It works by duplicating the three joints and building the switch through the node system. The script can only work on a three joint chain that has the three joints parented to each other. If there is a joint inbetween any of the main joints (twist joints in arms) the script won't work. But if there are other joints parented to the main joints, but not inbetween the three selected joints, the script will still work. The script will also create the ikHandle on the Ik control joints.
Directions: just copy the script into a shelf button, shift select the three joints you want the controller joints applied to from base to end and the controller you want the switch applied to last, and run the script.
The script builds the control joints and the rigger should go back and rename the joints to whatever they what them to be. You will still need to set up the visibility of the contollers but the control joints are already setup.
The order of the selection should be (Base joint, Mid joint, End joint, and Ik/Fk Controller).
To set up the visiblility of the controllers just go into the node editor and show the Ik/Fk controller. There is a reverse node that is applied to the switch. The visibility of the Fk controllers go to the Ik/FkSwitch and Ik controllers connect to the reverse of the control switch.
I made this script to make rigging for video games faster, though it can be used with any rig.
Update: The Script how builds the Ik and Fk controles in the model. The only conrole it doesnt build is the Ik Elbow CTL. Using the script is exactly the same as before
Set Up: The script now goes into your Maya Scripts Folder and you place the RunIkFkSwitchBuilder to run the main Script.
The RunIkFkSwitch Builder script consists of:
Just paist these two lines into a python button in your shelf and it will run the builder.
To adjust the controles to fit your model's better just move the Controle Vertexes.