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Inverse Kinematics
This rig features a robust inverse kinematics system that offers several options for the animator to use. Each limb can be individually switched to use Forward Kinematics or Inverse Kinematics, and IK controls can specify their parents for more in depth animating.
Forward kinematics poses the limb from start to the end. BY default, the arms are in forward kinematics. The controls look like this on the arms and the legs (but note that the colors are different on each side):
The FK controls on the elbows and the knees (CTRL-ForearmFK and CTRL-CalfFK) have constraints on them that disallow them to rotate beyond what they reasonably could in real life.
Inverse kinematics poses the limb by specifying a position that the limb should end at, and a position that it should bend towards. By default, the legs are in inverse kinematics. The controls look like this on the arms and the legs (but note that the colors are different on each side):
You can specify the parent for every limb IK control and IK pole target (where the knee/elbow points towards)
By default, the main IK control and the IK pole target are parented to CTRL-Root. This can have some fun interactions when moving CTRL-Pelvis around:
All of the IK controls can be parented to CTRl-Pelvis:
The arm IK controls can be parented to CTRL-Chest:
It is also possible to make the IK controls have no parents at all:
There are two additional parenting options specifically for the IK pole targets. They can be parented to their corresponding IK control:
Or they can be parented to the calculated position of the middle of the limb (the knee or the elbow). This is the trickiest mode to handle, but if you are confident in your abilities you can have less overall keyframes in your animations.
There are also two settings for quickly assigning the parent type for all of the respective controls, instead of needing to manually set them all.
This rig allows you to 'snap' between the two kinematics systems; for example, you can pose the left arm in forward kinematics, press the 'Snap IK to FK' button in the rig UI, and then the inverse kinematics controls will position themselves to match the position of the forward kinematics control
If 'Auto Switch Kinematics on Snap' is enabled, the IK/FK toggle will automatically switch to whatever kinematics context was snapped to.
If 'Auto Key Snaps' is enabled, a keyframe on the current frame and one on the previous frame will be added that instantly perform the transition in the animation.