PixCap Docs
IK Setup
IK (Inverse Kinematics) is a powerful alternative to FK (forward kinematics) for animating complex chains. See more info on IK here, including how to blend between FK and IK. IK is well-suited for moving limbs to a position in 3D space, such as planting a foot onto the ground and animating a walk cycle.
Similar to retargeting, IK setup can be found by click on any bone on the character or scene tree. Then in the inspector, click the “IK Setup Mode” button.
Similar to retargeting, IK setup automatically best guesses each relevant limb bone to match the IK slot. This can be changed by clicking on the target icon
slot, which will open a dropdown of all the bones to choose from. Pick the bone that is used as the end effector bone.
Press “Create” to create the relevant IK type, then “Save”. To quit IK setup mode, press “Cancel”.

IK Types

There are 2 IK Types for Feet IK
  • Normal IK (three bone chain, also the default type for Hand IK) and Reverse Foot (four bone chain).
  • A typical Normal IK setup for the left leg is as follows: Left Thigh, Left Knee, Left Foot (end effector). The Reverse Foot setup would be as follows: Left Thigh, Left Knee, Left Foot, Left Toe (end effector).

IK Handles

IK controls are represented as a white torus ring handle. Left click on the IK handles to adjust settings and test the animation on the impacted bones. Right click to force IK to stick to its position irrespective of the root node. (IK pinning = ON)

General IK Settings

  • FK/IK Blend: The amount to blend the underlying character mesh between FK vs IK. If value is 1, the character mesh will follow the IK chain. If value is 0, the character mesh will follow the FK chain.
  • Pole Angle: Angles in degrees representing the direction that the middle joint in the IK chain should point to. E.g. the rotation of knee

IK bone visibility

For a cleaner look, the FK bones will be hidden when the value or IK blend is at 1 and vice versa.

Reverse Foot Settings

The Reverse Foot IK consists of all settings from Normal IK, with one additional Foot Rotation property.
  • Foot Rotation. Defines how much the foot rotates along the IK handle in the X (forward), Y (twist) and Z (bank) angles. Hold Shift + Drag on the rotation gizmo to trigger foot rotation.
The Foot Rotation property offers more control over how the foot rolls, twists or moves forward relative to the IK handle. In this example, the Foot Rotation X is set at 40 degrees, indicating a forward angle. This creates a “tip-toe” effect without needing to adjust the rotation of the actual IK handle.

Adjusting and Setting Up Reverse Foot

For best results, Reverse Foot requires the IK handle to be placed parallel to the ground (XZ axis, Y value = 0) during setup. This can be adjusted by clicking on the Reverse Foot handle and then clicking the “Adjust Foot” sub-tab in IK mode.
When “Adjust Foot” is in effect, moving the IK handle will not animate the IK bone chain. Instead, this mode is used to adjust the position and rotation of the IK handle with respect to the foot (or toe) node.
GOOD The position and rotation fit the foot to ground placement, and the size is appropriate (defined by the 4 adjustable pivots: front, back, left, right).
NOT GOOD Both the position and rotation are not well placed relative to the foot.

Finalizing IK Setup

Once you are happy with the overall IK setup, press “Apply”. This will redirect you back to Animation mode, with the new IK handles created for the character in the scene.