) and you can change expression in a single frame.

2. 2

   Step 2: Add the root bone

   Select the bone layer, go to frame 0 and choose the Add Bone tool. Drag a short bone upward from the bottom-centre of the ball to roughly its middle. This root bone is the handle for the whole character: moving, rotating or tilting it moves everything.

3. 3

   Step 3: Add child bones

   With the root bone selected, add a second bone from the centre towards the eyes. Because the root was selected, the new bone becomes its child and follows it. Add another child bone where the ball will hold an object, such as a sword or a flag on a pole.

   Name every bone in the bone panel (root, eyes, prop). Clear names make animating, and later fixing, much easier.

4. 4

   Step 4: Bind the layers

   Select the eyes switch layer, pick the Bind Layer tool and click the eyes bone. Do the same for the prop layer and its bone. Bind the body group to the root bone the same way, so the ball stays a perfect, consistent shape when it moves.

   Want a squishier ball later? You can instead let the body's points follow bones flexibly or bind specific points, but start rigid. It's easier to add softness to a working rig than to fix a melting one.

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   Step 5: Test the rig

   Go to frame 1 and grab the bones with the Manipulate Bones tool. Rotate the root: does everything turn together? Move the eyes bone: do the eyes slide without leaving the body? Switch expressions: does each one sit in the right place? Fix problems on frame 0, then test again.

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   Step 6: Animate with it

   Now animate as described in how to animate countryballs: keyframe the root bone for hops and tilts, the eyes bone for glances and the switch layer for expressions. Moho adds keyframes to the timeline automatically when you move a bone on any frame after 0. Right-click a keyframe to change its interpolation, for example to ease in and out.

   For squash and stretch, scale the bone layer or group with the transform tools on the frames before and after a jump.

Reuse the rig for every country

Once the rig works, save the file as your template. For a new country, duplicate the bone layer and replace the flag layer inside the group. The bones, binding, eyes and expressions all carry over, so a cast of twenty countries takes minutes instead of days. Moho Pro also has advanced rigging features, such as Smart Bones that drive whole poses from one bone. Check Lost Marble's edition comparison to see what your edition includes.

Practice exercise