THE ORB: RIGGING AND CFX TIPS AND TRICKS

If, as on my creature, the eyes of your character are not oriented toward a single axis, it can be more difficult to precisely position the target/Look At joints in their axes manually.

Duplicate the points you created at the centers of the eyes to create the Look At joints. Isolate the extremity points of the eyeballs meshes, create a vector between these two points and use it to displace the duplicated points along each eye's axis. You can add an offset to push these points further.

For the weight painting and the blendshapes creation, because sometimes I split the geometry and then re-merge it, the point count could change. It creates issues when blending geometries with different point counts.

To ensure the point count is restored after merging the geometry, you can create an id attribute based on the ptnum before splitting the geometry. And after re-merging it, use a Sort node to sort the points by the id attribute.

I recommend creating an HDA containing all the rig constraints (FK, IK, Look At…) as well as other elements like blendshapes or Secondary Motion nodes.

You can duplicate this HDA and stack your animation : use the first one for base animation, then another one for secondary motion. You can also use Rig Pose nodes to add more control and manipulate joints in ways your rig HDA doesn't allow. You could even create multiple HDAs with different types of control on the same skeleton, for example, one for FK on the arms, and another one for IK.

You might not notice it, but they slightly move the entire mesh, and Shot Sculpt stores this sculpting data on a lot of points. It increases the file size and fills the mesh with color visualisation, making it harder to see where you sculpted. To avoid this, you can create a mask with Shot Sculpt on the area you want to affect, and then use any brush to sculpt it.

Armature can become slow when you adjust parameters to increase the quality and precision of the result. I recommend following these steps:

• Check the bones animation with a Bone Deform to see if there are big interpenetrations occurring between them during the animation. Small interpenetrations are not always a problem, but big ones can create a not very fancy result. If so, reshape the bones.

• Try Armature on one frame of your animation and play with the parameters of Armature Deform to find the desired look.

• Decrease the Element Size of the tetrahedons in Armature Capture to achieve a more precise and realistic result. Enable Self Collisions in Armature Deform if necessary. You can start with a lower Collision Stiffness, like 1000, and increase it later if needed. Also, try to increase the number of steps in Armature Deform to see if it improves the result. Note that all of these parameters will make Armature run more slowly.

• Once everything works on this frame, identify the parts of the animation where it could be more challenging to have a precise result with Armature Deform. For example, when the mouth or the eyes close, check if they close correctly. The influence of bones or gravity could make them not follow exactly what you want. Adjust parameters and play with skin and bones constraints if necessary.

• When it works properly on these frames, run Armature Deform on the entire animation.

When you do a Vellum or Otis simulation (for muscles and tissue), you usually remove some parts of the skin to create the tissue for the simulation, such as the head, hands and feet, and other rigid elements. You don't particularly want any physical deformation on them, but something more precise, so you animate these parts in a more traditional way and blend them with the simulated parts.

Check the intersections between muscles, bones and skin after solidifying muscles with the same tool you may have used earlier (probably with Intersection Analysis nodes), during the geometry preparation. It can be very slow to use an Intersection Analysis directly on tetrahedralized muscles, so you can instead use the second output of the Muscle Solidify to analyze intersections on the surface only.

If you notice intersections, there are several things you can do:

• First, you can use a Remesh before Muscle Solidify to get a better topology that follows the shape of your original muscles. It can help remove intersections, especially if they were caused by the remeshed surface being too low res in the Muscle Solidify node. Then, toggle off Remesh Surfaces in the Muscle Solidify.

• You can add a Muscle Deintersect node before Muscle Solidify, with the bones as a second input. And adjust the parameters.

• Subdividing the muscles before Muscle Solidify can also help remove intersections if necessary.

• Another trick that sometimes gave me good results was adding a Muscle Deintersect node after Muscle Solidify instead of before. However, this is not recommended because you shouldn't deform a tetrahedral geometry to not risk creating inverted tetrahedra that will break the simulation. If you still decide to try this approach, make sure to check for inverted tetrahedra with a FEM Validate.

If you need to customize an attribute like the tensionmask, instead of using a Muscle Paint node, you can try to create a more procedural way to do it, so if the geometry changes (even slightly), you won't have to re-cache the strokes of the Muscle Paint.

I've also created a tool where I draw a curve on the muscles. This curve has the attribute I wanted to customize, and it transfers it to the muscles, to add or replace it. You can think about other similar tools depending on the muscle's shape and the attribute's shape you wanted to paint.