create_fk_ik_chain_switch

Already made something like this years ago for my mock auto rigging. Making this one again for a manual rigging tasks on custom game model

import maya.cmds as cmds
import pymel.core as pm

def create_joint_chain():
    # Create the main joint chain
    joints = []
    joint_names = ["shoulder_jnt", "elbow_jnt", "hand_jnt"]
    positions = [(0, 10, 0), (1, 5, 0), (0, 0, 0)]

    for name, pos in zip(joint_names, positions):
        jnt = pm.joint(name=name, position=pos)
        joints.append(jnt)

    pm.select(clear=True)
    return joints

def duplicate_joint_chain(joint_chain, prefix):
    
    new_joint_chain = pm.duplicate(joint_chain)

    for joint in new_joint_chain:
        new_name = prefix + joint.nodeName().split("1")[0]
        pm.rename(joint, new_name)

    return new_joint_chain

def setup_ik_fk_switch(main_chain, fk_chain, ik_chain):
    # Create IK Handle for the IK chain
    ik_handle, effector = pm.ikHandle(startJoint=ik_chain[0], endEffector=ik_chain[-1], solver="ikRPsolver", name="arm_ikHandle")
    effector.rename(ik_chain[-1] + "_eff")
    
    # Create a control for the IK handle
    ik_control = pm.circle(name="ik_ctrl", normal=[0, 1, 0])[0]
    pm.delete(pm.parentConstraint(ik_chain[-1], ik_control))
    pm.parent(ik_handle, ik_control)
    
    # Create FK controls
    fk_controls = []
    for fk_jnt in fk_chain:
        fk_ctrl = pm.circle(name=fk_jnt.name().replace("_jnt", "_ctrl"), normal=[0, 1, 0])[0]
        pm.delete(pm.parentConstraint(fk_jnt, fk_ctrl))
        pm.parentConstraint(fk_ctrl, fk_jnt, maintainOffset=True)
        fk_controls.append(fk_ctrl)
    
    pm.parent(fk_controls[2], fk_controls[1])
    pm.parent(fk_controls[1], fk_controls[0])

    # Create IK/FK switch attribute
    switch_ctrl = pm.circle(name="ik_fk_switch_ctrl", normal=[0, 1, 0])[0]
    switch_ctrl.addAttr("IK_FK_Switch", attributeType="float", minValue=0, maxValue=1, defaultValue=0, keyable=True)
    
    # Constrain the main joints to the FK and IK joints
    for main_jnt, fk_jnt, ik_jnt in zip(main_chain, fk_chain, ik_chain):
        orient_constr = pm.orientConstraint(fk_jnt, ik_jnt, main_jnt)
        pm.connectAttr(switch_ctrl.IK_FK_Switch, orient_constr.attr(ik_jnt.nodeName() + "W1"))
        rev_node = pm.createNode("reverse", name=main_jnt.nodeName() + "_ikFkRev")
        pm.connectAttr(switch_ctrl.IK_FK_Switch, rev_node + ".inputX")
        pm.connectAttr(rev_node + ".outputX", orient_constr.attr(fk_jnt.nodeName() + "W0"))
    


    
    # # Organize in groups
    # pm.group(main_chain[0], name="main_joints_grp")
    # pm.group(fk_controls, name="fk_controls_grp")
    # pm.group(ik_control, ik_chain[0], name="ik_controls_grp")
    # pm.group(switch_ctrl, name="ik_fk_switch_grp")

if __name__ == "__main__":
    main_joints = create_joint_chain()
    fk_joints = duplicate_joint_chain(main_joints, "FK_")
    #print (fk_joints[0].name())
    ik_joints = duplicate_joint_chain(main_joints, "IK_")
    #print (ik_joints[0].name())
    setup_ik_fk_switch(main_joints, fk_joints, ik_joints)