The IK ‘even eleven’ spline spine rig is a rig that uses an IK Spline for the rig to be controlled. Even eleven refers to the fact that there are eleven even joints in this spine. Eleven joints are created and evenly spaced to create the spine. These joints are named spine_Joint1 through to spine_Joint11 with the first joint starting at the bottom of the spine and 11 being at the top.
Next is to connect an IK Spline from spine 1 to spine 11. Select the IK Spline Handle tool (with ‘Auto Parent Curve’ off) and select from spine_Joint1 to spine_Joint11. Rename this IK Solver’s curve ‘splineCurve’.
Open the ‘Joint Tool’ Settings and make sure that the orient joint is set to world. Make a single joint one unit back from spine_Joint1. Name this joint Spline_joint_start. Repeat this process at spine_Joint11 and name it spline_joint_end. Point snap these joints to their spine joints (ie. spline_joint_start is point snapped to spine_Joint1 and spline_joint_end is point snapped to spine_Joint11).
Select the start joint, the end joint and the curve. Open the interactive skin bind options and reset the settings. Change ‘bind to’ to ‘selected joints’. Hit apply.
Now create a chest control. Place this so its pivot is snapped to the spline_joint_end. This is going to control the movement of the spine and it’s advanced twist controls. Select the chest control (master) and then the spline_joint_end (slave) and parent constrain. This allows the spine to move back and forth.
Next, the advanced twist needs to be set up. The advanced twist allows the spine to recreate a believable and realistic twist that can be easily controlled from the chest control. Open the advanced twist controls in the spline handle and tick on Enable Twist Controls.
- World Up Type = Object otation Up (Start/End)
- Up Axis = Negative Z
- Up Vector = 0, 0, -1
- Up Vector 2 = 0, 0, -1
- World Up Object = The is no World Up Object
- World Up Object 2 = chest_Control
Once this has been complete, the chest control will be able to perform the advanced twist for the spine when it is rotated in the y axis. The rig is now complete.