CCDIK Rig Parenting Issues

When parenting a CCDIK (Cyclic Coordinate Descent Inverse Kinematics) rig to a vehicle, transform issues are common. The problem you're experiencing with the rig failing and mesh disappearing is likely related to how the IK system handles coordinate space transformations when parented.

Here are some approaches to solve this issue:

Use a Buffer Object

Create an empty game object as an intermediary between your vehicle and the character rig:

CSHARPCopied
// Create a buffer object in code
GameObject bufferObject = new GameObject("RigBuffer");
bufferObject.transform.parent = vehicleTransform;
characterRig.transform.parent = bufferObject.transform;

Maintain World Position

When parenting, preserve the world position and rotation:

CSHARPCopied
// Store original world position/rotation
Vector3 worldPos = characterRig.transform.position;
Quaternion worldRot = characterRig.transform.rotation;

// Parent to vehicle
characterRig.transform.parent = vehicleTransform;

// Restore world position/rotation
characterRig.transform.position = worldPos;
characterRig.transform.rotation = worldRot;

Use Local Space Offsets

Calculate and maintain local space offsets:

CSHARPCopied
// Calculate local offset before parenting
Vector3 localOffset = vehicleTransform.InverseTransformPoint(characterRig.transform.position);
Quaternion localRotOffset = Quaternion.Inverse(vehicleTransform.rotation) * characterRig.transform.rotation;

// Apply offset after parenting
characterRig.transform.parent = vehicleTransform;
characterRig.transform.localPosition = localOffset;
characterRig.transform.localRotation = localRotOffset;

Disable and Re-enable IK

Sometimes temporarily disabling the IK system during the parenting operation helps:

CSHARPCopied
// Disable IK components
CCDIKSolver ikSolver = characterRig.GetComponent<CCDIKSolver>();
bool wasEnabled = ikSolver.enabled;
ikSolver.enabled = false;

// Perform parenting
characterRig.transform.parent = vehicleTransform;

// Re-enable IK
ikSolver.enabled = wasEnabled;

Try these approaches to see which one works best for your specific setup. The key is managing the coordinate space transformations properly during the parenting operation.